hybridfree/eevblog-posts huggingface dataset:
HOW TO USE THIS?! D7220AD! - Page 1
Forum section: electronics / projects

author: ali6x944
author_rank: Frequent Contributor
timestamp: January 28, 2016, 04:10:20 pm
content: HOW TO USE THIS?! D7220AD HGDC?

author: ali6x944
author_rank: Frequent Contributor
timestamp: January 28, 2016, 05:10:21 pm
content: https://drive.google.com/file/d/0B5vW-k7HbsL4WWlnRENzaFdtUWs/view?usp=sharingDATASHEET

author: ali6x944
author_rank: Frequent Contributor
timestamp: January 30, 2016, 05:21:57 pm
content: help me please!anybody please!

author: Paul Price
author_rank: Super Contributor
timestamp: February 01, 2016, 12:35:22 am
content: This chip is 35-45 years old(circa 1978?) and from what I've managed to find googling it, only NEC may have the rest of the 259-page datasheet in some dusty file cabinet, while only the first 3-pages seem to be available online. This chip is very complicated and you haven't a chance to even start to get it to work without spending days studying the full datasheet.Find some video controller chip that is newer, well-documented. It will work better, be easier to use, less expensive, less power-hungry, etc.Better yet, Google for Nextion simple to interface and very inexpensive displays.I would say your only chance would be to reverse engineer an early 8080 or Z80 CPM computer video board using this chip.

author: miguelvp
author_rank: Super Contributor
timestamp: February 01, 2016, 01:06:07 am
content: Hope this helps:http://bitsavers.trailing-edge.com/pdf/nec/uPD7220-uPD7220A_User_Manual_Dec85.pdfEdit: More here:https://en.wikipedia.org/wiki/NEC_%C2%B5PD7220Look at external links including Source code of driver for CP/M-86 as well as all of the Reference links (although some are dead links)For example the Intel GDC reference link is a dead link but looking for the file name pdf I found this:http://www.nj7p.org/Manuals/PDFs/Intel/230685-001.pdfEdit again:http://www.vintagecomputer.net/fjkraan/comp/virtlibrary.htmlLook for 7220 more docs in there (not the bubble memory one though) and one is in german with sample code from "MC Magazine 11/1986"

author: sarepairman2
author_rank: Frequent Contributor
timestamp: February 01, 2016, 06:33:54 am
content: omg

author: kripton2035
author_rank: Super Contributor
timestamp: February 01, 2016, 07:24:45 am
content: back to the future ...

author: miguelvp
author_rank: Super Contributor
timestamp: February 01, 2016, 07:27:25 am
content: People like to do retro builds, nothing wrong with it.Actually learning the legacy helps you understand better why it evolved the way it did.
How to use this connector? - Page 1
Forum section: electronics / projects

author: vinicius.jlantunes
author_rank: Regular Contributor
timestamp: June 19, 2016, 07:46:54 pm
content: Have any of you seen one of these before, whit this style connections for the cable? How do I solder / crimp / whatever the cable to it?I need to replace the plug on a pair of headphones and the guy at the store offered this "better quality" plug - I didn't really look much and took it as does indeed seem to be better that the others he had; I did not expect the terminals to be like this though, have no idea how to properly solder / connect the cable to it.Hopefully the pictures are enough. There are little holes beneath the black plastic piece with the metallic rings, one hole beneath each ring, that do not show well in the pictures.Thanks in advance!

author: vinicius.jlantunes
author_rank: Regular Contributor
timestamp: June 19, 2016, 07:50:03 pm
content: One more pic just for reference.

author: MarkF
author_rank: Super Contributor
timestamp: June 19, 2016, 08:50:50 pm
content: It looks like the Apple iPod plug that has stereo audio plus video and GND.

author: SeanB
author_rank: Super Contributor
timestamp: June 19, 2016, 09:03:37 pm
content: Tin a spot on each ring quickly, wipe off with solderwick and let it cool. then a dab of solder on the wire end and a quick application of heat to solder it on. Leave to cool properly between operations, or drown in IPA each time to keep the plastic from melting too much. They melt very easily, no more than 5 seconds of heat absolutely maximum at any time, then immediately cool down in the little puddle of IPA.

author: vinicius.jlantunes
author_rank: Regular Contributor
timestamp: June 20, 2016, 01:17:59 am
content: Thanks guys. So it is just solder, but very carefully not to meltdown the plastic. It will be tricky but will give it a go.Thanks!

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 20, 2016, 04:20:38 am
content: The big trap is that the outer shell is not ground. In fact, it's the microphone signal, the most sensitive to noise. Expect a lot of noise if you touch that conductive cover.

author: vinicius.jlantunes
author_rank: Regular Contributor
timestamp: June 20, 2016, 12:39:52 pm
content: hum, that's right, didn't realize it when looking up the pinout... you're right. I may just heat shrink the whole thing then, covering the metal.I'm also thinking of filling the cavity with some sort of resin after I'm done with soldering, otherwise it will be very flimsy.Thanks for all the advice.

author: ebclr
author_rank: Super Contributor
timestamp: June 20, 2016, 01:07:22 pm
content: Solda com Pasta de solda e Ar quente, fica acabamento descente
How to verify LVDS level compactibility between two ICS - Page 1
Forum section: electronics / projects

author: dssurya
author_rank: Newbie
timestamp: December 08, 2024, 04:16:35 am
content: Hi,I have got two LVDS support ICs , attached the voltage level specification. One IC LVDS supply voltage is 2.5V and other IC LVDS supply voltage is 1.8V. They mentioned differential voltage and input voltage range instead of common mode input for 1.8V supply LVDS IC. How to verify whether the mentioned voltage level supports other IC ?

