Elektor Voltage Current Calibrator Project - Page 1
Forum section: electronics / testgear

author: Martin72
author_rank: Super Contributor
timestamp: July 15, 2023, 09:52:26 pm
content: Hi,Quote from: KungFuJoshHere we go...To keep the otherthreadcleaner.Stumbled over this a few days ago:https://www.elektormagazine.de/labs/voltage-current-calibrator-0-to-10v-and-0-to-40ma-0001Looks really neat..Already ordered the PCB, then look into the BOMs....Boy...not a cheapo.JLCPCB also offer 3d printing even in metal (interesting for the frontpanel and the heater housing)and so damn cheap, that the one, two expensive components (one chip, then the display) won´t hurt so much.10ppm accuracy sounds not too bad, for the calibration of the calibrator a voltmeter with at least 6.5 digits is recommended.When I decide to build this I would let it calibrate, not by myself.

author: Martin72
author_rank: Super Contributor
timestamp: July 15, 2023, 10:06:10 pm
content: Here a (temporary, will delete it in 24h) link to the docs:

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 15, 2023, 10:17:40 pm
content: Ooh, I'm happy to see the KiCad files. That means I can run DRC and mess around a little before ordering.

author: Martin72
author_rank: Super Contributor
timestamp: July 15, 2023, 10:24:12 pm
content: Nice...Maybe I change to KiCad too, my premium license for Eagle is void.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 15, 2023, 10:29:12 pm
content: I love KiCad. It works great, and it's free. 😉I've also used FreeCAD to make 3D objects for my PCB projects. Like the largest inductor on my PCB in the other thread.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 15, 2023, 11:45:27 pm
content: I'm cleaning up the silkscreens. C12 and C14 are labeled backwards. This is somewhat obvious if you pay attention to the fact that C14 is polarized, and the silkscreen next to C12 is polarized. They're parallel to each other, so it doesn't really matter, but it's pretty sloppy on their part.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 15, 2023, 11:54:23 pm
content: Much better. Now it's accurate and easier to read. 👍

author: Martin72
author_rank: Super Contributor
timestamp: July 15, 2023, 11:54:51 pm
content: For whatever reason JLPCB has problems with the correct display of the placement imprint anyway.So the designations like to "disappear" into the component print, when I think of it, I always position the designations with some distance to it.This time I have not thought about it, because not my board..

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 16, 2023, 12:03:20 am
content: I've been using JLC for years, and I haven't really had any trouble with that. This design had the silkscreens literally on top of pads and other stuff that would make it useless anyway. The heater board was worse, but I fixed that too.Right now, I'm cleaning of the tracks. It's a real mess. It had pretty close to 100 errors in DRC. Nothing terrible yet, mostly just really sloppy traces going nowhere for no reason in random spots.Edit: What thickness did you order for these PCBs?

author: Martin72
author_rank: Super Contributor
timestamp: July 16, 2023, 01:28:42 am
content: Always the standard, 1.6mm .It´s more than enough as you don´t have any heavy weight parts on it.For a e.g. transformer board we use 2.4mm, anything less than this let it all hang down.

author: Martin72
author_rank: Super Contributor
timestamp: July 16, 2023, 11:21:33 pm
content: Interesting, the 3d printing parts were rejected from JLCPCB, reason:Too thin, they recommend at least 1.5mm thickness.No problem, I must calculate the whole thing, because:https://www.ianjohnston.com/index.php/onlineshop/handheld-precision-digital-voltage-source-2-mini-detailCon: No current source, Pros: More precise, (inhouse-) calibrated on a 8.5 digit meter...And it´s complete assembled, tested, for 325 pounds.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 17, 2023, 12:01:48 am
content: Quote from: Martin72 on July 16, 2023, 11:21:33 pmKnowing you, it's going out for calibration either way. 😉The DIY version looks like a fun project.If I make it, I'll use my laser to cut a clear panel for it.I can also mark the outside of the enclosure for the cuts. I eventually want a fiber laser, so if I get that first, that can make the enclosure cuts too.Edit: It's a touch screen. I'll probably just put a screen protector on it.I wouldn't be surprised if you went for both projects anyway. Look at it this way, you can get the PDVS2mini now, and then wait until next year when the parts are cheaper to build the project reference. That practically pays for the PDVS2....and then buy another reference you find somewhere else. 🤣

author: Martin72
author_rank: Super Contributor
timestamp: July 17, 2023, 12:10:45 am
content: At work, I am the testfield manager.At home, I cultivate my hobby, which also happens to have something to do with electronics.Then there's the fact that I'm curious and open to everything that goes in that direction.And I like to pay apprenticeship money, because as ALF once said:There is nothing good, unless you do it.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 17, 2023, 01:49:36 am
content: ALF also said: “Where do you keep your casserole dishes? The cat wont fit in the toaster.”

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 17, 2023, 05:54:06 pm
content: I made a project on Mouser with all the main board parts. It's $366 USD including the $85 version of that out of stock chip.I attached a Mouser BOM, but the parts need to be verified. The original supplied BOM has accuracy issues with the reference numbers.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 17, 2023, 06:50:56 pm
content: Here's the heater's BOM. Also needs verification. The original had quantity issues.

author: Martin72
author_rank: Super Contributor
timestamp: July 17, 2023, 07:05:36 pm
content: Hi,Sure that these are the complete BOMs ?

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 17, 2023, 07:09:58 pm
content: Pretty sure. 😉As I said, they need verification. I did substitute some parts that were no longer available.

author: Martin72
author_rank: Super Contributor
timestamp: July 17, 2023, 07:33:27 pm
content: Then I´ve done something wrong..I count 13 lines on the first excel list(I don´t have Excel on my notebook, so I went to my PC and printed it out as a pdf, maybe a failure occured then)

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 17, 2023, 07:48:15 pm
content: I don't think it was you. This forum (SMF) is buggy sometimes, and it screwed up the files. The main BOM has 44 lines, and I downloaded it, and it showed the heater BOM instead.Here's both again. Hopefully it works this time. They both need verification for quantity and part accuracy. As mentioned previously, reference numbers were not all correct in the original BOMs.

author: tautech
author_rank: Super Contributor
timestamp: July 17, 2023, 08:25:12 pm
content: Quote from: KungFuJosh on July 17, 2023, 07:48:15 pmYup.Neveruse the first Choose File option,never!Instead selectmore attachmentsand link yours in there however then you are restricted to 9/post but it sidesteps the forum problems.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 17, 2023, 11:02:08 pm
content: Quote from: tautech on July 17, 2023, 08:25:12 pmI usually drag and drop, and it usually works. AFAIK, this was the first time it actually confused the files like that.

author: Martin72
author_rank: Super Contributor
timestamp: July 17, 2023, 11:12:03 pm
content: I had/have the same with pics...When I´ll upload more than one and then in an order, I always ignore the first upload and start with the second.The DAC in this project..There´s a "combo" with it and the LTZ1000 reference, together you "gain" a reference with 1ppm accuracy..Nice.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 17, 2023, 11:22:50 pm
content: Do you think this project is worth the $400+ USD price tag?

author: Martin72
author_rank: Super Contributor
timestamp: July 17, 2023, 11:51:51 pm
content: Honestly?When you stretch it for month so it doesn´t hurt you directly in case of the costs, why not.But if you take the money instantly in your hands I would go for the complete assembled, tested and burned-in reference I´ve linked a few posts before.It do not have the current source, but it is "calibrated" with a 8.5 digit meter.Me I would go the way of "stretching" this project.Like I said before, theoretically it could be "tuned" to a 1ppm reference..awesome.But most of what I expect from it is to learn how things work in detail and then possibly improve them.That's actually how I've always done it in the past.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 18, 2023, 02:08:41 am
content: Well, I ordered the PCBs. 🤦

author: Martin72
author_rank: Super Contributor
timestamp: July 22, 2023, 02:45:01 pm
content: Well, mine arrived today..

author: Martin72
author_rank: Super Contributor
timestamp: July 22, 2023, 08:52:39 pm
content: Quote from: KungFuJosh on July 17, 2023, 07:48:15 pmTested it a few minutes ago by importing the main list into my mouser account.Batteypack won´t be avaible for me(my region), display won´t be avaible (only for OEM)...This was the first test, tomorrow I´ll check your list completely.Display I must get from somewhere else, the housing I like to have it in silver.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 22, 2023, 09:25:57 pm
content: Quote from: Martin72 on July 22, 2023, 08:52:39 pmHere's the LCD direct from the manufacturer:https://4dsystems.com.au/products/ulcd-35dt/For the regular enclosure, just remove the BK color from the model name:https://www.mouser.com/ProductDetail/546-1455J1202The battery is uncertain based on size anyway. You might be able to get the original battery from the original BOM (wasn't available to me here in the US).

author: Martin72
author_rank: Super Contributor
timestamp: July 22, 2023, 09:36:47 pm
content: Damn....I think I´ll order the parts next week....

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 22, 2023, 09:39:01 pm
content: Quote from: Martin72 on July 22, 2023, 09:36:47 pmMe too. I had to stop myself from ordering them a couple times already lol. But I think I'll have my PCBs on Monday. We'll see how patient I am.

author: Martin72
author_rank: Super Contributor
timestamp: July 22, 2023, 09:42:49 pm
content: QuoteI felt the same way.First wait, but then the boards were there and now...crap.

author: Martin72
author_rank: Super Contributor
timestamp: July 23, 2023, 05:01:15 pm
content: Made the order by mouser.Without housing (can get it cheaper), display, battery, 4mm jacks, several ICs (not in stock) and one resistor (not in stock).All in 156€...Hint : The AD5791 will be avaible soon (August) by DigikeyEdit:Missing parts:MCP1501T-33E/CHY (11/23 in stock (Digikey) )MAX6350CSA+ (CSA: 1ppm tolerance) (09/23 in stock (Digikey)AD8676 (11/23 in stock (Digikey) )AD5791 (08/23 in stock (Digikey))Vishay 100Ohm 0.02% 0.2ppm (in stock by digikey)

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 23, 2023, 06:31:49 pm
content: Oh yeah, I forgot to add that $17 resistor. I was planning to find a less expensive but same spec resistor, but I don't think that's gonna happen. 🙄 Oh well. I added Y1625100R000Q9R to the project.The rest is on the list, but backordered. I have a separate project for the backordered stuff to keep ordering simple. 😉

author: Martin72
author_rank: Super Contributor
timestamp: July 23, 2023, 11:07:29 pm
content: So, display, housing and banana jacks ordered, that´s enough for now and this month.Forget to order the heater-pcb...Will do it plus ordering the 3D print parts.Then I´ll have a pause because of the missing semiconductors.Good..

