EEVBlog #930 - Mailbag - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: October 04, 2016, 02:06:07 am
content: More MailbagSPOILERS:Dave's first multimeter hack!Sinclair PDM35 MultimeterRussian analog multimeterCanyse 801 data loggerhttp://electronics-development.eu/Kickstarter Masso CNC Controllerhttps://www.kickstarter.com/projects/hindtechnology/masso-the-all-in-one-cnc-controllerhttp://www.hindtechnology.com/Lumintop Prince 1000 lumens flashlight torchhttp://amzn.to/2dmWXTlLumintop micro USB rechargeable 18650 cell teardownhttp://amzn.to/2dFCjsQCanon Ion Still Video Camera and the VF-50 2" floppy disk

author: n3vti
author_rank: Contributor
timestamp: October 04, 2016, 02:37:49 am
content: Sagan is so adorable.I have a few extra old RadioShack Multimeters, maybe Dave wouldn't mind a teardown for a future mailbag? Today just so happens to be my birthday and I really want to get rid of most of these meters so I can get the BM235.Oh, speaking of RS, apparently they're bringing the Tandy name back, in the form of wireless keyboards and mice. I'll post a picture in General Chat.

author: psidragon
author_rank: Newbie
timestamp: October 04, 2016, 03:34:47 am
content: So there are 208 pins on that package for the CNC controller, if that helps with the identification. What does the crystal package say? I couldn't get it off the video.

author: Vgkid
author_rank: Super Contributor
timestamp: October 04, 2016, 06:13:01 am
content: That was a nice mailbag.Never thought about multimeters not being fused.

author: Chipguy
author_rank: Unknown
timestamp: October 04, 2016, 06:46:59 am
content: The housing of that data logger seems to be from the german manufacturer Bopla:https://www.bopla.de/de/gehaeusetechnik/product/bos-streamline.htmlThe stand though is definetly from german manufacturer OKW:https://www.okw.com/de/Datec-Mobil-Box/A9250909.htmCheers

author: GUMY
author_rank: Newbie
timestamp: October 04, 2016, 07:01:26 am
content: Chipguy, You are absolutely right.

author: lemming
author_rank: Contributor
timestamp: October 04, 2016, 07:45:53 am
content: Quote from: psidragon on October 04, 2016, 03:34:47 amAppears to be 12MHz, I had a quick look on DigiKey and there were some 208 pin Renesas parts, but the location of the two crystals didn't match.It also appears there's a DAC for the VGA in the lower left corner, and a 64Mbit DRAM to the upper left of the main IC.

author: bktemp
author_rank: Super Contributor
timestamp: October 04, 2016, 08:34:11 am
content: My guess would be a Renesas or Freescale (NXP) controller. Maybe MAC57Dxxx?http://www.nxp.com/products/microcontrollers-and-processors/arm-processors/mac57dxxx/ultra-reliable-multi-core-arm-based-mcu-for-clusters-and-display-management:MAC57D5xxThey have a buildin videocontroller + GPU, SDRAM controller, stepper motor controllers and QFP208 package.

author: G7PSK
author_rank: Super Contributor
timestamp: October 04, 2016, 08:36:14 am
content: I had a sinclair multi-meter in the early 1980's absolute piece of crap. I dont know how many models they made but the one I had had a frequency range as well which is why I got it. It blew up when I tried to check the frequency of a genset. When I took it apart the case was a re-purposed calculator shell complete with all the holes for the buttons under a sticky cover. After that experience (the meter was in my hand) I never got another digital meter until a few years ago when I started watching the EEVblog up to then I stuck with AVO meters for voltage etc and and tachometers to measure the rpm of gen sets.

author: ckambiselis
author_rank: Regular Contributor
timestamp: October 04, 2016, 10:12:18 am
content: About the Lumentop USB rechargeable battery, they probably made it fit by removing/shortening the typical end cap spring from the flashlight.

author: max_torque
author_rank: Super Contributor
timestamp: October 04, 2016, 12:02:21 pm
content: I rekon Daves got about 2 years till Sagan makes him obsolete........... (then we can do a retro Teardown on him)

author: f4eru
author_rank: Super Contributor
timestamp: October 04, 2016, 05:17:16 pm
content: Concerning the CNC controller, meh....- optoisolated output : points to people not doing right the EMC/ground routing on motor controllers. You really don't need optos if you do your ground routing correctly. You. don't. need. isolation.- no power components ? you really must wire each power stage wire for wire on screw posts ? meh. That's really mean design- ground off chip ? no thanks. incompatible karma.

author: Jeff_Birt
author_rank: Regular Contributor
timestamp: October 04, 2016, 05:26:05 pm
content: Quote from: f4eru on October 04, 2016, 05:17:16 pmYou don't 'have' to isolate I/O but it saves you a lot of grief and blowing up your controls when things go wrong. want your 5V (or 3.3V) logic circuits directly connected to your 48V or 80V motor drives? Go for it.

author: nctnico
author_rank: Super Contributor
timestamp: October 04, 2016, 06:12:46 pm
content: In many cases the optocouplers are connected to the same ground so they don't isolate anything. Series resistors and zeners are just as good for keeping nasty stuff out of logic circuits and you can't wreck the LEDs in the optocouplers.

author: Jeff_Birt
author_rank: Regular Contributor
timestamp: October 04, 2016, 06:18:02 pm
content: ???If all of the control sides of the optos are share a common ground that is just fine, as well if all the outside world optos share a common ground that is fine (as far as the control is concerned.) If both sides of the optos share a common ground that is far less ideal.I suppose you think the guys who came up with Ethernet got it all wrong by transformer coupling both ends of the connection?If you had ever worked in a factory environment with sources of interference everywhere, or if you realize that beginners are going to be wiring up these DIY CNC products, you would not doubt the value if isolation.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 04, 2016, 06:44:07 pm
content: Having opto-couplers in a CNC control is a good idea. You may not need it with all inputs / output - especially something like switches are easier without. But there might still be the option to use a bridge instead. It looks like motor control is via RS232 or similar - makes some sense, but I don't know if this is a common standard. At least wiring is not that bad. However normal RS232 would not include isolation.