author: langwadt
author_rank: Super Contributor
timestamp: December 08, 2024, 05:00:48 am
content: LVDS is LVDS

author: dssurya
author_rank: Newbie
timestamp: December 08, 2024, 05:13:23 am
content: Hi langwadt,I am asking about the voltage levels whether 1.8V IC specification meets the 2.5V IC? Refer the attachment

author: ataradov
author_rank: Super Contributor
timestamp: December 08, 2024, 05:59:06 am
content: LVDS is a well defined standard. It does not matter what is the supply voltage of the ICs. They will output and accept the same voltage levels on the LVDS lines.And in your case 1.8 V one seems to be adjustable for some reason, so you will need to configure it to output standard LVDS levels.The first IC is pretty much the standard LVDS, so you just need to adjust the 1.8 V one to be the same as the first one.

author: xvr
author_rank: Frequent Contributor
timestamp: December 08, 2024, 12:55:53 pm
content: Maximum output voltage from 2.5V LVDS is 1.375+0.450/2 = 1.6V. Maximum allowed input for 1.8 LVDS is 1.575V. This is 25mV of excessIt could work if you will be lucky enough

author: ataradov
author_rank: Super Contributor
timestamp: December 08, 2024, 04:06:28 pm
content: Where does 0.405 come from? 1375 mV is the maximum output voltage. The output is 1200 mV +/- 175 mV, so differential voltage is 350 mV, so it is just a standard LVDS.LVDS is LVDS no vendor will design it to be incompatible.

author: xvr
author_rank: Frequent Contributor
timestamp: December 08, 2024, 04:49:44 pm
content: QuoteFrom picture #1 of OP.QuoteIt's a maximum common voltage, not output (from picture #1)QuoteThis is 'typical' value from picture #1, not 'maximum'

author: ataradov
author_rank: Super Contributor
timestamp: December 08, 2024, 05:25:14 pm
content: Ok, similar numbers are present in two different places. So, if things go absolutely wrong on the 2.5 V side, it is technically would not be compatible with 1.8 side. I personally would not think about that twice for any volume project.
How to wash your oscilloscope! - Page 1
Forum section: electronics / projects

author: valvedoctor
author_rank: Contributor
timestamp: July 17, 2016, 01:22:10 am
content: Hey all, did a search on the forum and didn't see this little bit of Tektronix info around.This is an interesting read, which shows how Tektronix would wash their oscilloscopes in a wash booth, and it gives tips for cleaning it up yourself.Check it out!

author: tautech
author_rank: Super Contributor
timestamp: July 17, 2016, 01:50:33 am
content: Nice.There's plenty of scrubbing up of old Teks in this thread:https://www.eevblog.com/forum/testgear/vintage-tek-restoration-pictures-by-martin/And more cleaning methodologies in various threads here:https://www.eevblog.com/forum/repair/vintageclassic-renovation-techniques/

author: tautech
author_rank: Super Contributor
timestamp: July 17, 2016, 02:21:47 am
content: Quote from: wilfred on July 17, 2016, 01:59:11 amSimply, yes.Solid state CRO's are cleaner than VT CRO's but not by lots.I'd imagine that the higher the PDA voltage the worse dust attraction would be too although I have no evidence to support that assumption.In a vented case scope where the PDA cable was protected from dust gravitating onto it the cable still had a good layer of grime upon it, not good if you are in a humid climate.

author: Tom45
author_rank: Frequent Contributor
timestamp: July 17, 2016, 03:15:38 am
content: I'd think another (and possibly greater) factor is that a lot more air flow through the case is needed to dump the heat from a few dozen tubes. More air flow is more going to be more dust in the air passing through.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: July 17, 2016, 04:34:41 am
content: Quote from: wilfred on July 17, 2016, 01:59:11 am

author: Pjotr
author_rank: Frequent Contributor
timestamp: July 17, 2016, 08:03:52 am
content: Dust is also a bit "greasy" and sticks/bakes easier when heated or onto hot surfaces.
How to wire a 12v push button switch with led? - Page 1
Forum section: electronics / projects

author: filn
author_rank: Newbie
timestamp: September 14, 2023, 01:25:42 am
content: How to wire a 12v push button switch with led? The button switch has four wires, two LED light wires (the light on the button), and two switch wires. How can the LED lamp on device start when powered on?

author: PCB.Wiz
author_rank: Super Contributor
timestamp: September 14, 2023, 01:37:25 am
content: Quote from: filn on September 14, 2023, 01:25:42 amYou need to check the rating of the LED built in.Some have inbuilt resistors and can wire directly to 5V or 12V, and others are bare-leds thatmusthave additional current limiting resistor added.
how to wire pushbutton with spade terminals to an SMD pcb? - Page 1
Forum section: electronics / projects

author: k8943
author_rank: Regular Contributor
timestamp: March 20, 2019, 02:07:16 pm
content: Have been looking at reasonably chunky pushbutton switches (with 12 or 16mm mounting holes) and it seems that they tend to come with spade terminals.Browsing female spade connectors it looks like they are designed for pretty massive AWG (eg 10-20 AWG).If the objective is to wire to a neat little SMD pcb simply in order to effect the grounding of a pullup resistor on button press, what is the best way of doing this?Is one obliged to use a massive wire and then some kind of terminal block (screw?) on the PCB?Is there a trick for doing all of this with skinny 28AWG wires coming from a JST-SH connector on the PCB?Am all ears!ps the pushbuttons (4) will be in a plastic case and are supposed to be waterproof / splashproof hence not opting for on-board pushbuttons that peer through largish mounting holes. Unless there's a way to do that.....?
How to write an EDID into firmware video DAC - Page 1
Forum section: electronics / projects