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 25, 2023, 12:57:20 am
content: Well, mine arrived today...

author: Martin72
author_rank: Super Contributor
timestamp: July 25, 2023, 01:22:31 am
content: Ah, in fancy brown style..

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 25, 2023, 03:48:04 am
content: It's actually black, that's the lighting playing tricks. Now that I've got it, I paid more attention, and I'm not happy about the micro USB jack. I want to do it with USB-C. I know it's just for charging, but I hate paying attention to micro USB cables.I'll probably see if I can bodge a charging only USB-C port to it. I think I have enough PCBs to experiment. 🤷Edit: Who am I kidding, I'll just order a new board version with a USB-C charging port for $10 when I order other stuff. 😉

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 25, 2023, 12:45:21 pm
content: Quote from: Martin72 on July 23, 2023, 11:07:29 pmIf you don't rush, I can send you the gerbers when I'm done changing it to USB-C power jack, and seeing if there's anything else that needs attention. There were a couple warnings when updating the PCB from schematic.I'm glad I saw that line about 3D printed parts, I totally missed that. Oops.

author: Martin72
author_rank: Super Contributor
timestamp: July 25, 2023, 03:19:43 pm
content: Hi,The housing has already arrived today, looks well made, nice.BUT:The board does not fit, it is a tad too wide, maybe 0.8mm ...This is just to warn you (and others) about reordering the boards.Sure, you could go ahead and grind one side of the board, but I think that's a bit uncool...

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 25, 2023, 04:34:12 pm
content: That's a minor issue. There are some small variances in the posted dimensions between the different colors of those enclosures. I haven't looked closer than that.I won't change the PCB dimensions right now because the alignment to the screen is more important than the chassis dimensions, and you either need to trim both sides the full variance amount, or figure out where the dimensional change needs to be made to stay consistent with the LCD mounting.Well, maybe trimming 1mm off both ends of the board is okay. I'll look at it, I'm working on it anyway.BTW- there are BOM discrepancies between what KiCad exported and what was supplied with the kit. I'm making a PCBA BOM now to see what small stuff I can get out of the way, and if it's worth it or not.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 25, 2023, 05:19:43 pm
content: In the BOM, R16 is 100Ω, but on the PCB R16 is 1kΩ. I read the article page, and the original BOM is wrong, the schematic is correct. Also, the schematic was lazy. They wrote 1k but didn't include that it needs to also be 2ppm/C or better.

author: Martin72
author_rank: Super Contributor
timestamp: July 25, 2023, 05:34:23 pm
content: So R16-R20 must have it..OK, thanks for checking this

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 25, 2023, 05:44:39 pm
content: Quote from: Martin72 on July 25, 2023, 05:34:23 pmYup. When a set of resistors needs to have a specific temp co, then all of the resistors in that group need to match. Or so I'm told. 😉

author: Martin72
author_rank: Super Contributor
timestamp: July 25, 2023, 06:54:03 pm
content: They told you that right.OK, then I have to get a 1k resistor of the same kind.https://www.mouser.de/ProductDetail/TE-Connectivity-Holsworthy/RU73X2A1K0LTDF?qs=CXI0wBT1M2iYnqPwpNKfVg%3D%3D

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 25, 2023, 07:55:37 pm
content: Quote from: Martin72 on July 25, 2023, 06:54:03 pmlol, no, a friend of mine. I'm designing another circuit, and we're using an LTC6090, and he made sure to point that out about the tempco. 😉I updated and verified my BOM vs. the schematic, and yes, that's the correct resistor. Nothing should be missing, but there might be something extra. 🤷

author: Martin72
author_rank: Super Contributor
timestamp: July 25, 2023, 08:28:34 pm
content: Btw, here the evaluation board with LTZ1000 reference:https://www.digikey.de/de/products/detail/analog-devices-inc/EV-LTZ1000-REFZ/8598410And here the very interesting User guide :https://www.analog.com/media/en/technical-documentation/user-guides/eval-ad5791sdz-ug-1152.pdfIt is already quite similar.But maybe you can hardly do it any other way....

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 25, 2023, 09:20:06 pm
content: I updated my Mouser project again. AD8676 was the wrong size. All of them are backordered, so you probably didn't order it yet anyway. 😉

author: Martin72
author_rank: Super Contributor
timestamp: July 25, 2023, 09:24:24 pm
content: QuoteI have already fallen for it in 2 other projects, the components arrive - Mehhh...wrong design, does not fit by any stretch of the imagination, reorder again...Annoying.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 25, 2023, 10:46:10 pm
content: Quote from: Martin72 on July 25, 2023, 09:24:24 pmI know the feeling. I did warn you about parts needing to be verified though. I have JLC part numbers for almost everything now too. Unfortunately, most of it is only on their extended parts list. I might see about preordering stuff so they can assemble what's available.

author: Martin72
author_rank: Super Contributor
timestamp: July 25, 2023, 10:52:12 pm
content: My Mouser order should arrive on thursday, friday at work (FedEx is horrible when you´re not at home, so I leave the company adress instead).Funny thing: Although there´s a Mouser Adress in germany, the ordered goods are coming from the States.Display should arrive tomorrow from TME.

author: Martin72
author_rank: Super Contributor
timestamp: July 25, 2023, 11:33:23 pm
content: I was also wondering why the display costs so much money...3.5" and touch is not a big burner now.After I had downloaded the data sheet, however, it was more comprehensible.Display, input interface and controller for the rest...Well, then it makes sense to me.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 26, 2023, 01:33:44 am
content: Basically we're stuck with the screen he designed this with. There are similar screens with similar feature sets for less cash.BTW- found another error on the BOM. G6K-2 had a Y in it, which changes the spacing. I corrected it in the Mouser project. It's probably good now. 🤦

author: Martin72
author_rank: Super Contributor
timestamp: July 26, 2023, 02:02:01 pm
content: Now the pcb fits into the housing..But some parts are coming very close to the housing, must take care when soldering the parts.And the super-duper-expensive-display has arrived.OK, the building quality is superb, no question.First I thought "and how to connect this ?!" - But there´s an adaptor in the package...Puhh.Edit: I gues for programming the display.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 26, 2023, 03:04:59 pm
content: It looks like you bought the "gen 4" version of the screen.You need this one:https://4dsystems.com.au/products/ulcd-35dt/But it looks like you got this one:https://4dsystems.com.au/products/gen4-ulcd-35dt/I'm going to reorder the PCB with USB-C on it. I removed .5mm from the top of the PCB, and 1mm from the bottom of the PCB.

author: Martin72
author_rank: Super Contributor
timestamp: July 26, 2023, 03:11:17 pm
content: Brilliant, just brillant....I hate resending

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 26, 2023, 03:13:30 pm
content: Quote from: Martin72 on July 26, 2023, 03:11:17 pmDid they send you the wrong one? Either way, I'd be surprised if they weren't nice about it.

author: Martin72
author_rank: Super Contributor
timestamp: July 26, 2023, 03:19:40 pm
content: I did a mistake and searched for it by using google.They also having the right one(30 bucks more)..fu**

author: Martin72
author_rank: Super Contributor
timestamp: July 26, 2023, 03:34:07 pm
content: https://www.tme.eu/de/details/ulcd-35dt/intelligente-displays/4d-systems/The right one, on stock...https://www.tme.eu/de/details/gen4-ulcd-35d/intelligente-displays/4d-systems/Mine...OK, return to sender.Edit: Pic from his project

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 26, 2023, 04:46:53 pm
content: Quote from: Martin72 on July 26, 2023, 03:19:40 pmAnd you thought it was expensive before. 😉

author: Martin72
author_rank: Super Contributor
timestamp: July 26, 2023, 07:12:54 pm
content: Oh yes...At least the program seems to work.Software:Workshop4 IDEAnd we need a programming cable..

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 26, 2023, 07:59:50 pm
content: Interesting. What's the interface for programming? Direct to chip?

author: Martin72
author_rank: Super Contributor
timestamp: July 26, 2023, 08:07:45 pm
content: Ithink, it´s this one here:https://4dsystems.com.au/products/4d-upa/Or this:https://de.rs-online.com/web/p/entwicklungstool-zubehor/8417875

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 26, 2023, 10:01:29 pm
content: The first one you listed is for gen4 panels, which we don't want.The second one might work (but it probably needs a chip; no chip, probably no work). Looking closely at the image of the (correct) panel, it shows RES GND RX TX +5V. That sounds to me like a serial to USB 2.0 converter module is what's used.Anyway, this is probably the correct one from them (and just looks like a USB adapter):https://4dsystems.com.au/products/uusb-pa5-ii/That has an FTDI FT232 USB chip on it, so my guess is, if you have another serial USB or Serial over Bluetooth module, you could probably get that to work.I know this is a crazy question, but did you RTFM for the screen yet? Maybe there's some insight in there.Did the guy who made the project use the programmer, or was the whole thing done through the microSD card?

author: Martin72
author_rank: Super Contributor
timestamp: July 26, 2023, 10:18:01 pm
content: Hi,QuoteTheir programming cable have a serial-usb converter in the connector housing.QuoteAs ever, I flew over the pages...QuoteQuoteIf it´s possible I want to avoid this and program the controller directly.When I´ll get the right display I´ll take more care to read the manual...

