EEVblog #651 - Mailbag - Page 1
Forum section: electronics / general

author: ElektronikLabor
author_rank: Regular Contributor
timestamp: August 12, 2014, 06:44:21 am
content: Thank You for the teardown of my stuff, Dave.I'm that guy from NorderstedtYou asked where the funky "recorder" with the chopper amp comes from: It was used for many years at theTechnical University of Hamburg.

author: Kjetil
author_rank: Regular Contributor
timestamp: August 12, 2014, 06:46:35 am
content: Cool stuff again. A video on powering VFD's would be nice, got a few of them that I haven't got working.You need a new hat now too, a crocodile dundee one, just with IC's instead of crocodile teeth

author: Greg323i
author_rank: Contributor
timestamp: August 12, 2014, 09:57:44 am
content: Gossen Metrawatt was formally BBC Goerz Metrawatt. I'm not certain of the story/buyout/what have you, but I own a BBC Goerz Metrawatt DMM from the mid '80's (I was working in a wholesale electronics supplier and it was old stock, so got a deal on it). I contacted Gossen Metrawatt to see if they had a manual for the meter and they supplied me with a PDF copy, in German. It was all they had. Nice old school meter.

author: JonnyBoats
author_rank: Regular Contributor
timestamp: August 12, 2014, 10:23:21 am
content: Dave,When are you going to open a can of beer with that knife?In fact how about a teardown Tuesday where you literally rip apart some things with that knife; I bet the Energizer bunny wouldn't stand a chance ;-)

author: slr4875
author_rank: Newbie
timestamp: August 12, 2014, 11:58:34 am
content: The Eurotherm device looks like a kiln controller.Noritake Itron make very nice VFDs. Some are HD44780 compatible. Their products are a bit pricey but they usually have some items on special.

author: m100
author_rank: Regular Contributor
timestamp: August 12, 2014, 12:03:22 pm
content: 'BBC' in this case being Brown Boveri & Cie of Switzerland, who merged with Asea of Sweden in the late 80's to become ABB

author: rs20
author_rank: Super Contributor
timestamp: August 12, 2014, 12:05:51 pm
content: Regarding those multimeter-style switches -- the one with the big shaft coming from the front panel and going through a couple of switch units on those verticals boards -- what search terms should I be using to find those switch units on digikey/farnell etc for use in my own projects?

author: xDR1TeK
author_rank: Contributor
timestamp: August 12, 2014, 12:19:29 pm
content: Must have knife!!!! Want knife now!!! Me go tinker!!!

author: dentaku
author_rank: Frequent Contributor
timestamp: August 12, 2014, 12:26:01 pm
content: After you did your video about enclosures and how you wanted to mount the display for your power supply project I thought you should do a video on driving LCD/LED/VFD. They're incredibly easy to salvage from old electronics but often rather intimidation for beginners because you don't want to kill them by hooking them up incorrectly.A video on driving/controlling/multiplexing displays would be nice too.By the way, did you ever hook up one of Fran's Nixie tubes?

author: max_torque
author_rank: Super Contributor
timestamp: August 12, 2014, 12:47:50 pm
content: Can we have an EEV sweepstake for how many "mailbags" it takes before Dave cuts one of his fingers off with that massive knife?I'm going with 5..... ;-)

author: nathanpc
author_rank: Unknown
timestamp: August 12, 2014, 02:10:37 pm
content: It would be very interesting to see a video on salvaging and powering VFD displays.