author: rtomas
author_rank: Newbie
timestamp: November 18, 2024, 10:48:51 pm
content: Hello everyone,I'm currently working on a project involving a video DAC, specifically the Chrontel CH7101B, which is an HDMI-to-VGA converter. I'm looking for help understanding the proccess of writing a custom EDID into its firmware. Actually I already have a custom EDID ready but I have no idea how to write it into the DAC's firmware. Its HDMI has the standard i2c and 0x50 address for accessing EDID information but of course this does not allow writing. The DAC also provides an internal serial SPD and SPC but I have no idea how to use the same or if this is the correct method.If anyone here has experience with the CH7101B or similar video DACs, I’d be grateful for your insights and suggestions. Please feel free to ask for more details about my setup if needed.Looking forward to your guidance and discussion!Thanks in advance

author: sd
author_rank: Unknown
timestamp: November 18, 2024, 11:07:20 pm
content: Haven't used that IC, but you can use an I2C EEPROM to hold EDID. Or just hook up directly the VGA DDC to the HDMI DDC, if that is an option.

author: rtomas
author_rank: Newbie
timestamp: November 18, 2024, 11:19:15 pm
content: Mmmm not sure if the DAC allows to add an external EEPROM bypassing the internal firmware information. Cannot see it in the datasheet.Regarding to hooking VGA DDC directly to HDMI DDC is not an option because the device will be connected also to analog monitors and TVs that have not any EDID information.
How will new Roomba lawn mowers navigation work? - Page 1
Forum section: electronics / projects

author: bertoncelj
author_rank: Newbie
timestamp: September 07, 2015, 12:45:58 am
content: This year in Augustus, company who made indoors robot floor cleaners, bought right for 6,240-6,740 MHz frequency range, for their new outdoor robot lawn mowers. I assume this is for some kind of navigation purpose outside. I am asking now, does anybody know how this "new" outdoor navigation will work?

author: Sea Moss
author_rank: Newbie
timestamp: September 07, 2015, 03:47:14 am
content: I'm actually involved in similar research at my university.The same company released bots known as iRobot Create which we use in our lab.We basically put a Kinect camera on it and use the Kinect's ability to perceive depth for its navigation, I'd imagine they'd do something similar or use lidar. Currently, I believe the roomba uses lidar, but the problem with that is when you're out in a yard or somewhere that might not have clearly defined walls so then you could have navigation problems and the lawn mower could get 'lost' per se. Lidar basically works by bouncing a laser off the walls in front of you and calculating distance by how long it takes to get back. I honestly believe vector nav with the Kinect or something similar is the way to go, but this company has always been hush-hush about its technologies so we'll just have to wait and see when they release it.
How works FCC certification with modules - Page 1
Forum section: electronics / projects

author: Yaro
author_rank: Contributor
timestamp: March 17, 2016, 10:35:46 am
content: Hi all,I've recently read something about FCC certification and some of products like WiFi, BLE and RF modules claiming to have it. But I've some dubts about how FCC works. Here some questions I've:- I want to ask why some development board do FCC certification. Since FCC is necessary to use this boards in product that goes on market, this means that this boards aren't just developing boards?- If I use this RF modules(SMD versions) with onboard antennas and I solder them on another PCB, it's necessary to do again FCC certification on assembled board?About modules that don't include an antenna and this should be mounted on main PCB(like ceramic or PCB antenna) or modules that have an RF connector to an external physical antenna, how this works:- In the first case it's useless to certificate this modules becouse it's necessary to do again certifications on assembled board with antenna?- In second case it's necessary to do FCC?

author: ataradov
author_rank: Super Contributor
timestamp: March 17, 2016, 04:35:58 pm
content: Quote from: Yaro on March 17, 2016, 10:35:46 amIf you do a development board for anything wireless you have to be sure that if customer copies the board, they will be able to pass certification. So manufacturers will do at least FCC-prescan. And from prescan to getting a real certificate is just a small sum of money, so you might get it as well.Quote from: Yaro on March 17, 2016, 10:35:46 amIf you have only one intentional radiator in your device, then you can transfer module's FCC certification to your product. There is some specific text you need to put on a package.The module must have modular certification. You can't get another finished device, disassemble it, and put parts into your product. That will not work.Quote from: Yaro on March 17, 2016, 10:35:46 amThat's sketchy. Certification with external antennas specify directionality and gain of the antenna. Your design must use the same type and then you are in the clear. But I don't know how this works for PCB antennas.
How would a laptop's charging circuit react to being fed 5V instead of 20V? - Page 1
Forum section: electronics / projects

author: AnasMalas
author_rank: Regular Contributor
timestamp: June 06, 2021, 07:01:04 pm
content: Hello! I thought it would be better if I get the opinion of people who know a thing or two, specifically about how laptops, or just how devices in general would handle their charging input being sent a lower voltage.Specifics:I have a Lenovo Yoga 510-14ikb which uses a 4.0-1.7mm barrel jack to charge. The power adapter is rated for 20V 65W. I want to buy a USB C to 4017 barrel jack "decoy", which negotiates 20V from a suitable USB PD powersupply/charger and feeds it to the laptop. I will most probably be using it with a powerbank.This thing:https://web.archive.org/web/20210606161129/https://www.ebay.com/itm/382893782230Question:As USB PD chargers are designed to default to 5V output, it is bound to happen that the charger will give the laptop 5V. Maybe for a brief pulses, or that it will fail to negotiate the needed 20V. So, how would most laptops react to this? Would it damage the laptop somehow, or would the laptop possibly overload the charger? My intuition is that it will just not charge, but intuition can be sometimes costly