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 26, 2023, 10:28:33 pm
content: Quote from: Martin72 on July 26, 2023, 10:18:01 pmI would be surprised if it's possible. Whether programming directly is necessary or not, I don't know. I didn't read anything yet. 😉However, I know there are images and sound files involved, so storage is necessary. I don't know how much storage the LCD has without the microSD.

author: Martin72
author_rank: Super Contributor
timestamp: July 26, 2023, 10:36:22 pm
content: That´s a good point.https://www.elektormagazine.de/labs/voltage-current-calibrator-0-to-10v-and-0-to-40ma-0001#Interesting points on the section improvements..

author: Martin72
author_rank: Super Contributor
timestamp: July 27, 2023, 05:46:42 pm
content: Hi,QuoteIn the datasheet it is written that it is indeed exactly for this, you can also store logger data on it:QuoteWhat is also interesting, so for a programming layman like me:Quote

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 27, 2023, 06:58:27 pm
content: I think it will be pretty cool if we can easily customize the interface. However, he already made graphics for it, so it seems like the programming was done already, and it just needs to be copied over? I guess we'll find out eventually.I'd still bet a serial to USB cable or adapter is all that's needed for the programming cable. I have real programmers too, but I don't know if they'd work with that or not.

author: Martin72
author_rank: Super Contributor
timestamp: July 27, 2023, 07:35:17 pm
content: QuoteIt is:https://docs.rs-online.com/d92d/0900766b815118a7.pdfQuoteAll we need is already there.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 27, 2023, 08:08:26 pm
content: That's what I thought. So it seems the extent of "programming" is just copying his files over. I may have a look at them with that utility and see what kind of customization can be done.

author: Martin72
author_rank: Super Contributor
timestamp: July 27, 2023, 08:17:55 pm
content: I´ll check this in the next week I guess - Ordered the "right" display today and somewhere I must have a USB to serial adaptor lying around.

author: Martin72
author_rank: Super Contributor
timestamp: July 28, 2023, 03:19:50 pm
content: Stop - Hammertime ! Ehhh...Mousertime.

author: Martin72
author_rank: Super Contributor
timestamp: July 28, 2023, 08:37:16 pm
content: Comparing the BOM (original) with the schematic....R21(10R) is missed in the BOM but in the schematic avaible and must be there because it´s the output resistor.Then it´s getting "wilder"...2µ2 tantalum are only mentioned as C9,C10 in the BOM but also avaible as C30,C33,C36 in the schematic..According to the datsheet of the MAX6350 (U9) C30 and C36 are right with 2µ2 (and wrong in the BOM), for C33 (100nF in the BOM) the datasheet recommending 1µF, in the schematic it´s 2µ2.And another thing:C28 is 10µF in the schematic (and right), but 100nF in the BOM....I´ll continue checking BOM vs schematic.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 28, 2023, 10:22:11 pm
content: Your BOM must be outdated. I have a new BOM I verified with the schematic. Try the attached BOM instead. I don't remember if I updated my project yet. I got sidetracked with...work. 😉

author: Martin72
author_rank: Super Contributor
timestamp: July 28, 2023, 10:26:49 pm
content: Argh, excel again...So you also found out that D4 does not exist?I looked at the MAX6350 datasheet again, 1µF for the NR input is recommended, but if it's more it won't have any effect, so the 2µ2 can stay that way.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 28, 2023, 10:43:42 pm
content: I exported a BOM from Kicad and verified that way. Much easier than the original goofy BOM that had some bad info in it.

author: Martin72
author_rank: Super Contributor
timestamp: July 29, 2023, 03:32:10 pm
content: The right display arrived...But it seems not so easy just to take a common usb-serial adaptor and then everything´s fine.I got a notebook with a native com port, tried this first...nothing.Then took the adaptor, tried again...nothing.The display won´t start when the RX/TX pins are connected to the com port or to the adaptor.Maybe the RESET pin plays a role too, must examine it further.Or buy the original adaptor.(adaptor pic made before changing the connection)

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 29, 2023, 04:01:31 pm
content: Your pictures don't make the wiring clear. Do this:If you're powering from an external PSU, connect power and ground to the screen, and make sure ground also goes to the serial port adapter.Connect Rx/Tx backwards at the serial port adapter and see if that works.

author: Martin72
author_rank: Super Contributor
timestamp: July 29, 2023, 04:07:32 pm
content: Thank you josh, but this was already made.Will continue testing.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 29, 2023, 04:08:46 pm
content: Quote from: Martin72 on July 29, 2023, 04:07:32 pmDo you mean you got it working?

author: Martin72
author_rank: Super Contributor
timestamp: July 29, 2023, 04:16:18 pm
content: Sorry, the connections were meant...

author: Martin72
author_rank: Super Contributor
timestamp: July 29, 2023, 08:57:56 pm
content: I have now rather stopped experimenting, not that I still break the 120 euro display.USB to serial TTL converters are available like sand on the beach and super cheap.And many look almost exactly like the "original" from 4D.I ordered one from Amazon and it will arrive on Monday.It's so cheap that it doesn't hurt if it doesn't work.Because the adapter from 4D has something that all the others don't have, the reset output.And it is also triggered, for a hundred milliseconds.If it turns out on Monday that the ordered adapter does not work with it, well then I have to buy the original.I have made again parts list control, what do I have here, what am I still missing....I soldered nothing yet, I will take the board with me to work and let the coils L1/L2 and the USB port soldering there because no way to do it here.Oh, and the Heater board is now also ordered.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 29, 2023, 11:25:26 pm
content: I usually use the FT232 USB chip stuff, I'm guessing that will work when I eventually get this. I'm also curious if my PicKits would work or not.If you know which pin to connect the RES to, then it may work with what you have. I think RTS (pin 7) is the correct pin.

author: Martin72
author_rank: Super Contributor
timestamp: July 29, 2023, 11:37:40 pm
content: If I remember it right it is DTS, will confirm this yes/no later.What I haven't quite figured out yet is why the display turns off/not even starts up once the RX/TX lines are/will be connected.And I know about potentials, believe me....

author: Andreas
author_rank: Super Contributor
timestamp: July 30, 2023, 05:43:31 am
content: Quote from: Martin72 on July 28, 2023, 10:26:49 pmThe NR pin is rather high-ohmic and has direct influence on the output voltage stability.I would never use a tantalum (with high leakage current) here.I would use a film capacitor. (or leave it unpopulated since it only helps with wideband noise).with best regardsAndreas

author: Kleinstein
author_rank: Super Contributor
timestamp: July 30, 2023, 06:05:19 am
content: Most of the cheap USB to uart adapter are just that: UART output (3.3 or 5 V level), similar to what a µC provides or wants. So there are no drivers to get the +-10 V levels for RS232 like a generic PC serial part.+1 with using a film capacitor for the NR pin of the reference. A tantalum or Al electrolytic is more a no go. A ceramic X7R or similar may work, but is not ideal. Even if only for the higher frequency noise, it helps to have at least some filtering. 1 µF film caps (MKS) are still afordable and not excessively large.

author: djsb
author_rank: Super Contributor
timestamp: July 30, 2023, 07:33:01 am
content: Where are the UPDATED Kicad files for this project? And where is the link to the ORIGINAL Elektor article? Thanks.David.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 30, 2023, 04:18:44 pm
content: MKS caps are only radial, it needs to be SMD for this project.25MU105MA2321625V 1µF 1206 SMD20%would probably be a good 1µF film substitute to fit the same footprint. Not cheap, but certainly not that expensive compared to other parts in this project.Why wouldn't an X7R cap be good for that?C1206C105J3RACAUTO25V 1uF X7R 12065%is only 40 cents instead of $4.00.

author: Martin72
author_rank: Super Contributor
timestamp: July 30, 2023, 04:49:51 pm
content: Hi Josh,MKS02 wouldn´t be a problem, I just test it out...

author: Martin72
author_rank: Super Contributor
timestamp: July 30, 2023, 04:50:31 pm
content: Quote from: djsb on July 30, 2023, 07:33:01 amLink see first post.Updated Kicad files ask Josh...

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 30, 2023, 05:01:09 pm
content: Quote from: Martin72 on July 30, 2023, 04:49:51 pmThere's a plastic enclosure that covers that area for the heater block. MKS won't likely be a good idea/fit there. You can try when you get the 3D printed stuff in and see how tight it is.Sorry, I'm not sharing my kicad files. I blew a lot of time on them, and I refuse liability for any errors anyway. 😉

author: Martin72
author_rank: Super Contributor
timestamp: July 30, 2023, 05:04:15 pm
content: QuoteOr make it a litle bit deeper.QuoteEehhh...

author: Martin72
author_rank: Super Contributor
timestamp: July 30, 2023, 05:19:19 pm
content: Pic showed wrong place (C30), now on the right place.

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 30, 2023, 06:27:39 pm
content: So now it's going to be compressed between U9, and the 3D part that won't fit if you don't change it. Not worth it. If you're going to spend $500 on parts to make a VA reference, spend the $4 or 40 cents to get the appropriate part. The entire design is only as strong as the weakest point you introduce.

author: Martin72
author_rank: Super Contributor
timestamp: July 30, 2023, 06:39:10 pm
content: Well,As long as not all ICs are avaible yet, we´ll have all the time to think about it.BTW, the AD8676ARZ we need is avaible in Ebay, from a chinese vendor....Fake or not..

author: KungFuJosh
author_rank: Super Contributor
timestamp: July 30, 2023, 06:41:14 pm
content: I'd be patient, same statement as above regarding introducing weaknesses into your expensive project.I also found somebody who would sell the expensive chip for $70, but I don't trust them. 🤷

author: Martin72
author_rank: Super Contributor
timestamp: July 30, 2023, 06:50:12 pm
content: Yes, I also think I will first equip everything I already have and then we'll see.As mentioned, tomorrow the USB port and the chokes soldered, then the thing with the display and if that has all worked, you can continue with the housing and eventually the missing ICs are available again.

author: Kleinstein
author_rank: Super Contributor
timestamp: July 30, 2023, 07:05:33 pm
content: Quote from: Martin72 on July 30, 2023, 06:39:10 pmThe AD8676 is not that unique. There is a very good chance that one could substiture with a similar part that is better awailable, like AD8672 or ISL28227 or depening maybe also slower chips.