author: synapsis
author_rank: Regular Contributor
timestamp: August 12, 2014, 02:17:04 pm
content: Haven't seen the whole video yet (Dave posts too late for some of us working Yanks!), but I do regularly work with Eurotherm units in industrial automation.That unit is ancient obviously, and the unit series I work with most of the time is the 2400s (2404, 2408, 2416), but there are similarities.Eurotherm still builds their temperature controllers the same way. There's a display board in the front (LED these days) with various boards stacked out the back. There's usually a power board (24VDC or 120/220VAC), and an analog board (for thermocouples, the ones I use are usually two channel type K.) Eurotherm sells option boards that plug into the unit. The options can be things like 0-10V/4-20mA analog retransmit of the process variable (temperature), relays that trigger on setpoints, or communication modules like RS422/485. The 2400 series has a chassis that you mount into a square hole in the panel, with the same type of contacts Dave had on his model. Then the unit has two tabs on the front that let you slide the whole inside of the controller out without removing the panel. The back of the chassis has screw terminals for connection to the rest of the system.The menu system has a *lot* of settings on my units, with different security levels. Level 1 is for setpoints and possibly alarms. Level 2 is for more complicated things like PID parameters, deadbands, and option configuration.I might be able to send Dave a 2404 (we have a box of parts somewhere around here) if he's interested. If anything he could use it to control his lab air conditioning.

author: Rory
author_rank: Frequent Contributor
timestamp: August 12, 2014, 03:19:14 pm
content: Is solder smoke easy to get off the microscope lens without damaging the ARAG coating? Or does it have a neutral density filter in front?

author: sergey
author_rank: Regular Contributor
timestamp: August 12, 2014, 03:35:35 pm
content: Just in case Sergey (if i type it correctreading this thread, i had the similar question couple of months ago, and if you search for "NEC LD8121"here on the forum you'll find a discussion how to power VFD up and know it's pinout.Hope it helps

author: Wytnucls
author_rank: Super Contributor
timestamp: August 12, 2014, 04:04:04 pm
content: Quote from: max_torque on August 12, 2014, 12:47:50 pmI put my money on the bare toes, when that scimitar slides of the bench....

author: SeanB
author_rank: Super Contributor
timestamp: August 12, 2014, 05:01:28 pm
content: Like I said, the scanner was dropped by Ungaas, and she no work now. Still boots up to MSDOS though, which was interesting to say that it still would boot when I applied 5v to it. Of course with the tiny keyboard with only a numerical pad i was rather limited, likely it would respond to a serial link as well, or likely there is a regular XT keyboard controller interface inside there.

author: Tek_TDS220
author_rank: Regular Contributor
timestamp: August 12, 2014, 10:04:28 pm
content: Upside-down oscilloscope on the shelf - the electrons will fall out!!!I've purchased several of the 1/4 DIN PID controllers, but not from this particular manufacturer. They have a lengthy list of options, which are encoded in the serial number. They are built from parts when you purchase them. They are bullet-proof, running 24/7 for 20 years. I've never seen a failure when they are properly hooked up. And yes, very difficult to program even if you have the manual.

author: Smokey
author_rank: Super Contributor
timestamp: August 12, 2014, 11:44:59 pm
content: What PCB autorouters existed in 1985?

author: coppice
author_rank: Super Contributor
timestamp: August 13, 2014, 03:24:30 am
content: Quote from: Smokey on August 12, 2014, 11:44:59 pmAh, good old 1985, when we used to watch our PCBs autorouting on 4k resolution screens. Its only 29 years later, and we are finally getting our 4k screens back. :-)None of the currently popular autorouters were around in 1985, but there were several good ones back then. I just can't remember their names. That was the period when hand layout of ICs was becoming totally impractical, and there was intense research into more effective algorithms for autorouting. What was developed for ICs spilled over into PCBs, so PCB autorouting was moving forward pretty well then. A huge number of PCBs were still being laid out with black tape on mylar film, though.I first autorouted a PCB in 1977. The equipment I used was about $300k, and the software was some horrendous price too.