author: jmelson
author_rank: Super Contributor
timestamp: June 06, 2021, 07:06:29 pm
content: I made a rig to run a Dell laptop in a car. It was mostly just a car lighter plug to the 19 V laptop power connector.It would run in parallel with the 11.x V laptop battery for several hours, but the laptop battery would eventually run down and the computer would start getting battery alarms. With a 14 V to 19 V converter adaptor, it runs just like it was on the wall plug adapter.With 5 V, it will do nothing except run off the internal battery.Jon

author: rvalente
author_rank: Frequent Contributor
timestamp: June 06, 2021, 07:16:20 pm
content: Probably nothing, usually the 19V is reduced to 13V or so through a buck converter, to supply the battery charger and then other bucks to the 5V, 3V3, 1V8, 0V9 and so on..Attached a diagram for a modern computer, so you can understand the architecture, which is pretty similar.

author: AnasMalas
author_rank: Regular Contributor
timestamp: June 07, 2021, 05:57:17 am
content: Thank you both! These are exactly the answers I wanted, both the technical and the anecdotal.
How would you attach shield first (relocating passive sensor in to outside case) - Page 1
Forum section: electronics / projects

author: babysitter
author_rank: Frequent Contributor
timestamp: October 17, 2024, 09:14:33 am
content: Dear group,I'm about to relocate a passive internal sensor (dc-fed, slow, resistive) to a outside place. The device is handheld, battery-powered.The cable has a shield and shall be attached at device side, unattached at sensor side.I've located three possible attachment points, X1, X2, X3 and wonder which one i should try first w/ regard to ESD/EMI.Everybodys darling GND is not included, actually, for reasons.X1 is rather easy, positive battery, which looked at thru the AC glasses should be grounded due to bypass capacitors. Might be the most robust esd-wise as its going to the most massive power planes, but somewhat distant from sensor signal, impedance-wise.X2 is sensor positive supply, coming from a regulator, also bypassed. Closer to sensor network, impedance-wise, but less robust.X3 is sensor negative supply, not bypassed, but going thru a low side switch - I figure this as the worst rn.Ignore other possible issues of the cabling, like additional capacitance at the signal line and wiring resistance forming a RC lowpass.Any recommendations?BRBabysitter

author: Salitronic
author_rank: Contributor
timestamp: October 17, 2024, 10:18:46 pm
content: The way i see it:- X3 is definitely a no for ESD, ESD contact test on the mosfet drain will damage it, at least when it is powered off.- X1 is best for ESD but if you have digital and other switching circuitry on VCC you'll be radiating that out off the shield. Also if X1 is directly connected to the battery without any protection you need to consider the risk of overloading the battery.- X2 is probably a good compromise, though not ideal.
How would you model a Mini-Circuits MMIC amp (PSA-8A+) in MultiSim? - Page 1
Forum section: electronics / projects

author: abitofhelp
author_rank: Contributor
timestamp: December 31, 2024, 08:19:57 am
content: Hello,I am building an RF white noise generator and plan to use Mini-Circuit's PSA-8A+ MMIC amplifier. In order to verify my design in MultiSim, I used an LM324 opamp. Now, I would like to replace the opamp with the real component. Is there any way to model the PSA-8A+ MMIC amplifier so it can participate in simulations?Component: PSA-8A+Link:https://www.minicircuits.com/WebStore/dashboard.html?model=PSA-8A%2BThank you for your suggestions!Mike

author: IconicPCB
author_rank: Super Contributor
timestamp: December 31, 2024, 12:26:06 pm
content: Do you need to use the mini circuit part and why?
How would you power 4x separate isolated RS485 transceivers? - Page 1
Forum section: electronics / projects

author: jneudorf
author_rank: Newbie
timestamp: December 18, 2019, 07:20:51 pm
content: I am considering using 4x Recom RFMM-0505S DC-DC modules ($1.31 each at Mouser) for power, and Analog's ADUM1201ARZ-RL7 ($0.65 at LCSC) to get the signal across.I'd rather just make some isolated converter like inhttp://www.ti.com/lit/ug/tidu590/tidu590.pdfbut the Wurth 760390014 only has a single output and costs $1.25 on its own.Should I consider using Coiltronics Versa-Pac or Coil-Craft Hex-Path HPH1 series, or are there other options that might work? I can't find Asian sources that seem similar to these.The context is bi-directional DMX/RDM at 250kbps.

author: David Hess
author_rank: Super Contributor
timestamp: December 19, 2019, 01:10:56 am
content: I would use a pair of trifillar wound transformers in an inverter circuit. This only requires one simple driver.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 19, 2019, 02:23:21 am
content: Hex-Path is a good option, mind the isolation is only a hundred volts or whatever -- fine for signal purposes, but beware of ESD damaging it. (You could bridge grounds with a little MOV or TVS to control this.)If I needed more, or lower cost, I might consider planar transformers -- do it all in the PCB itself. This is a more advanced option though, as you're doing the transformer design yourself, and you don't have many protos to iterate on.Quote from: David Hess on December 19, 2019, 01:10:56 amAn interesting option would be to abuse some CMCs (data or data/power type), driven with a few logic gates or a gate driver, to make a simple chopper; FWB the secondaries and there you go. Put a bunch of primaries in parallel -- one for each channel -- not really a need for multifilar, the dual-line kind (which are usually bifilar) should be good enough. Downside is the lack of current limiting, which may have workarounds (e.g., use a motor-driver H-bridge chip, and use its internal current limiting, or supply it with a current limiter), and of course the cross-regulation is limited by leakage inductance.Tim