author: Martin72
author_rank: Super Contributor
timestamp: August 01, 2023, 07:31:20 pm
content: USB port and the coils, soldered at work...Looks good ( bad light for the pics) and I could start soldering the avaible components.Maybe next weekend, until then a part of the Digikey order should have arrived, with the sinfully expensive 0.01% 0.2PPM resistor in 1206 format, which alone costs almost 15€, I ordered then also only one...Heater pcbs are shipped.

author: mwb1100
author_rank: Frequent Contributor
timestamp: August 01, 2023, 09:35:12 pm
content: I couldn't tell if you got the programming cable situation straightened out. If not, 4dsystems has detailed schematics for the uUSB-PA5 which is a small PCB version of the programming cable.-https://resources.4dsystems.com.au/datasheets/accessories/uUSB-PA5/The schematic shows that the RESET pin of the programming cable is controlled by DTR through a transistor. If DTR is asserted (5V) then the RESET pin is routed to GND. So I don't think you'll be able to just use an off-the-shelf USB-to-TTL serial cable. You certainly can't use a serial port that's using RS232 voltage levels.

author: Martin72
author_rank: Super Contributor
timestamp: August 03, 2023, 08:59:07 pm
content: Today the digikey order arrived, except the MAX6350 and AD5791 "of course".But they will be delivered later, if in stock - So I can not forget about them.I don't have to worry about the two AD8676 anymore, thanks to a very nice user.So today the missing resistors and capacitors arrived.C33 is now a foil with 1µF.The resistors look quite unspectacular, for that they were so expensive.The 100 Ohm (R10)with 0.02% tolerance and 0.2PPM Tempco has very narrow solder joints, the 1K (R16) in 0805 case and with 0.01% tolerance looks like any other.And I'll take the board to work again tomorrow, there is one more component after the L1/L2 and USB port that I can't solder at home:U3...(because of the exposed metal back)Hopefully it will work tomorrow, I wanted to solder at home this weekend what I already have.

author: Andreas
author_rank: Super Contributor
timestamp: August 03, 2023, 09:15:04 pm
content: Quote from: Martin72 on August 03, 2023, 08:59:07 pmAD586L or MAX6250A play in the same ball park as MAX6350 (especially if the heater option is populated).After my experience the AD586 has better long term stability than the MAX references. (at least in DIP8 package).with best regardsAndreas

author: Martin72
author_rank: Super Contributor
timestamp: August 03, 2023, 09:38:29 pm
content: Thanks for the tips and hints, I will keep them in mind.The current project is well advanced, I have all the components except the reference and the dac IC, I have the board with appropriate layout, I will finish accordingly and see how it performs.

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 03, 2023, 10:15:38 pm
content: Quote from: Martin72 on August 03, 2023, 08:59:07 pmYou don't have hot air or an SMD PCB heater?

author: Martin72
author_rank: Super Contributor
timestamp: August 03, 2023, 10:40:30 pm
content: No Sir..At work we have reflow, infrared, damp heat, etc., so I don´t need cheap solutions at home which could damage the part easily.

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 03, 2023, 11:07:30 pm
content: It's not usually thesolutionthat damages the part. 😉

author: Martin72
author_rank: Super Contributor
timestamp: August 04, 2023, 07:57:34 pm
content: With the cheap hot air stations or these homemade reflow ovens, it's simply a gamble and not a solution and as long as I have access to proper tools, I'll use that.The colleague had already soldered the chip today, so I could take the board home again.Earlier I have first marked the positions, pin 1 of the ICs, anode of the diodes, plus of capacitors ...Today also the USB to serial converter arrived(a second, the first order was getting "lost"..)Would have been nice, there would be a small drawing of what exactly you can do with the small switches...

author: mwb1100
author_rank: Frequent Contributor
timestamp: August 04, 2023, 10:25:30 pm
content: Quote from: Martin72 on August 04, 2023, 07:57:34 pmI found these diagrams which should get you going:

author: Martin72
author_rank: Super Contributor
timestamp: August 05, 2023, 07:31:44 pm
content: Today I wanted to solder all ICs that I already have here, that worked so far well until I opened the bag where U7 is packed inside:

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 06, 2023, 02:36:12 am
content: Quote from: Martin72 on August 05, 2023, 07:31:44 pmHmmm, that sounds familiar... 😉Quote from: KungFuJosh on July 25, 2023, 10:46:10 pm

author: JohanH
author_rank: Frequent Contributor
timestamp: August 06, 2023, 10:11:28 am
content: Quote from: Martin72 on August 05, 2023, 07:31:44 pmIf that's SOIC vs TSSOP you might be able to bodge it in an emergency. If pinout is the same. Bend up corner pins. Solder the center four pins. Then four small wires for the corner pins. I've done something like that once.

author: Martin72
author_rank: Super Contributor
timestamp: August 06, 2023, 10:19:36 am
content: Hi,I had already thought about that and I will do the same for another project (curvetracer).But not for this one, especially since the chip is abundant, even in the SOIC housing.But I am currently collecting something that I can still order, just the IC alone hardly makes any sense.

author: DavidKo
author_rank: Frequent Contributor
timestamp: August 06, 2023, 10:32:35 am
content: You can modify the PCB to accept both IC packages on another side seems to be place. You only need to order new PCB.

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 07, 2023, 02:14:07 pm
content: This appears to be the correct package:https://www.mouser.com/ProductDetail/584-AD8276BRZI'm gonna look over those chips and update the BOM. I already updated my project.

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 07, 2023, 02:48:32 pm
content: AD5791 BOM says SSOP, all versions in reality say TSSOP.PZT2222AT1G is the model specified, but mouser says SOT-23-4, and shows SOT-23-3 in the photo (3 pin is correct). 🤷I updated the BOM again (attached).One other part number was off, but I don't know if that matters or not. It said 2N7002-T1-E3 instead of 2N7002E-T1-E3.As I said before, this is still not fully verified. 😉

author: Martin72
author_rank: Super Contributor
timestamp: August 11, 2023, 05:24:13 pm
content: Heater pcb finished - And it works.Initial (and max) current appx 257mA, then falling, rises again when the pcb is getting "colder", so the regulator circuit is ok.

author: Martin72
author_rank: Super Contributor
timestamp: August 12, 2023, 09:47:29 pm
content: I have now tried the adapter - With zero success.Does a RESET signal really have to be present, or have I already destroyed the module before, that is the question.What is good:The adapter has the DTR signal out as a pin, so you could put the reset circuit in between.For this you would have to know what values the RC part has and if the transistor is a PNP or NPN type.It's a pain in the ass to spend almost 40€ for the original programming adapter, but if I don't get further tomorrow, I will order it.And if it works then, examine the adapter more exactly and make it public, so that others do not have to spend the money.

author: BmaxTom
author_rank: Contributor
timestamp: August 13, 2023, 04:24:58 pm
content: I used the Waveshare FT232 TTL module and connected it to the original programming adapter as follows. The green wire is the DTR signal. I set the voltage level to 5V. With this it worked for me.

author: BmaxTom
author_rank: Contributor
timestamp: August 13, 2023, 04:44:42 pm
content: I've only just found this thread. I built the Elektor Voltage Current Calibrator about half a year ago.If the original circuit boards are used, the components on one side are too close to the Hammond housing and can cause a short circuit.

author: Martin72
author_rank: Super Contributor
timestamp: August 13, 2023, 05:43:32 pm
content: Hi Tom,Glad to hear that you already did itIsolation:Yepp this is known, I´ll isolate the edges with capton foil when assembling the board into the housing*.Display:I made it...I wondered why the RX/TX leds on the adapter never blinked when the program scanned the port.So I connected my scope to the channels and lo and behold, nothing...Nothing at all.Either the adapter is defective or the configuration was not right yet.It was the latter....the DIP switch must be set as shown in the picture, then it works.(thanks again to mwb1100 for thediagrams, it must the first configuration.)So you don't have to buy an expensive adapter from 4D systems...Very good.Now I have to buy a micro SD card.*) If everything goes well afterwards, I will probably take another housing.

author: Martin72
author_rank: Super Contributor
timestamp: August 14, 2023, 10:03:22 pm
content: Mouser now have the MAX6350CSA on stock again, order it and the U7 in the right package..So the AD5791 DAC is the only thing missed, will be in stock in september, october.But like the other ICs from AD, there are at least two types, A-grade and B-grade.Where B-grade have the "better" specs in some cases.

author: Martin72
author_rank: Super Contributor
timestamp: August 16, 2023, 07:52:52 pm
content: QuoteArrived today, I then formatted it to FAT16.What I then need to figure out is which files need to be saved to the SD card and which (or which) file is intended for programming the diablo processor.At the moment I think that the content of the USD_files folder belongs on the card...I will try the days, what belongs to what.