author: motocoder
author_rank: Unknown
timestamp: August 13, 2014, 03:18:40 pm
content: Quote from: Kjetil on August 12, 2014, 06:46:35 amWhile a video on VFDs would be nice, there are a lot of good resources about them on the Internet. See the Wikipedia page on the topic, particularly the External links at the bottom of the page. There is even a link to a simple test circuit there (uses 9V batteries and a 1.5V AA battery in series to generate the necessary voltages and filament current.Wikipedia Page:http://en.wikipedia.org/wiki/Vacuum_fluorescent_displaySimple VFD test circuit:http://www.tubeclockdb.com/vfd-tubes/100-simple-vfd-tester.htmlGreat guide to VFD operation from Noritake:http://www.noritake-elec.com/vfd_operation.html

author: edpalmer42
author_rank: Super Contributor
timestamp: August 13, 2014, 07:06:43 pm
content: Dave,I don't know what you're using for an anti-static wrist strap, but the two wrist straps in that medical device look like they have snap fasteners for the cables. If the snaps are the right size, you've got two of the best quality wrist straps around.Ed

author: PA0PBZ
author_rank: Super Contributor
timestamp: August 13, 2014, 08:15:16 pm
content: Quote from: Smokey on August 12, 2014, 11:44:59 pmPC-based:Altium (Protel)P-CADORCAD (maybe not '85)And probably a lot I forgot..

author: IO390
author_rank: Regular Contributor
timestamp: August 13, 2014, 08:45:17 pm
content: Funny to see Eurotherm there. They distribute some of my dad's stuff.

author: Don Hills
author_rank: Regular Contributor
timestamp: August 14, 2014, 01:14:36 am
content: Quote from: edpalmer42 on August 13, 2014, 07:06:43 pmEr... no, for at least two reasons.First, they're metallic. Think short circuit.Second, they are unlikely to have the required resistor in circuit between the bracelet and the strap.

author: ivaylo
author_rank: Frequent Contributor
timestamp: August 14, 2014, 02:13:34 am
content: Intermec used to make the cutest industrial portable computers running MSDOS and even Windows. My first job in the states in the late 90s was in a paper mill where the fork lifts were equiped with those with a bar code scanner able to read like 20m away, (not kidding) and all connected via radio across the multi acre factory floor. Hadn't seen wifi at the time I thought that's the coolest thing ever.

author: edpalmer42
author_rank: Super Contributor
timestamp: August 14, 2014, 02:57:52 am
content: Quote from: Don Hills on August 14, 2014, 01:14:36 amThere are many metallic wrist straps. Some have insulating covers over the outside, some don't. If you're using it on unpowered equipment it doesn't matter, but you're right that it wouldn't be appropriate on live equipment. I guess it's possible that there's a clear insulating film on the ones in the video, but it doesn't seem likely.AFAIK, the required resistor is always in the cord, never the wrist strap. My thought was to use those wrist straps with the cord for a regular anti-static strap. That's why I made the comment about the snap. Guess I phrased it poorly.Ed

author: German_EE
author_rank: Super Contributor
timestamp: August 15, 2014, 05:25:21 pm
content: All agreed.I had a workshop job once where we were all issued with company watches, these had a metal wristband and the usual circular connector for the anti-static cord. The 1M resistor is ALWAYS in the cord, well, sometimes in the connector for the cord but you get the idea. This is because some equipment has attachment points on the chassis for a wrist strap.

author: nitro2k01
author_rank: Frequent Contributor
timestamp: August 16, 2014, 04:38:39 am
content: Quote from: Tek_TDS220 on August 12, 2014, 10:04:28 pmNo, he's in Australia, remember. That's actually his only 'scope with all its electrons intact.

author: coppice
author_rank: Super Contributor
timestamp: August 16, 2014, 07:43:23 am
content: Quote from: PA0PBZ on August 13, 2014, 08:15:16 pmThose packages may have been available in 1985, but did any of them autoroute in 1985? I know ORCAD only autorouted much later. I'm not sure about the others, but their early versions were intended to be cheap rather than highly functional.

author: boz
author_rank: Regular Contributor
timestamp: August 21, 2014, 04:50:04 am
content: The scanner is very close in function to my open source project,http://hackaday.io/project/1915If anyone is keen to see how one of these type scanners can be made for sub $100 in 2014 check it out (Warning the project is still work in progress)The V25 is the microcontroller version of the intel 80186 by NEC had some ROM and RAM and peripheral funcs (I cant remember) its only saving grace was it could run DOS, a bit power hungry as I remember surprised to find it in a handheld.