author: rvalente
author_rank: Frequent Contributor
timestamp: December 19, 2019, 09:40:11 am
content: This topic is very similar to yours,https://www.eevblog.com/forum/projects/isolated-5v-5-10ma-supply/msg2816550/#msg2816550
Howard Johnson notes on SI and scopes - Page 1
Forum section: electronics / projects

author: AlfBaz
author_rank: Super Contributor
timestamp: February 16, 2014, 01:41:52 am
content: Just found these 8 short notes by Dr Howard Johnson for lecroy.This may have been posted already but I couldn't find it with a quick searchhttp://teledynelecroy.com/support/techlib/signalintegrityfundamentals.aspx?capid=106&mid=528&smid=661The 8 articlesQuoteAs you can see it requires registrationI could zip them and attach (about 2M) just not sure on the ethics

author: oohal
author_rank: Newbie
timestamp: February 16, 2014, 06:21:03 am
content: Looks like you can get all of these off Johnson'swebsite. Incidentlybugmenotis pretty rad for getting around registration walls.

author: zapta
author_rank: Super Contributor
timestamp: February 16, 2014, 06:33:05 am
content: Quote from: AlfBaz on February 16, 2014, 01:41:52 amMailinator.com is your friend ;-)

author: codeboy2k
author_rank: Super Contributor
timestamp: February 16, 2014, 12:03:40 pm
content: 10minutemail.com

author: zapta
author_rank: Super Contributor
timestamp: February 17, 2014, 12:56:14 am
content: Quote from: codeboy2k on February 16, 2014, 12:03:40 pmBookmarked ;-)

author: dannyf
author_rank: Super Contributor
timestamp: February 17, 2014, 01:24:27 am
content: Wow. That Howard Johnson guy is not only good at building cheap motels, but also equally good at electronics.

author: AlfBaz
author_rank: Super Contributor
timestamp: February 17, 2014, 01:55:55 am
content: Quote from: oohal on February 16, 2014, 06:21:03 amNice, thanks
Howland Current sink minimum output current - Page 1
Forum section: electronics / projects

author: nitish111
author_rank: Contributor
timestamp: October 08, 2018, 05:37:31 pm
content: Hi,I am designing a voltage controlled current sink(schematic attached). The minimum current on the output fro the simulation is around 1.05 uA but the circuit I built has a minimum output current of 25uA. I need minimum output current to be less than 10uA. How do I bring output current down to 10 uA or less? All resistors are 0.1% tolerance.

author: duak
author_rank: Super Contributor
timestamp: October 08, 2018, 07:06:04 pm
content: It looks to me as if you are using a single supply of 40 V. The opamp will have a few hundred millivolt minimum output voltage that will cause an offset current to flow in the load. If you don't have a negative supply of a volt or two available, you could put a device with a threshold like back to back diodes in series with the output of the upper opamp to drop the offset voltage. You may also need to add a resistor after the diode to circuit common to absorb any leakage current. Note that this this could affect AC stability so there could be other changes needed such as a capacitor across the diodes.Cheers,

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 08, 2018, 07:26:00 pm
content: Definitely add a negative supply to your opamps. Doesn't need to be symmetrical. A small negative supply should be enough.It will still be hard to guarantee a "zero-volt" current of 1 µA or less, but you can get closer to it.

author: nitish111
author_rank: Contributor
timestamp: October 09, 2018, 01:23:12 pm
content: Thanks SiliconWizard and duak, I connected opamp to negative 3.3 V supply and biased input voltage to have minimum of around -0.1 V with resistor divider and it gives me around 2 uA which is perfect. Now the circuit has a small DAC offset which is not so bad.
How/where to enter into the market with an embedded team - Page 1
Forum section: electronics / projects

author: mrburnzie
author_rank: Regular Contributor
timestamp: October 22, 2020, 04:48:04 pm
content: Hi!It's quite hard to put the subject into a title...I have a team of engineers, that are focused on embedded. Hardware designers (PCB design, assembly), mechanic (case design, 3d printing) and embedded programmers. It is a team of 5 people.All of us have experience with large projects which were/are in production and we have worked together before. The team atmosfere is great.We don't have anything special when it comes to setup, only the basics (soldering iron, oscilloscope, development boards).My question is, as a small company in the embedded field, how should we approach the market? Go with a product and put it up for crowdfunding (which would probably fail) or go with getting clients to start working on developing products? I even thought about getting an investor for funding good equipment and then bringing in connections for clients rhat need development.What is the best approach?

author: Benta
author_rank: Super Contributor
timestamp: October 22, 2020, 06:05:28 pm
content: I know companies like yours, and it's always a chicken/egg situation getting started.You can either try to do a sales job to find a reasonable customer project, or you need to develop special skills yourself.Either way, you'll need a list of references of the work you've done, which is of course impossible when starting out.Ask yourself: do we have have skills in this team that stand out, and can we develop them further?eg, IoT, power, wireless, sensors, optics and so on. Think about areas where most "normal" customers don't have their own expertise, or the entry bar is too high to do it themselves.And a Hot Tip: seek the distributor FAEs as your allies. Some people have badmouthed them here as "useless", but they're excellent networkers. And if you have special skills, thay're in a very good position to connect you to potential customers, which is a win-win-win situation for all.Good luck.PS: I've had excellent results working with Serbian engineering consultants.