author: NottheDan
author_rank: Frequent Contributor
timestamp: October 04, 2016, 06:50:29 pm
content: Quote from: G7PSK on October 04, 2016, 08:36:14 amAyup. Look closely at the model in the video. Calculator shell with a custom face plate. I guess in your model they found a way on saving even more on the face plate.

author: nctnico
author_rank: Super Contributor
timestamp: October 04, 2016, 09:20:48 pm
content: Quote from: Jeff_Birt on October 04, 2016, 06:18:02 pmAnd yet that is what you see on some less clever designs. After all: there has to be some power source to drive current through the LEDs and it does take some thinking that this power source has to be isolated from the rest in order to make a difference.

author: reinhardz
author_rank: Contributor
timestamp: October 04, 2016, 10:19:30 pm
content: Hi DaveThanks a lot for your always interesting episodes. It would be very nice if you made a scan of the schematic of Sinclair PDM 35 multimeter. Many thanks in advance.Best regardsreinhardz

author: EEVblog
author_rank: Unknown
timestamp: October 05, 2016, 01:04:53 am
content: Quote from: max_torque on October 04, 2016, 12:02:21 pmI hope so, retirement sound good to me.

author: meeko
author_rank: Contributor
timestamp: October 05, 2016, 02:32:32 am
content: The school my Dad taught at had a Canon Xapshot, which was a similar still video camera, using the same video floppy disks, but only did composite video. I guess it was the predecessor of the Ion?They used it with a digitizer (Digiview, or something like that?) that connected to the parallel port of a Commodore Amiga. The digitizer was intended to be used with a B&W security camera, doing a 3 pass capture through red, green & blue filters. Dad's school used the Xapshot, though, and an electronic colour splitter to separate the red, green & blue channels.It was pretty neat for the day, but really crusty compared to modern digital cameras. It would have been at most 640x400, probably only 320x200. I think it might have used the Amiga's HAM mode, though, to (kind of) do 4096 colours.

author: gnavigator1007
author_rank: Unknown
timestamp: October 05, 2016, 05:58:39 am
content: I'm wondering if the note for the CNC controller password meant that the password is literally the word "blank". Seems suspicious that they underlined it.

author: Fungus
author_rank: Super Contributor
timestamp: October 05, 2016, 01:10:26 pm
content: I think I've still got a roll of waxy 'electronics' string somewhere.

author: Fungus
author_rank: Super Contributor
timestamp: October 05, 2016, 01:27:09 pm
content: https://en.wikipedia.org/wiki/Video_FloppyA Video Floppy can store 25 frames of interlaced PAL or NTSC video, 50 frames of non-interlaced.I've never actually heard of them before.

author: SeanB
author_rank: Super Contributor
timestamp: October 05, 2016, 05:29:48 pm
content: Quote from: Fungus on October 05, 2016, 01:10:26 pmI use it every so often, it is great for sewing heavy material. Don't remember how much I used in wiring looms though, it must have been enough that I have 2 spools of white waxed and one spool of an unwaxed brown nylon, plus a good assortment of sailmakers needles. Even have a few sticks of sealing wax around for the unwaxed ones where you needed to make sure it never came undone from the board or pannel.

author: MobileWill
author_rank: Regular Contributor
timestamp: October 05, 2016, 07:55:23 pm
content: The CNC controller IC reminds me of the STM32F429 in probably the 208 package, but not sure about the corner markings. I will have to check if STM32 uses those.

author: lemming
author_rank: Contributor
timestamp: October 06, 2016, 05:53:56 am
content: Quote from: MobileWill on October 05, 2016, 07:55:23 pmHaving had a look at the datasheet the location of the two crystals matches up nicely with the OSC_IN and RTC_REF pins on the IC.

author: MobileWill
author_rank: Regular Contributor
timestamp: October 06, 2016, 05:59:40 am
content: Quote from: lemming on October 06, 2016, 05:53:56 amI just checked and my stm32f429 only has two dimples. But it is only 144pin.Sent from my SAMSUNG-SM-N920A using Tapatalk

author: strangersound
author_rank: Regular Contributor
timestamp: October 10, 2016, 09:04:01 pm
content: The Russian multimeter is a beauty. I was not expecting some quality point to point wiring when he opened it. The Sinclair, not so much.Dave did make me feel better about my antiquated multimeter since he was raving about his first being an RS and gave him years of service. Mine is a Radio Shack (Micronta) 22-211A. I'm guessing I've had it since around '94/95, so it's served me well since I've never had an issue with it. It's always been for low V/A use, so I' guessing that's probably helped. It was a one of the nicer meters RS had back in the day.

author: kj5cn
author_rank: Contributor
timestamp: October 11, 2016, 01:55:52 am
content: That Russian Multimeter is C-20 - very popular and ubiquitous model in the USSR in the 60's-70's. I got one as a teenager and had it for something like 20-years - never failed me even with all the abuse that a stupid kid could impart on it.Too bad Dave failed to open the battery compartment - the battery is a unique 4.5V dry cell with flat leads, which were very conveniently located for one's tongue to fit in for voltage measurementPeter.

author: NottheDan
author_rank: Frequent Contributor
timestamp: October 12, 2016, 08:02:38 pm
content: Quote from: kj5cn on October 11, 2016, 01:55:52 amUnique? Well, they aren't all that common anymore but when I was a kid they were ubiquitous.