Just wanted to share, scored a working 2 digit working HeathKit DMM Nixie style! - Page 1
Forum section: electronics / testgear

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: September 22, 2015, 12:45:57 am
content: So apparently this was one of the first DMMs produced IM-1212 the IM-1202 came first, and I think another higher end kit was produced congruently. So this thing is one of the first of the first DMM's produced and its serial is 508!!Ive had a look at the insides and the manual its fully calibratable with trimmers, and only about 20mV off and .20 millamps. I mean this thing isnt really all that usefull.... I traded it for an ExTech ex430 which is I calibrated first for the guy, He really just wanted a decent meter for mains and car stuff, the ExTech was a backup to my Klien MM2000 and I have some Uni-Ts for electronics.What do you guys think, this thing is pretty neat huh? I partially got it to go along with the 200 in one kit I bought for my my 1.5 year old daughter, Im hoping by three shell be able to start understanding some basics and when the time comes this is about as simple of a circuit as it gets for a DMM.Im just wondering if anyone acually trust the 10Kv raiting on the front LOL, and How long Nixie tubes last? Like if these tubes need to be replaced will it be hard to find a match?

author: AF6LJ
author_rank: Unknown
timestamp: September 22, 2015, 12:49:41 am
content: I worked for a small two way radio shop in the mid seventies that had one of those.2.5 digits was a big deal then.

author: JoeB83
author_rank: Regular Contributor
timestamp: September 22, 2015, 01:36:05 am
content: Neat! I love nixie tubes.

author: crispy_tofu
author_rank: Super Contributor
timestamp: September 22, 2015, 01:41:11 am
content: Wow! That looks like it's in great condition ... great score!

author: tautech
author_rank: Super Contributor
timestamp: September 22, 2015, 02:22:11 am
content: Teardown or at least inside pics.

author: bitseeker
author_rank: Super Contributor
timestamp: September 22, 2015, 03:16:48 am
content: Nice score. Definitely a keeper.

author: Xenon Photon
author_rank: Unknown
timestamp: September 22, 2015, 03:23:25 am
content: How old is that?Can you post tear down photos?

author: lowimpedance
author_rank: Super Contributor
timestamp: September 22, 2015, 03:26:43 am
content: Really 'old timer' classic, I'm with tautech etal, we need to see some nice exposed internal pics.

author: retiredcaps
author_rank: Super Contributor
timestamp: September 22, 2015, 04:02:15 am
content: Modemhead's teardown.http://mrmodemhead.com/blog/nixie-glow/

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: September 22, 2015, 05:03:54 am
content: Well theres some pics I guess lol, I will definately open it up and take pics of mine, id like to see the construction, theres a youtube video all about this meter athe explains how the kit works etc... As he says in the video the IM version was a kit and I think SM was prebuilt so I would like to see how well mine was put togather, on top of playing with the trimmers

author: AF6LJ
author_rank: Unknown
timestamp: September 22, 2015, 11:50:53 pm
content: Good video, as I mentioned above I remember using that model of DMM, it was at the time quite good for the money.

author: radhaz
author_rank: Regular Contributor
timestamp: September 23, 2015, 03:03:01 am
content: Interesting history:http://www.pa.msu.edu/~edmunds/DVM_HP_3440a/digital_volt_meter_history.txtLucite blocks!

author: AF6LJ
author_rank: Unknown
timestamp: September 23, 2015, 03:15:21 am
content: Quote from: radhaz on September 23, 2015, 03:03:01 amA college classmate had an NLS DMM that was built in the mid 60s 3.5 digit discreet transistor built on three circuit boards and took up half a rack space width.One of these days I am going to lay my hands on an HP-3440 DVM.

author: Cubdriver
author_rank: Unknown
timestamp: September 23, 2015, 07:49:16 am
content: O.P. - very cool find! I built a Heath IM 2202 digital meter back in high school. It was a neon display, but not truly a nixie - instead it had (IIRC) a two digit 7 segment tube and a 1-1/2 digit tube that also held polarity indicators. The display tubes were flat faced plug ins, something like a VFD form factor but neon instead of fluorescent. Unfortunately the batteries corroded and like an idiot I tossed it about 20 years ago during a cleaning binge.Quote from: AF6LJ on September 23, 2015, 03:15:21 amI was actually just playing with one of those earlier today. Purchased from EvilBay a while back. I re stuffed the three can electrolytics, but couldn't get it to respond to either the -8V calibration check or an external input. At some point during my several hours of puttering around tracing signals and finding nothing apparently amiss, I happened to look at the display and the damned thing had started working again.I'm unsure if it was a bad connection that was fixed by reseating something, or if there were smaller electrolytics on the boards that re-formed whil it was cooking, but it seems happy now, and zeroed & responded to the -8V cal quite nicely. Pretty impressive considering it's pushing the half century mark. (It was built in 1966.)More photos at:https://pmanning.smugmug.com/Electronics/HP-3440A-DVM/52088921_r2zwVXand I have still more yet to add showing some more of the boards. (Hopefully the link works, this is my first try at posting images and links here)-Pat

author: AF6LJ
author_rank: Unknown
timestamp: September 23, 2015, 03:29:51 pm
content: Nice find, no telling why it decided to start working.I love the look of and the build quality of that old HP Iron.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: September 23, 2015, 04:13:44 pm
content: Very nice score indeed!