author: mrburnzie
author_rank: Regular Contributor
timestamp: October 22, 2020, 07:09:20 pm
content: Benta, thanks for your kind message.What is the best way to find clients? Social media marketing? I don't think larger clienrs hang out on that... LinkedIn could be a good shot, but I don't think it's focused enough.What do you recommend?

author: l0wside
author_rank: Regular Contributor
timestamp: October 23, 2020, 02:36:30 pm
content: You could try Upwork and the like and offer consulting/engineering services. Having some work samples surely will not hurt.I am unsure about your background. Either it is "we all just got fired together and want to make the most of the situation" or "fresh out of university, let´s just look what´s possible". The good thing about engineering services is that you do not need to invest large sums of money upfront. The bad thing is: you are completely dependent on your customer.
HP 04284-65007 'Interface Box' LCR test fixture, looking for internal photos. - Page 1
Forum section: electronics / projects

author: TERRA Operative
author_rank: Super Contributor
timestamp: June 15, 2024, 01:41:30 pm
content: As per the title, I am looking for some internal photos of a HP 04284-65007 'Interface Box' LCR test fixture.I am building my own and from the 4284A Operation Manual (pages 10-6 and 10-9) I have worked out the internal wiring, but I'd like to see just how HP actually constructed it.If anyone has one of these, can you take a peek inside and take some photos?Thanks!
HP 212A Pulse Generator 1954 all tube unit, test and teardown - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: May 13, 2022, 10:58:37 pm
content: my latest video release, wow what workman ship, all hand made, 25 tubesit also contain two Thyratron Tubeshttps://youtu.be/cKaCT2mK2XE

author: strawberry
author_rank: Super Contributor
timestamp: May 14, 2022, 07:17:27 am
content: must be called: scraping for metal HP212A

author: oz2cpu
author_rank: Frequent Contributor
timestamp: May 14, 2022, 09:23:24 am
content: or scrapping for tubes.. since the next owner told me he only wanted the tubes, and would trash the rest.if did not trash it, the next owner surely would, since i re-trade /swap all units after i am done playing with them,so it is the best of all, that i do it, this way we got all the cool details documented.And also : there exist NO old gear collectors in my contry. I tried many times,all i can get is 10-20 $ pr unit, and it takes 2-4 weeks for people to come pick it up.I am sorry but that is the way it is.

author: strawberry
author_rank: Super Contributor
timestamp: May 14, 2022, 11:41:06 am
content: rare to get with good visualsMr Carlson's lab on youtube would recap and change some carbon resistors and calibrate to factory specon mad ebay it could cost x10 with lost/broken dial..here any useful/esthetic test equipment containing gold/silver is scraped , almost nothing is left only some bottom grade trash they want for gold price

author: oz2cpu
author_rank: Frequent Contributor
timestamp: May 14, 2022, 04:27:34 pm
content: i think Paul is locared in the USA, love his channel by the way,it will cost big $ to ship that huge and that heawy equipment that far,money that no one would pay, at least no one ever contacted me, to ask for any equipment at whatever cost.Anyways the new owner is happy, he got his tubes, and we can be happymore cool design details was able to be discovered and documented, win win for all people.
HP 2800-2835 replacement diode - need help - Page 1
Forum section: electronics / projects

author: txescientist
author_rank: Regular Contributor
timestamp: March 24, 2018, 07:20:57 pm
content: Hi to all,I need a replacement diode for the schottky diode HP 2800-2835, but can't find any info about it. It is mentioned in Canberra Spectroscopy Amplifier Model 2012 user manual. Amplifier is used to amplify and shape pulses from ionizing radiation detectors - NaI and HPGe...Diodes are used in a way described in attachment. In short, they prevent scope input overload when measuring at 50mV/div AC range at DC bias voltage over 10V which is important for adjusting amplifier baseline re sorter. Can some modern diode be used for this? I guess many can, but without the original specification I don't know.Thank you for reading this post and hope someone can help me...Datasheet for the amplifier:https://www.google.rs/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0ahUKEwi49dmZ0oXaAhVHdCwKHdkNCngQFgg-MAM&url=https%3A%2F%2Fwiki.brown.edu%2Fconfluence%2Fdownload%2Fattachments%2F1164129%2F2022%2520Manual.pdf%3Fversion%3D1%26modificationDate%3D1438369064000%26api%3Dv2&usg=AOvVaw36nk3lS666Zu8G61fskXqG

author: rf+tech
author_rank: Frequent Contributor
timestamp: March 24, 2018, 08:31:02 pm
content: Hello txescientist,The HP part number in the schematic is a bit misleading. It appears to be two different part numbers munged together.The Schottky diodes specified were likely to be either HP 5082-2800 or HP 5082-2835.Given the note in your attachment:Quoteimplies that the HP 5082-2835 is unsuitable, due to its breakdown voltage rating of less than 10 Volts.A pair of 1N5711 would be suitable. See attached HP 5082-2800 datasheet for further details.If the original part is SOT-23-3, HSMS-2800 (1N5711) is available as two series-connected diodes, see available configurations in the HSMS-28XX-series datasheet attached below.RF+ Tech