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 16, 2023, 08:06:14 pm
content: The Software folder with the En_course subfolder is the software that would get programmed with the WORKSHOP4 4D Systems programmer software.The USD_files folder is what goes on the microSD card.

author: Martin72
author_rank: Super Contributor
timestamp: August 16, 2023, 08:15:06 pm
content: Sounds logical, we'll see.

author: Martin72
author_rank: Super Contributor
timestamp: August 17, 2023, 09:22:08 pm
content: My mouser order arrived today at work, now the DAC is the only thing missed.And U7 have now the right size...Soldering it and the MAX6350CSA+ in a break, like the tantalum capacitors and the one film cap.We have also a 3d printer here, so chances are good that I could make the frontplate and the housing for the heater at work.Next weekend I´ll try to program the display.

author: Martin72
author_rank: Super Contributor
timestamp: August 18, 2023, 09:31:29 pm
content: QuoteCouldn´t wait, did it today in the evening..Success..Tried several times, several things, at the end it was easy:- You musn´t open the 4D Workshop main program.- In windows start, click on the 4D mainfolder and start "Program Loader" (connect the display before via usb adapter to the pc/notebook)- Choose the right com port.- Select the Software ->En_cours folder, the executable file will be displayed.- Click to OK to start programming- That was it for the cpu part.SD-Card:- Must be formatted in FAT16, I´ve bought extra a 4GB card for it and formatted it via windows command line.- The 4D formatting tool (you can format cards above 4GB with it) won´t work here.- Copy the files from the USD folder directly to the cardI did this after the programming, before, while the first start of the display, the card was empty and you see only a "+" symbol and a dot on it.After all I´ll test the display and tap the +/- fields - It works...So this is finished, next monday I´ll solder the rest on the pcb (loose one 10µF tantalum, must look here at home if I got another).Martin

author: KungFuJosh
author_rank: Super Contributor
timestamp: August 18, 2023, 11:05:21 pm
content: Nice. That's pretty typical regarding the programmer. Programmers and Development environments are often bundled together, but actually separate.

author: Martin72
author_rank: Super Contributor
timestamp: August 18, 2023, 11:21:44 pm
content: Oh yes, I´ve studied the manual before, but didn´t find a thing about it.BTW, another reason why the display is so expensive:Not only it is "intelligent" (controller for other things), the display itself got the highest selection grade.Only 0...4 max. dead pixels.

author: Martin72
author_rank: Super Contributor
timestamp: September 21, 2023, 09:15:39 pm
content: Finally in stock:https://www.mouser.de/ProductDetail/Analog-Devices/AD5791BRUZ?qs=NmRFExCfTkEaSRRmY4%2Fg1g%3D%3DAnd ordered, should arrive next week - The last one I need for completing the circuit...

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 03, 2023, 03:17:48 pm
content: Did you build this yet? I'm curious how it came out.

author: Martin72
author_rank: Super Contributor
timestamp: October 03, 2023, 05:38:43 pm
content: Hi,Unfortunately not yet.The chip has arrived and is together with the board on the table at work.I wanted to supply the board with voltage to see if everything is ok before I solder the most expensive part of the circuit.Too much to do the last few days.I think, soon it will be so far.

author: Martin72
author_rank: Super Contributor
timestamp: October 04, 2023, 08:34:52 pm
content: QuoteAnd I already know how, I haven't soldered in the PS1 converter yet, so I can connect two power supplies with current limiting to the +/-15V inputs and carefully boot up....I am quite sure that I have observed the polarities of all components, but "thanks" to the missing markings on the board, something may still have gone wrong, hence my cautious approach.

author: Martin72
author_rank: Super Contributor
timestamp: October 09, 2023, 06:36:28 pm
content: Did it today..No anormalies....Wait a minute..Why do I measure 2.5V on the output of the MAX6350Because it´s a 6250...Overlooked this, now I´ve ordered the right one - and another part which is wrong:PS1....In my "old" BOM its a single 15V, we need a dual 15V...Mouser-Nr.:490-PEME2-S5-D15-Sis the right one(if you don´t have your BOM updated @Josh)Martin

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 09, 2023, 07:48:19 pm
content: Quote from: Martin72 on October 09, 2023, 06:36:28 pmYou didn't order700-MAX6350CSAfor the 6350? That's what's on the BOM.If the single output is wrong, then the original downloaded BOM is wrong too. The BOM that comes with the kit says "IH0515SH" - which is single output. Are you sure about that part change? Did you also verify the footprint?Thanks,Josh

author: Martin72
author_rank: Super Contributor
timestamp: October 09, 2023, 07:56:51 pm
content: I know now what went wrong...The MAX I´ve googled instead of using the BOM, the link to mouser brings you to the 6250 - Although in my search I´ve typed 6350...Thank god the 6350CSA+ is avaible.(There is also a 6350CSA+T, with0.5ppm/C° avaible, but with a smaller package.)QuoteAbsolutely.Look at my post, the pic:https://www.eevblog.com/forum/testgear/elektor-voltage-current-calibrator-project/msg5094678/#msg5094678Plus the op-amps on this board are needing a dual-supply(output of the reference is +/-10V)Martin

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 09, 2023, 08:17:52 pm
content: Oh well, the original BOM screwed us again. Well, mostly you since I didn't order shit yet. 😉

author: Martin72
author_rank: Super Contributor
timestamp: October 09, 2023, 08:26:55 pm
content: If you wait a little longer to run my reference, we'll have all the bugs worked out.My loss, your gain.

author: tautech
author_rank: Super Contributor
timestamp: October 09, 2023, 08:28:31 pm
content: Quote from: Martin72 on October 09, 2023, 08:26:55 pmMartin the guinea pig.Having trouble with that image now......

author: Martin72
author_rank: Super Contributor
timestamp: October 09, 2023, 08:31:09 pm
content: Someone has to do it...

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 09, 2023, 09:43:15 pm
content: Quote from: Martin72 on October 09, 2023, 08:26:55 pmThat was always the plan. 😉😉🤣🤣🤣

author: Andreas
author_rank: Super Contributor
timestamp: October 10, 2023, 05:06:51 am
content: Quote from: Martin72 on October 09, 2023, 06:36:28 pmHello,Shure?the MAX6250 is also a 5V reference. (with 2 ppm/K)The 2.5V versions are MAX6325 or MAX6225(A).I would check the supply voltage of the reference on Pin 2. (Minimum 8V necessary).with best regardsAndreas

author: Martin72
author_rank: Super Contributor
timestamp: October 13, 2023, 05:46:55 pm
content: It works !!Soldered up the DAC at work today, then took it home and plugged in the display and runs right out of the box.+10V/-10V, 0-40mA, no problem...Very good.Quick and dirty set up, took a few pictures.Soon there will be nicer pictures....But the main thing is that it works already.@Andreas:Yes, that was completely the wrong one, I was wrong, it was a 6225....

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 13, 2023, 06:19:15 pm
content: Awesome!So it seems to be accurate only within 3 digits, or your meters are. I'll assume the meters are more accurate. Are you going to have it calibrated? Does it have full adjustment settings?

author: Martin72
author_rank: Super Contributor
timestamp: October 13, 2023, 06:38:26 pm
content: Hi,I just put it into operation for the first time, without any other actions.These will follow when the board, heater and display have been moved into the case.I first wanted to know if it works at all....

author: skander36
author_rank: Frequent Contributor
timestamp: October 14, 2023, 06:47:04 pm
content: Hard to compete with Ian's reference.On Mouser using BOM from Josh the price is 366.67 E. And this is without hammond box, and pcb (which I have them ordered about two years ago when I try to start building the project but stoped because of the lack of DAC on market).At about the same price you get a ready calibrated and very stable source with PDVS2 mini.Also this project need calibration with a metrology grade tool.Just DIY spirit justify spending so much for this project.

author: Martin72
author_rank: Super Contributor
timestamp: October 14, 2023, 07:11:25 pm
content: QuoteExactly.And I still have fun doing it.Apropos hammond housing:I must have got a copy, which is rather too narrow in terms of dimensions, because a few components threaten to collide with the grooves ... I'll have to think of something else.

author: skander36
author_rank: Frequent Contributor
timestamp: October 14, 2023, 07:29:45 pm
content: Quote from: Martin72 on October 14, 2023, 07:11:25 pmI think this is the spiritWhen I ordered I used the code from the project (HAMMOND 1455J1201BK) but is the same situation. I think the problem is from pcb design, the author should've leave a clearance between the metal case and the component zone, 2 more mm would be enough.

author: Martin72
author_rank: Super Contributor
timestamp: October 14, 2023, 08:08:47 pm
content: I have taken the information about calibration and the benefits of the heater from the website and put it into a text document.Edit:QuoteThe DAC is available again.It was before, but the "very cheap" version is somewhat "worse" in terms of performance.The same with the voltage reference, Max6350 is not equal to Max6350.The CSA+ type is the one with the 1ppm, others are above, one has 0.5PPm (CSA+T).Then the OP amps, "A" grade is in this case the "worse" variant, I have all in "B" grade.Then I will soon look for a permanent place for the board and keep it in operation for more than a month...

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 14, 2023, 08:18:21 pm
content: Don't believe my old attachment BOM without verifying first. I'll export a new one eventually.Yes, it's 100% the spirit of DIY that makes this project desirable. My $20 AD584L voltage reference covers my needs in reality.

author: Martin72
author_rank: Super Contributor
timestamp: October 15, 2023, 05:44:43 pm
content: Hi,The 3d printing parts I´ve ordered now from here(website only in german)https://www.3ddesign24.de/Well, let's see if they will also grumble because of the partial thinness, like JLPCB.

author: Martin72
author_rank: Super Contributor
timestamp: October 15, 2023, 09:30:52 pm
content: Hm-Hm...The battery according to BOM I could not get at Mouser, had not interested me at first.But now...Searched and found at Buerklin:https://www.buerklin.com/de/p/mikroelektronika/akkupacks/mikroe-1120/74S4080/OK, 2-pin connector, that will be connector J2 on the board.But then why the multi-pin header J1 on the board with the note "Battery Boost Option" ?A look at the schematic reveals that something else must be connected to the connector, the battery on J2 alone is not enough.Especially not the voltage, the 3.7V are not enough for PS1.So an additional circuit is probably connected to J1, in the schematic it will be called "Step up charger"But there is nothing to read about it in the documentation...

author: Martin72
author_rank: Super Contributor
timestamp: October 28, 2023, 07:04:19 pm
content: Earlier glued the Heater PCB to the designated place on the motherboard, using thermal adhesive.When it has set, the heater housing is attached.The two housing parts were also the only thing that was in order from the delivery of the online 3d print provider.The two front parts I have criticized, my brother with his 200 € printer would have done the same or better.Now better manufactured come.

author: Martin72
author_rank: Super Contributor
timestamp: October 29, 2023, 06:47:06 pm
content: Cured overnight, holds bombproof.The rest is easy, soldered wires and put the housing on it.Then switched on again, everything still runs, the area is warm and in the display is also no longer a warning message.From the wiring diagram, the heater is supplied directly via the usb connection, past the switch.That is, he heats even if the reference is off, which makes sense.Next steps are the final installation in the housing and then let age.