author: Seekonk
author_rank: Super Contributor
timestamp: September 23, 2015, 04:23:23 pm
content: Nothing beats an old NLS with stepper relays. I used to put a cap on the input and let it discharge over a couple minutes. Sounded like someone putting hundreds of nickles in an old Coke machine. I need to resurrect that. It also had these reed relays potted in epoxy that would crack and tear the wires.

author: MisterBiscuit
author_rank: Unknown
timestamp: September 25, 2015, 08:46:38 pm
content: That was one of my first meters ever when I was a kid! Neat!I recall that "calibrating" it was an almost comical event as the main oscillator had so much drift that calibration was pretty much pointless.

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: September 26, 2015, 02:23:40 am
content: Ya it is in pretty good condition, I went to home depot and had them match the blue top, it could use a touch up. So here is a picture of the inside of mineSome of the joints look like they need a touch up, I basically just opened it to spray it down with some alcohol and check out the solder work. One thing that strikes me as kind of strange is the ground strap from mains to chassis.... the actual AC cord has three wires but there is no ground prong, Im wondering if it was purposely omitted to keep the meter floating or if the kit came this way. Apparently someone bought the right to all the heath kit documentation so its not in the public domain :/

author: PaulAm
author_rank: Frequent Contributor
timestamp: September 26, 2015, 03:06:02 am
content: If it weren't so heavy, it'd be fun to have a whole suite of nixie equipment. I have a 3450a and 3450b multifunction meters. 5 1/2 digit nixievoltmeter with ohm and AC options (the a has the options, the other is just a dvm). I got one cheap because someone had stripped the nixie board out of it and then I managed to find one on ebay. They compare quite well with my uncalibrated 3456a.Way cool

author: Cubdriver
author_rank: Unknown
timestamp: September 26, 2015, 06:06:48 am
content: Quote from: PaulAm on September 26, 2015, 03:06:02 amDamn you, now you've given me something ELSE to hunt for on evilBay!!I DON'T need extra help in that department, I can get in enough trouble unassisted, thank you very please!!-Pat

author: Cubdriver
author_rank: Unknown
timestamp: September 26, 2015, 06:16:01 am
content: RW, that looks like a nice little meter. Very clean inside.Weird about that ground. Are you saying that the cord itself is three wire, but the plug is two prong, or was the plug modified at some point? If only two prong, is the plug polarized?Ugh! Is the Heath stuff still all private? I thought I'd heard a while back it was being released again - evidently not. A pox on whoever it is that bought the rights and then locked it down. Not cool. I understand that if they own it they can do that, but it's still a scum move IMO.-Pat

author: PaulAm
author_rank: Frequent Contributor
timestamp: September 26, 2015, 12:55:48 pm
content: Quote from: Cubdriver on September 26, 2015, 06:06:48 amJust passing it onI got hooked on looking for one of those after seeing it in this thread:https://www.eevblog.com/forum/projects/pearls-of-the-past-%28only-for-the-voltaically-inclined%29/People strip the nixies out for clocks and dump the rest; it's getting hard to find one intact. Took me about a year to track mine down.

author: Cubdriver
author_rank: Unknown
timestamp: September 26, 2015, 03:13:56 pm
content: People stripping the nixies for clocks is heartbreaking, since they're so easily available from Eastern Europe and Russia as NOS. I got into the nixie thing from the mention of the HP 5245L on the HP list, and have been hunting for other stuff containing them since. Thus my interest in the 3440 I mentioned earlier.-Pat

author: AF6LJ
author_rank: Unknown
timestamp: September 26, 2015, 03:20:12 pm
content: Quote from: Cubdriver on September 26, 2015, 06:16:01 amSadly it looks like Heath will not be brought back from the dead. Maybe this is as it should be. Heathkits cost more than their assembled counterparts because when you finished you had a product that looked factory made. Heath Knight Eico were all like that. I really don't think the new kits could measure up to the quality of the old Heathkits. Having built a dozen of the heathkits of times gone by, I like to remember how much fun it was and how they turned out.

author: Robomeds
author_rank: Frequent Contributor
timestamp: September 26, 2015, 03:29:38 pm
content: Are the Heathkit meters any different than the Bell Howell meters?http://www.ebay.com/itm/Bell-and-Howell-schools-digital-multimeter-model-imd-202-2-with-manuals-/191700851334?hash=item2ca242da86The auction above had manuals with it that might include schematics etc.

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: September 26, 2015, 04:52:28 pm
content: No the bell howell are just rebaged for a tech school same meter.It is a three wire cord with a three prong connector. To me it looks like the ground prong was ripped out and the hole was stiffed with rubber.

author: edavid
author_rank: Super Contributor
timestamp: September 26, 2015, 07:04:25 pm
content: Quote from: Cubdriver on September 26, 2015, 06:16:01 amDon Peterson's ownership of Heathkit manual copyrights is disputed.Here's a site which has many manuals and schematics, including the IM-1202, which is similar to the IM-1212...http://tubularelectronics.com/?page_id=64