author: txescientist
author_rank: Regular Contributor
timestamp: March 24, 2018, 09:05:06 pm
content: Hi rf+tech,Thank you very much! Did cross my mind that that was a range of diodes just like 1N4001-1N4007, but failed to find a datasheet. Now I can make the adapter from the manual to measure and set baseline re sorter.
HP 302A Wave Analyzer 1959 first transistor instrument teardown - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: May 10, 2022, 08:47:34 am
content: https://youtu.be/3X_APCzriLoThe first all transistor instrument, more info here.https://hpmemoryproject.org/news/300a/hp300a_page_00.htmWOW this HP unit is actually designed before this Radio meter all tube versionhttps://youtu.be/-fPKqbIIHrsthe HP unit uses 1/100 the power consumptionand is also much less weightboth works, and do more or less the same, analyze for harmonics
HP 3325a 50 bnc termination - Page 1
Forum section: electronics / projects

author: valvedoctor
author_rank: Contributor
timestamp: July 05, 2016, 05:25:03 pm
content: Hi all,Should the termination for this unit be 50 ohm feedthrough or not?What is the implications of using feedthrough vs 50 ohm to common-type terminator?Sent from my iPhone using Tapatalk

author: danadak
author_rank: Super Contributor
timestamp: July 05, 2016, 09:04:33 pm
content: Maybe I do not understand the question but the main output is 50 ohms, so atclient end you should also be terminated in 50 ohms.Regards, Dana.

author: valvedoctor
author_rank: Contributor
timestamp: July 05, 2016, 09:09:05 pm
content: You can get a feed through 50 ohms which is a series resistor through , or you can get a 50 ohm termination that goes to the shield of the cable, as in parallel.I'm wondering the differences.Sent from my iPhone using Tapatalk

author: edpalmer42
author_rank: Super Contributor
timestamp: July 05, 2016, 09:25:52 pm
content: Feedthrough vs. regular termination has no relationship to any particular generator or receiver/meter/analyzer. It's just two different ways of accomplishing a proper termination.If your receiver/meter/analyzer includes an internal termination, it's best to use that. If not, or if the internal termination is bad, you can use a feedthrough termination and leave your analyzer on its high impedance setting. Note that 75 ohm isNOThigh impedance.If the frequency is relatively low, i.e. less than maybe 10 MHz, you could install a BNC-T adapter and add a regular 50 ohm termination to the third port. Don't try this at high frequencies! You'll get lots of reflections and strange results.A regular terminator would be used to terminate unused ports on something like a splitter or amp where an unterminated output port would upset the performance of the other ports. It could also be used to terminate an unused input to prevent noise pickup.Ed

author: edpalmer42
author_rank: Super Contributor
timestamp: July 06, 2016, 12:27:00 am
content: Quote from: valvedoctor on July 05, 2016, 10:18:31 pmThe only difference in loading is that the feedthrough terminator has 50 ohms to ground plus whatever is in the 'next' unit in the chain, probably 600 ohms in your case. This gives a total of about 46 ohms. Not significantly different from 50. Resistive vs. capacitive isn't really an issue at audio frequencies and low impedances.But at audio frequencies at these low impedances, you don't need to worry about termination at all. If you want to connect the 50 ohm generator to the 600 ohm or higher impedance of an amplifier, go right ahead, nothing will break. Just remember that if the generator isn't terminated in it's preferred impedance, the output voltage will be different than you expect. For example, 0 dBm into 50 ohms is ~0.22 Vrms. Take off the termination and the voltage will double. Add something else in parallel with a 50 ohm termination and the voltage will drop. Some generators have a Vemf output scale which shows the actual RMS output which then goes through the output impedance and the load impedance. If the 3325A has that option it might be convenient for you.Ed
HP 3478a, find date by serial? - Page 1
Forum section: electronics / projects

author: ALearningLad
author_rank: Contributor
timestamp: January 09, 2022, 03:07:18 am
content: Just got a 3478a but I am wondering about production date. How do you find that from the serial number? Sorry if it's a stupid question...

author: Tj138waterboy
author_rank: Regular Contributor
timestamp: January 10, 2022, 12:59:51 am
content: Pages 76-86 of the service manual refer to serial number and part replacements and updates may be able to cross reference serial number by year with some work.

author: ALearningLad
author_rank: Contributor
timestamp: January 10, 2022, 01:40:57 am
content: I must have missed that, time for another read of the service manual! Thank you!

author: edpalmer42
author_rank: Super Contributor
timestamp: January 10, 2022, 06:53:07 pm
content: HP Serial numbers include the date code of the design version. i.e. if the serial number was 2335A1224, the 23 tells you that the unit includes all design updates up to 1960 + 23 = 1983. Why 1960? Because that's when they started using this system.The 35 means week 35 of that year. This doesn't directly relate to the production date, but it gets you close. To go further, look for date codes on things like capacitors, ICs, etc.Ed
HP 3478A Hybrid module die photos. - Page 1
Forum section: electronics / projects

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 20, 2020, 02:44:36 pm
content: So I just fixed my HP3278A multimeter with a new hybrid module and thought I'd crack open the faulty one for a sneaky peek inside.I thought someone else might find this passably interesting, so here are the photos, you can see on the top center-right the melted bond wires (one trace missing from when I lifted the lid) that melted, rendering the AC ranges unuseable.