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 17, 2024, 11:08:36 pm
content: Did you ever finish this? I might actually make one soon.

author: Martin72
author_rank: Super Contributor
timestamp: January 17, 2024, 11:48:30 pm
content: Hi Josh,I'm still struggling a bit with the housing.The 3D parts that were delivered later and manufactured again are just as badly made as the first ones.Then I wanted to install 4mm safety sockets, but there is only enough space for the normal 4mm banana sockets, which I don't like.However, I have planned to simply run the module soon because of aging before calibration(at least for a month).And in the meantime I might buy another, somewhat more spacious housing.

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 18, 2024, 12:38:11 am
content: I dunno if you looked at my cal chart in the LCR thread, but the two voltage sets are my two different Siglent DMMs. The 3055 is the one that was high, and the X-E was the one that was in spec for the LCR. So I want to get a better reference to see which one is actually closer.

author: Martin72
author_rank: Super Contributor
timestamp: January 18, 2024, 12:56:48 am
content: I understand that and you won't be able to avoid having this reference calibrated externally, just like me.Because it has deviations which are in the nature of things.The manufacturer recommends a multimeter with at least 6.5 digits for calibration (I have one), but in order for me to be able to test my multimeter with it, a calibration with at least 7.5 digits would be necessary.We have seen that the reference from the first start is certainly not as correct as it could be.And the aging only serves the purpose of being able to take the later calibration "seriously" in the sense of not having too many fluctuations afterwards.The benefit for you as a later rebuilder will be how accurately the reference can be calibrated.If it can keep to the recommended 10ppm, you can start rebuilding it, otherwise I would leave it alone.So look forward to the next few weeks with me.

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 18, 2024, 01:25:31 am
content: Yeah, that's also why I'm torn between this project and purchasing an already (actually) calibrated voltage ref. This project would be the more fun option.Edit: I just ordered the vref10-001 r9. Significantly less expensive, calibrated, and includes 2 years of free calibration. I'll wait on this project until necessity or boredom bring it on. 😉

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 21, 2024, 07:02:05 pm
content: I think my lazy idea to get that 10V ref is crap. I need the versatility this project has, and I still need it calibrated. So I think the first thing I'm going to do is let my 3055 run for a week or two then send that in for calibration and compare my meters. If it's still questionable, then I'll probably build this project. I'd be more inclined if the housing wasn't an issue...though I do have a friend I could bother to make the housing design better.Right now, my X-E is more stable than the 3055.

author: Martin72
author_rank: Super Contributor
timestamp: January 21, 2024, 10:35:41 pm
content: That is the current status.The 3D parts and the cover for the display do not fit, the bolts are too thick for the openings (well, you could drill them out), overall the housing provided is very tight.I am looking for a slightly larger housing.

author: skander36
author_rank: Frequent Contributor
timestamp: January 21, 2024, 10:36:57 pm
content: Quote from: KungFuJosh on January 21, 2024, 07:02:05 pmWith less money than you spend on this project, you can get PDVS2 mini, which is already calibrated and that has stunning stability.I was already tried to make this project but I have made the correct choice at the right time and I don't regret.

author: Martin72
author_rank: Super Contributor
timestamp: January 21, 2024, 10:55:04 pm
content: QuoteWe'll know if that wasn't regrettable when I get this reference back from calibration.But yes, a finished product is of course tempting, especially when it's cheaper.In addition to the "fun" of building it myself and learning in the process, I also found the possibility of generating a reference current tempting.Oh, we'll see, of course I hope it was worth all the money.

author: Martin72
author_rank: Super Contributor
timestamp: January 23, 2024, 10:57:14 pm
content: The housing has arrived.Well, blue is not the color of choice, but it's not that terrible.I got to work and created a new front panel in the front panel designer, I can upload the file to the store and get it in about a week.I'm currently thinking about aluminum "nature" or blue...

author: The Soulman
author_rank: Super Contributor
timestamp: January 23, 2024, 11:41:47 pm
content: Nice, what brand/model enclosure is that?

author: Martin72
author_rank: Super Contributor
timestamp: January 23, 2024, 11:49:24 pm
content: https://www.amazon.de/dp/B0CB8GXMSB?psc=1&ref=ppx_yo2ov_dt_b_product_detailsYou can also get this housing from other suppliers on amazon in different sizes.For the money, this case is neatly constructed and made mainly of metal.

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 24, 2024, 12:28:09 am
content: Quote from: Martin72 on January 23, 2024, 10:57:14 pmHmm, that's a good point. I could make my own panels on my laser. 🤔

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 24, 2024, 05:42:57 pm
content: Was PEME2-S5-D15-S the part you used for PS1? Did it have 5 pins? I'm assuming that if that's the correct part, then the Mouser pictures are wrong?Thanks,Josh

author: Martin72
author_rank: Super Contributor
timestamp: January 24, 2024, 06:28:50 pm
content: Hi Josh,Yepp, it´s the PEME2-S5_D15-S....Martin

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 24, 2024, 06:50:24 pm
content: Thanks. Mouser seriously needs to fix their images.

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 24, 2024, 07:30:54 pm
content: You said the Hammond enclosure was too small. In which dimension?This is the original part number from the original BOM:1455J1201 1455J1202 L:120 W:78 D:27If it's too narrow, the 1455K1201/1455K1202 increases depth to 43mm. There are other options for increased dimensions:https://www.hammfg.com/electronics/small-case/extruded/1455Thanks,Josh

author: Martin72
author_rank: Super Contributor
timestamp: January 24, 2024, 08:46:28 pm
content: Hi Josh,The inner width of 75mm +/- 0.5mm is a very "precise fit", as the circuit board also measures 75mm.You have to stretch the housing a little when inserting the circuit board, but of course it holds firmly.The main problem is part of the positioning on the board, an area is a little under 3mm from the edge of the board - this can lead to collision problems, as the grooves inside the housing protrude approx. 2.5mm.The component height of the capacitors in the area was also a problem for me, which I could only solve with a lot of "dremeln".The 27mm depth, on the other hand, is only a problem if, like me, you want to use the larger 4mm safety sockets, otherwise not.Martin

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 24, 2024, 08:57:39 pm
content: So it sounds like for the best options, I should reposition those components with proper clearance from the board edge, and switch to 1455K1201/1455K1202 for the extra depth in case I want safety sockets.Edit: Actually, looking at my board version. I already reduced the size to 73.5mm, but I could easily shift everything down a couple mm. I think I'll slightly increase it to ~74mm, and shift everything for clearance.

author: Martin72
author_rank: Super Contributor
timestamp: January 24, 2024, 09:20:28 pm
content: If the ICs weren't so expensive, I would also put my hand on the design again...Be that as it may, I have now ordered the front panel in aluminum "natural", the blue was a bit too daring for me in terms of appearance.The housing isn't huge, but it's big enough to be able to install a stationary power supply - maybe I will.A little gag on the side:Not too long ago, I was looking for an electrical load that could provide small currents precisely so that I could compare current clamps in the mA range with it - but I already have a precision current source with deviations in the µA range...LOL.

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 24, 2024, 09:25:54 pm
content: I changed the board height to 74mm, and increased the clearance. There's over 4mm clearance from the closest component to the edge. It's hopefully safe now for either enclosure without any "improvements." 😉Quote from: Martin72 on January 24, 2024, 09:20:28 pmWhat else would you change?

author: Martin72
author_rank: Super Contributor
timestamp: January 24, 2024, 09:41:29 pm
content: I would implement mounting holes to be more independent from the housing and several testpins for the different stages for easier debugging.Further I would think about to "erase" the whole battery circuit as the heater is a real "current sucker".But first I want to finish this puppy.Martin

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 24, 2024, 10:02:50 pm
content: Quote from: Martin72 on January 24, 2024, 09:41:29 pmI haven't thoroughly looked yet, but there might already be some test points. I recall DRC mentioning VIAs only connected on one side, and not having any other purpose. One of those was on a +13.5V line, which I assumed was an intended test point.I'm probably skipping everything to do with the battery anyway, but I don't see a purpose in removing it from the board in case I ever change my mind about wanting it to be portable for 5 minutes. 😉

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 27, 2024, 01:47:57 am
content: What test points would you add? I want to see if there are any other changes I should make before ordering the board...again. 😉

author: Martin72
author_rank: Super Contributor
timestamp: January 27, 2024, 08:13:03 am
content: I would have to check the circuit diagram again, but in principle all voltages generated by the board (3V3, 10.5,V -10.5V, as well as the reference output of the MAX chip (5V).I think it is easier and safer to measure at such test points instead of measuring directly at the components with test probes.

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 27, 2024, 03:48:58 pm
content: Quote from: Martin72 on January 27, 2024, 08:13:03 amThat's what I figured. I know there's that via I mentioned for the 13.5V, I'll look again and see if there are already others hiding.

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 27, 2024, 08:05:34 pm
content: What do you think about this? I added test points for 3.3V, 5V, +/- 10.5V, and +/- 13.5V (wrote 10.5 instead of 10.49 to save space).

author: Martin72
author_rank: Super Contributor
timestamp: January 27, 2024, 08:41:15 pm
content: Nice.Ref_out is missing, but if I remember the circuit diagram correctly, we can measure this over a cap.

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 27, 2024, 08:53:21 pm
content: Quote from: Martin72 on January 27, 2024, 08:41:15 pmI'm confused. What point is Ref_out? Output has its own test point already, and the voltages marked REF are the same as the 10.49V test points.I added a few test points on the rear (for no reason 😉), and a better place to jumper the VIN + VOUT if not using a battery (ignore the 3D connector, I would jump directly).

author: Martin72
author_rank: Super Contributor
timestamp: January 27, 2024, 09:13:15 pm
content: QuoteI meant the output (pin6) of the reference (U9, Max6350).But I have just looked at the circuit diagram again, you can measure this voltage at C36, so an extra test point is not necessary.

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 27, 2024, 09:21:48 pm
content: Quote from: Martin72 on January 27, 2024, 09:13:15 pmAh, I see. I added one anyway. Thought it won't be so useful once the heater crap is in place.

author: Martin72
author_rank: Super Contributor
timestamp: January 27, 2024, 09:36:07 pm
content: QuoteThe heater board is on the back, but you're right, it would only be interesting for the first test.

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 27, 2024, 09:48:44 pm
content: Quote from: Martin72 on January 27, 2024, 09:36:07 pmYes, but the 3D printed heater enclosure covers that whole section. As you said, it's only useful for initial testing anyway.

author: Martin72
author_rank: Super Contributor
timestamp: February 03, 2024, 12:53:48 pm
content: My engraved front panel has arrived, in superb quality.It also fits perfectly in the case, and then there was something else in the package - I don't even know how they came up with it....

author: KungFuJosh
author_rank: Super Contributor
timestamp: February 03, 2024, 04:11:07 pm
content: What did you use for R9? It's 0Ω in the schematic. I'm probably gonna use RC0805FR-070RL.

author: Martin72
author_rank: Super Contributor
timestamp: February 03, 2024, 04:51:49 pm
content: I would have to look again in the delivery bills to see which type I ordered.Definitely a Zero Ohm.

author: KungFuJosh
author_rank: Super Contributor
timestamp: February 03, 2024, 05:13:35 pm
content: Good. I found one of the 10k part numbers pasted there by mistake. Dangerous BOMs. Oops. 😉

author: Martin72
author_rank: Super Contributor
timestamp: February 03, 2024, 05:46:42 pm
content: Yes, you can really only rely on the wiring diagram.I had looked through the delivery bills and then I remembered.I had forgotten to order it and took an 0R from Vishay from our laboratory stock,

author: KungFuJosh
author_rank: Super Contributor
timestamp: February 03, 2024, 05:50:54 pm
content: What part numbers are you going to use for your external connections?

author: Martin72
author_rank: Super Contributor
timestamp: February 03, 2024, 07:04:21 pm
content: If you mean the connections for the measuring device, these will be 4mm sockets from Hirschmann or MC Contact.https://www.conrad.de/de/p/sks-hirschmann-seb-2610-f4-8-sicherheits-laborbuchse-buchse-einbau-vertikal-stift-o-4-mm-rot-1-st-734907.html?refresh=true

author: Martin72
author_rank: Super Contributor
timestamp: February 03, 2024, 07:36:31 pm
content: I still had 2 sockets, very good.The 3D parts are still good for something, one frame is perfect as a spacer.It looks good with the front panel, but I still have some tinkering to do because the reference board has to be mounted on the base of the housing.It will be...

author: KungFuJosh
author_rank: Super Contributor
timestamp: February 03, 2024, 07:44:34 pm
content: Mouser has those too:https://www.mouser.com/ProductDetail/845-972355101Noice.

author: Martin72
author_rank: Super Contributor
timestamp: February 03, 2024, 09:34:38 pm
content: Ah, that's why I didn't find anything when I entered "Hischmann" in the Mouser search function....Same model, different brand.

author: Kean
author_rank: Unknown
timestamp: February 03, 2024, 10:46:43 pm
content: That front panel looks great.

author: KungFuJosh
author_rank: Super Contributor
timestamp: February 04, 2024, 12:05:41 am
content: Quote from: Martin72 on February 03, 2024, 09:34:38 pmIt's actually made by Hirschmann for Altec. It shows both logos if you open up the datasheet. I searched by the part number to find it.

author: Martin72
author_rank: Super Contributor
timestamp: February 16, 2024, 06:06:54 pm
content: Today I took "special tools" with me from work.These two (slightly rusty) wrenches are only used to screw the 4mm safety bushes properly.You insert the thinner one at the front and turn it slightly until it clicks into place, then use the larger one to tighten the nut.You can also do this with needle-nose pliers, but it's much easier and tighter this way.

author: Martin72
author_rank: Super Contributor
timestamp: April 14, 2024, 09:27:48 pm
content: Update:No update, I´m a lazy boy...Or better, time is not enough, but it is not forgotten.Several projects are currently in the pipeline:- Voltage Reference, installation in the housing and ageing before it is sent in for calibration.- 1kHz ultra low distortion oscillator:Installation in the housing, testing.- Arduino Curve Tracer:Finish assembling, then test.- ENOB test environment:Filter boards designed, still need to be assembled and tested.- New HMI for Hioki 5Mhz LCR:So far only collected ideasAnd a lot more....As I said, lazy boy.

author: KungFuJosh
author_rank: Super Contributor
timestamp: April 14, 2024, 09:36:55 pm
content: On the bright side, you'll probably have your SDS3000XHD by the time you finish all that. 🤣🤣

author: Martin72
author_rank: Super Contributor
timestamp: April 14, 2024, 09:41:34 pm
content: Do you know the foot massage scene in pulp fiction?The final punchline where Vincent Vega had Julius by the balls and how Julius reacted to it ?I´m Julius....

author: KungFuJosh
author_rank: Super Contributor
timestamp: April 14, 2024, 10:00:11 pm
content: Nah, I don't remember. Maybe I'll watch the movie again and get back to you. I could probably watch it a couple times before.......................... 😉

author: Martin72
author_rank: Super Contributor
timestamp: September 14, 2024, 10:28:38 pm
content: Months later...The operation was a success. I had to disconnect the display from the board and build both circuit boards separately, then connect them with wires.Pictures will follow later.I would leave the reference switched on permanently for a month, but I still wonder if that's necessary at all.The MAX6305 is in the “oven” and is kept at a constant temperature....does it still need to be pre-aged?

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 15, 2024, 12:05:47 am
content: Wouldn't hurt, right? Plus you can test the reliability of everything before you inevitably pay somebody to calibrate it.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 15, 2024, 07:47:19 am
content: Some burn in for the reference would definitely help. The pre-aging is not for the TC part, but for things like chip internal stress and early electronic effects. The oven may speed up the process a little, but a month is not really that long.Another effect that can come in is humidity and PCB stress. With the heat there will be PCB stress and the reduced RH will cause some slow settling. The humidity effect can be quite slow with a timescale of days to weeks. For ultimate stability it would make sense to have the critical ref. part power 24/7. It is still the question if than a more classic heated reference like LM399 would have made more sense.

author: Martin72
author_rank: Super Contributor
timestamp: September 15, 2024, 09:07:27 am
content: The whole thing is very much based on the AD reference board.If all this turns out to be unsatisfactory, you can always switch to the “original”.But I hope it goes well, because it was expensive enough as it was.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 15, 2024, 09:22:57 am
content: The design looks OK for short term stability, noise and linearity. However it is not a really good long term reference. Within this limitation it can still be working well.

author: Martin72
author_rank: Super Contributor
timestamp: September 15, 2024, 03:35:02 pm
content: We'll see what it can and can't do.I had just turned it on and changed the value until the Brymen displayed 2.5V - that's the offset that you have to compensate for afterwards.However, I will only do that next month or the month after, until then the reference is allowed to run non-stop for a month together with the SDM3065X.I first wanted to take it to work and connect it to a UPS, maybe I'll do that too.In just under 2 months, we will have a calibration of all multimeters in-house. If the lab should bring their 8.5-digit meter, I'll ask them if they could leave me alone with it for an hour.

author: mawyatt
author_rank: Super Contributor
timestamp: September 15, 2024, 04:51:44 pm
content: Consider cycling the power on and off in the early stages of long term operation & testing. Use a rate that allows things to fully warm up then fully cool down to ambient. This relieves some of the mechanical stresses from the PCB build and mounting/cases assembly, and also taxes the components more than just constant operation at a fixed temperature.This was often implemented in aerospace/military equipment as temperature cycling. Recall a survival radio where this test uncovered a flaw where the temp cycling would cause the moisture in the potting compound to condense out on the surface of an alumina substrate. The moisture would collect salts on the substrate surface and osmosis would pull the moisture under a decoupling chip cap which had Vcc across it. Dendrites formed under the chip cap and eventually shorted Vcc, causing a radio failure. Took awhile to figure this out, as at first the chip cap was thought to have failed, only to find after removal they were fine and the short was gone as the dendrites were sucked back into the molten solder upon chip removal. Eventually the problem was found and source was traced to moisture contaminated potting compound.This cost a bundle with recall/rework and even worse when a user needed the radio for survival comms it could failSenior management tried to hide the problemBest,

author: dazz1
author_rank: Frequent Contributor
timestamp: September 15, 2024, 08:36:04 pm
content: HiI have updated the BOM with working links and current prices.The cost is driven by just two parts, the:LCD and,20bit DAC.The BOM doesn't include the heater option.I have not investigated whether a programmer is needed for the LCD.

author: Andreas
author_rank: Super Contributor
timestamp: September 16, 2024, 05:59:16 pm
content: Quote from: Martin72 on September 14, 2024, 10:28:38 pmHello,my 2 MAX6350 samples (in DIP8) were ageing ~10ppm/year for the first years.(now some years later they are at ~5ppm/year).https://www.eevblog.com/forum/metrology/how-to-age-a-max6350-voltage-reference-ic/msg3370012/#msg3370012The SO-8 package should be more sensitive to humidity changes (influence from the EPOXY PCB). Here heating may help to keep it more constant.If you really want a long term stable system you will need a reference in a CERDIP or Metal CAN case.with best regardsAndreas

author: Martin72
author_rank: Super Contributor
timestamp: September 16, 2024, 07:01:04 pm
content: In principle, I would “only” have to exchange the reference and leave the rest as it is.I would be interested to know what happened to the project:https://bastelblog.runlevel3.de/en/measurement/ltz1000a-1ppm-precision-voltage-reference/

author: dazz1
author_rank: Frequent Contributor
timestamp: September 17, 2024, 08:27:31 am
content: HiLooking at the Elektor Reference design, the 20bit DAC looks to be a weak link.The very expensive high spec version i accurate to 1.5bits, so it is really a 18.5bit DACThe expensive lower spec version is 4.5bits, so really a 15.5bit DAC.It would be possible to correct those errors using a 7.5 digit voltmeter and measuring the output voltage of every input value of each individual DAC. Only a million or so. Easy to automate.It would then be possible to create a lookup table that corrected every value. Ideally it should be possible to get 0.5bit accuracy.That method would require the source code (to modify) and changes to the Elektor design. Not really feasible.If you had a 7.5 digit meter, you wouldn't need the Elektor voltage reference. So as much as I would like to build the Elektor Reference, I don't think I ever will.