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 20, 2020, 02:47:51 pm
content: Closeup of all the dies

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 20, 2020, 02:48:22 pm
content: Single Die #1

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 20, 2020, 02:50:17 pm
content: Single Die #2

author: TERRA Operative
author_rank: Super Contributor
timestamp: October 20, 2020, 02:52:45 pm
content: Single Die #3
Hp 3562a programming - Page 1
Forum section: electronics / projects

author: cncjerry
author_rank: Unknown
timestamp: November 21, 2020, 06:59:54 am
content: I have written thousands of lines of GPIB code for many devices from HP, Tek, R&S, etc. but the Hp 3562a is kicking my butt. I usually rough the code out in Visual Studio using Visual Basic or Visual C# depending if I have base level code in either language. I'm using the Agilent USB GPIB adapter and VISA comm software as the interface. All this works fine with my other units and codes.I can see the unit on the GPIB buss in both my code and either the NI or Keysight interactive command software. When I send a command, the unit lights the appropriate listen/talk led but doesn't reply or act upon my commands. I was thinking termination character so I tried all the usual suspects of CR, NL, CRNL or NLCR. Tracing the GPIB commands, I can see them go over but no reply back. After sending the command, I issue the receive command and all I get is a timeout. I also have used the NI and Keysight interactive codes and they timeout as well. The 3562 can be in addressed or system controller mode and I'be tried both,In VB, I am writing strings with the WriteString command with and without the addition of the termination character, still no luck. The addresses are right and I've read through all the examples in both the programming doc as well as some of the LabView Examples. I was thinking of trying Labview next but haven't played with it in so long I thought I would try here first.If anyone has some ideas, or possibly some python code that works, that would be helpful. I'm trying to get a plot dumps as I am doing some phase noise measurements with a quadrature mixed signal in front of it but I would settle for any indication that it accepted my commands right now.ThanksJerryedit: Great memory there dad! After I wrote this thread I started thinking about it. I was sitting in my family room, looked at my MS Surface and it all came back to me because I had the 3562 in that room getting ready to fix an amplifier that had distortion in one channel. I not only wrote this code before, I had an entire plotting system to calculate crossover frequencies, etc with cursors, the whole shebang. So I brought the code to my office and it isn't working either. There is an issue in the version of VISA I am running so I'll have to figure that out. thanks anywayedit2: turned out to be the USB extension cable I was using. It was only about 1meter long but I guess something is wrong with it. Go figure.
HP 41-CX with weird keyboard - Page 1
Forum section: electronics / projects

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 06, 2016, 11:46:34 pm
content: Anyone seen an HP-41 like this? It is up on Ebay at the moment. Non working. Is it an actual HP product, or is it a kind of impressive repair of a failed keyboard by someone? Or maybe even a flexible overlay?

author: dacman
author_rank: Frequent Contributor
timestamp: April 07, 2016, 12:54:25 am
content: It looks like an HP-41 that has an HP82200A keyboard protector touchpad installed.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 07, 2016, 03:17:45 am
content: Never knew there was such a thing. I've had a 41C and two 41CX but hadn't seen that before.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: April 07, 2016, 04:13:00 am
content: dacman +1Here is a link:http://www.thecalculatorstore.com/Touchpad-for-HP41Regards,Jay_Diddy_B

author: linux-works
author_rank: Super Contributor
timestamp: April 07, 2016, 04:18:24 am
content: wow, never heard of that or saw one before.I have a 41c of some kind that was gifted to me some 20+ yrs ago. back when USENET was still for humans, we had a ba.market.computers usenet group that was great for local swapmeet stuff (long before there was an ebay). some guy put his up for free in non-working condition and I met him, we chatted and I went home with the calc and was curious to see what was wrong.I ended up soldering wire wrap wires to all the contacts, one by one, on the display to the main board. that's what was wrong and I brute-force fixed it that way. probably ruined some collectable value but its perfect from the outside and perfectly reliable, now, from the inside.came with card reader, bunch of cards, bunch of app packs and boxes. really nice gift but the guy was not using it and didn't care to put repair time into it.I have it, its nice to use, but it sits in its box more than it will ever get used. maybe I should put mine up for sale, too.I kind of like my hp25 better. not sure why, but I do.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 07, 2016, 03:03:18 pm
content: Thanks for the link. One of my 41s was an OEM product for someone who used it as a process controller. Doesn't have the standard keys so I have to use the functions by memory. Since I use it a lot less now than I did 30 years ago the memory isn't too reliable, and something like this would be really useful. But at 50 Euros I think I'll just use one of the other ones, even though the exchange rate is pretty good right now.
HP 410C Electronic Voltmeter 1962-1968 test repair teardown (NEON-LDR CHOPPER) - Page 1
Forum section: electronics / projects

author: oz2cpu
author_rank: Frequent Contributor
timestamp: May 11, 2022, 01:01:16 pm
content: i just love HP gear, always pleasure to see how well it is designed.here is my latest video releasechopper amplifier, optical NEON-LDR switcher, amp designed with tubes and transistors, really cute micro tube-diode inside the AC probe, full deep teardownhttps://youtu.be/yjs8-LcDhgM
HP-41800A clone ideas? - Page 1
Forum section: electronics / projects

author: WB8PFZ
author_rank: Regular Contributor
timestamp: March 15, 2020, 02:49:36 pm
content: My HP spectrum analyzer needs an active probe similar to the HP41800. Lots of money for something not used very often. Does any one have any ideas to a comparable circuit. I am not doing lab stuff just probing around radio circuits. I was thinking a few MMICs. Thanks Mike

author: SuzyC
author_rank: Frequent Contributor
timestamp: March 16, 2020, 05:53:44 pm
content: Just use a n-chan enhancement mode JFET common-drain follower to make a very high impedance low cap(<5pf) active probe tip that you can make using a tiny piece of PCB copper laminate to attach to the end of a scope probe. Only limit: low-voltage circuits, otherwise a coupling capacitor(5pf)/22-meg input resistor G-S would be needed.You can supply +12 V to the JFET source and set the JFET drain resistor to 50 to 500 ohms to -12V, maybe OC or 22-Meg gate to source pull-down. The gate to source resistor is not needed once the gate is connected to the circuit point of interest.