author: Kleinstein
author_rank: Super Contributor
timestamp: September 17, 2024, 04:50:05 pm
content: Things are not that easy with checking to a DMM. The DAC is fast, but the DMMs usually need a few seconds to get there full nominal resolution. In addition one may have to add some extra points for the full scale (for the reference) and maybe zero to allow for drift there.So 1 million points for a full test would some weeks. A problem is that the INL can be temperature dependent too. Things are likely better than spec at the ideal temperature where the DAC was adjustend / trimmed.It may be feasible to check at lest the major bit steps, like the upper 4 or 6 bits with way less points and a managable memory. The internal correntions can already complicate things, as the steps may be fussed out a bit.

author: mawyatt
author_rank: Super Contributor
timestamp: September 17, 2024, 04:56:38 pm
content: One could do a check and adjustment at the popular voltages such as 0.1, 0.5, 1, 2, 2.5, 5, 7.5, 10 Volts or whatever makes sense.Best,

author: Martin72
author_rank: Super Contributor
timestamp: September 17, 2024, 05:38:45 pm
content: QuoteThe AD chips used are all B-grade, i.e. the higher-quality variants.QuoteAt 10ppm, this was never an issue.If all goes well, you have a voltage available that is accurate to the 5th place.You can calculate the multimeter resolution up to which this will suffice.What is special about this reference is not necessarily the 5 decimal places or that you can set any value from 0V-10V.Rather, that you can change the polarity and that a fairly accurate current of up to 40mA is available.I was primarily interested in the technology behind it, how to build and calibrate something like this, and what is necessary to achieve stability.Of course it is expensive, almost €600 to date, but I have already paid significantly more in my life for things I learned the hard way.

author: dazz1
author_rank: Frequent Contributor
timestamp: September 18, 2024, 01:10:21 am
content: Quote from: Kleinstein on September 17, 2024, 04:50:05 pmA DAC is a voltage divider so measuring the input voltage (occasionally) and the output voltage would eliminate voltage drift errors.It would be necessary to automate the DAC calibration. It wouldn't really matter if it took weeks, or even months to check every value.The correction look up table would only require 5 bits max (for low spec DAC) for each value to store the corrections. Likely interpolation would further reduce memory requirements.The whole discussion is moot unless someone would take on the task of writing the software given that the source code is not available to amend (at least I don't think it is).

author: dazz1
author_rank: Frequent Contributor
timestamp: September 18, 2024, 03:57:41 am
content: Quote from: Martin72 on September 17, 2024, 05:38:45 pmWow, €600 is almost 2x the current cost. I like Elektor projects, but not enough to pay €600 or even €300 for this one. It is not that it isn't worth that much money. The software alone would cost much more to produce and the designer is not getting anything in return for releasing his project. It is that I don't have a problem that this project would solve.I'd still like to build one.

author: KungFuJosh
author_rank: Super Contributor
timestamp: September 18, 2024, 12:07:50 pm
content: Quote from: dazz1 on September 18, 2024, 03:57:41 amSame. 🤣

author: lownoise
author_rank: Contributor
timestamp: December 07, 2024, 04:07:33 pm
content: Reading this treat was very informative for me and motivated me to build a calibrator myselfThe assembly was relatively uncomplicated thanks to the tips from the contributors here, for which I would like to say thanksDuring the start-up I had a look at the program with the 4D-System Workshop4-Program and found some switches...- the heater function can be switched off, 1=on 0=off (so no error messages if not installed)- the labeling of the keys can be changed, I changed “Signe” to “+/-”There is also a display-off function realized with a counter (useful for continuous running for aging) - which is limited due to the 16bit number in millisecondsI have therefore added a new function based on the system-time, which can be set from 1min - 59min (0=off)If anyone is interested, you can load the program Calibrator.4Dg in Workshop4, adjust the parameters and then recompile/transfer (buttons in the top right-hand corner of the Workshop4 menu).https://4dsystems.com.au/products/workshop4/In the attached version, the heater is switched off and the display-off timer is set to 30 minutes (reactivating the display by touching it)...

author: Martin72
author_rank: Super Contributor
timestamp: December 07, 2024, 06:27:37 pm
content: Nice !

author: Martin72
author_rank: Super Contributor
timestamp: December 29, 2024, 08:27:45 pm
content: The reference has been in continuous operation for days. When a week of operation is over, I connect it to a timer to simulate operation-off-operation for at least another week.That should be enough.Then it gets interesting in terms of calibration.

author: Martin72
author_rank: Super Contributor
timestamp: January 01, 2025, 10:04:26 pm
content: QuoteOr not:Quote from: Excerpt from the calibration instructionsPhew, then I would have to let it run for another 3 weeks without a problem....The text was, however, before the oven, which constantly heats the voltage reference to approx. 55°C - should I still keep it running for so long?

author: KungFuJosh
author_rank: Super Contributor
timestamp: January 01, 2025, 10:23:50 pm
content: Of course. 😉Test stability once a week or something and see if anything changes.

author: Andreas
author_rank: Super Contributor
timestamp: January 02, 2025, 02:13:31 pm
content: Quote from: Martin72 on January 01, 2025, 10:04:26 pmHello,I would monitor the voltage output during ageing to see when it stabilizes.my experiences with MAX6350 (in DIP8-Package).It may need 50 - 100 days of operation until the ageing slope stabilizes to ~+10 ppm/year under constant conditions.After some years the slope goes down to ~+5ppm/year.(in my case they are in a ageing box which is warmer than environment and is heatet to 50 deg C every day during measurement for ~ 80 minutes).On power outage the Epoxy package of the reference soaks humidity from environment.After power outage I had a ~5ppm jump which stabilized after some days.Even under constant temperature you get some seasonal changes due to air humidity.In my case the humidity goes from ~40%rH in winter to ~70%rH in summer which affects the output.(see normalized Output from 65kHrs)with best regardsAndreas

author: Martin72
author_rank: Super Contributor
timestamp: January 10, 2025, 11:53:39 pm
content: Hi,For a week now, the reference has been in on-off mode, i.e. on for 2 hours and then off for 1 hour, through a timer, and this has been going on for a week now.Before that, it was constantly on for 11 days.On Sunday, I will create a way to measure the reference output and then leave the reference on constantly again, 24/7.When the internal 5V reference voltage appears stable, the “critical” point comes, the calibration.What makes this reference so special, and also justifies the rather high price, is that it is not only adjustable from 0-10V, but can also be switched from + to - and also provides a reference current of up to 40mA.The calibration effort increases accordingly.I would love to borrow a 7.5 or even 8.5 digit meter for it.But it is to be feared that the rent will end up costing more than sending my reference in for calibration.But I would rather do it myself.The temptation is, of course, to do a first preliminary calibration with my SDM3065X.The only thing that speaks against a “real” calibration with it is that it has an accuracy of 35 ppm and that the Siglent meters, although within the specifications, basically measure “less”, which somehow provokes the monk in me.But maybe I'll do it anyway, just to see how stable the reference is afterwards.@Josh: Since you already want to make changes to the original design, create a test point for the 5V reference, so that you and others don't have to tinker with it like I have to.

author: Kleinstein
author_rank: Super Contributor
timestamp: January 11, 2025, 09:14:31 am
content: There is not much lost in first doing a calibration to the own meter. With only the reference in a plastic case the accuracy is anyway not that high.The reference and rest of the circuit tend to get more stable over time. Another point is the possibility of still finding an early fault. The chance for a failure is larger in the frist year or so. Another point could be that with use one may find points one would want to add / change (e.g. a fan or changes to the case), that might effect the calibration. So if an official calibration is not needed, why rush it.

author: Martin72
author_rank: Super Contributor
timestamp: January 11, 2025, 03:27:22 pm
content: Hi,QuoteWould replacing the “oven” housing with a metal one, as well as housing the main board in an RF enclosure, help in this regard?

author: Andreas
author_rank: Super Contributor
timestamp: January 11, 2025, 03:50:20 pm
content: Quote from: Martin72 on January 10, 2025, 11:53:39 pmHello,take care that you do not have a output voltage shift by EMI when connecting any wire to the voltage reference.Especially when you have a noisy power supply (maybe due to a switchmode supply / LED lamp nearby).I already had up to 300 uV shift when suppling from RS232 interface from PC or several 10 uV with the reference battery supplied.I would put at least a 100 nF (Foil or ceramics) capacitor in parallel to the 2.2 uF at the output of the reference to minimize shift due to the test point.(of course a PI-Filter on every output would be better to avoid EMI shifts).see output power stage here as example:https://www.eevblog.com/forum/metrology/ad587lw-10v-precision-travel-standard/msg1449492/#msg1449492with best regardsAndreas

author: Martin72
author_rank: Super Contributor
timestamp: January 19, 2025, 10:26:03 pm
content: This week, I had the reference continue to run in on/off mode.So it had 11 days of continuous operation and 14 days of on/off operation.Now it is running continuously again, at least for another week.That should be enough, because I can't measure the reference voltage when it's installed and have to rely on the duration of the aging.A printed metal case for the oven is on its way, and I already have a metal case for the reference board itself.I'll actually start by using my SDM3065X to calibrate the reference to see how it goes and what the result looks like afterwards.And then we'll see.

author: Martin72
author_rank: Super Contributor
timestamp: January 27, 2025, 05:04:36 pm
content: QuoteThe printed case arrived today, looks good.I will leave the reference running until the weekend, then it will have been running for 5 weeks.And then I will install the new case parts.

author: spo256al2
author_rank: Newbie
timestamp: March 22, 2025, 05:50:45 pm
content: Hello Martin,How is run your Elektor calibrator, what about the stability?Rdgs

author: Martin72
author_rank: Super Contributor
timestamp: March 22, 2025, 07:07:44 pm
content: Hi,I will probably be able to present new findings in April.The reference and a multimeter have now been switched on permanently for weeks, I still have to modify the reference mechanically.I didn't have the time for that, but soon I will, and then I can post news.Martin