It's all good junk here.
Friday, January 16, 2026 at 06:34:03
It’s been a while since I’ve zipped up all the files in the document library, so it’s high time I do it again.
If you’d like a copy of everything I’ve collected for projects here, you can grab a copy of it from dropbox: https://www.dropbox. … ro3&st=djfaezpv&dl=0. The file is about 410MB, and is all of the files in a big .zip for easy extraction.
image courtesy of freepik
Thursday, January 15, 2026 at 15:10:41
Used to be every technician had a set of them in their toolbox. They were a required purchase when I was a student in vocational electronics. My set generally vanished years ago, and Radio Shack quit selling them long before they became a piece of history.
Turns out you can still get that exact same set. It’s not in the ratshackpack, but you take what you can get.
So I guess I’ll be over here playing with my diddlestick.
Thursday, January 15, 2026 at 13:55:14
I’m (more or less) done re-doing images here. I did find a couple that I messed up and missed, and a few that were deleted before I realized what I did (use that trash can!) but everything should be back in place. Thankfully, the Internet Archive had that all stored…feel free to submit pages there if you want!
What did I do?
1: Cropped a lot of images to show the relevant parts only. You don’t need to see a photo with 1/3 of it being the dirty mat on my desk.
2: Resized a lot of images so they are faster loading - a 2000×2000 image of a single resistor isn’t useful, and just wastes your time.
3: Moved a lot of things around on the back-end. I had images everywhere, but created folders for various projects and moved general images into appropriate folders.
4: Renamed most of the images so you know what they are if you download and store, and then come across the image some time later. The only things that didn’t get completely renamed were event photos since there’s a lot of those. They’re in their own folders, and that may be a project of it’s own.
Anything else?
There are a few document links still pointing towards my old OX drive. Those documents are still there for now, but you can find everything at the Wereboar Documents Library here: https://wereboar.com … r=wereboar-documents
I’m going to set a search on those old links and replace them as I find them, or simply point to the docs library in general.
edit: As best I can tell, all links to OX drive have been removed. I’ll leave the files there for a while, but probably will remove them no later than July of this year in case someone wants to grab them from an old link.
That all?
Yep, everything should be back in place, the pages should look better, and you should get image downloads a lot quicker. There may be some short delays as new thumbnails are generated for you, but I tried to take care of all those beforehand during preview setup.
As always, if you find anything broken, please hit the mastodon link at the bottom of each page and let me know. Thank you for visiting, and I hope you’ve found something of interest here.
Thursday, January 15, 2026 at 11:57:19
In the last part, we determined that this device was nothing more than a rebadged Heathkit AV-3, so documentation beyond the simple schematic was definitely available - including the tube voltages chart. That goes a long way towards an attempt to make this device work.
The Simpson 715 is a dedicated AC voltmeter in a small package. It’s not necessarily of the greatest use these days, but the package is kind of cool, so I decided to give it a go. It works, but won’t zero fully.
There are a number of capacitors in this meter, and some in the meter driver circuit itself. But for the most part, there are a number that must be replaced for continued operation, so I’m going to go ahead and get those replaced before continuing - and perhaps that will fix the zero issue.
For this part of the issue, the following capacitors (identified by a yellow box) will be replaced:
For the most part, these will be like for like parts, same value and voltage, except for the filter capacitor. This one is 150VDC, but it’s going to have to be higher voltage if I want to use this thing. Why? This little guy.
This selenium rectifier will need to be replaced as well. The problem here is that for a brief moment, the voltage on the filters is the rectified line voltage minus the voltage drop of the device. This is because until the tubes are asking for current, there’s no drop on the power supply divider resistor, and the full voltage appears on the capacitors. This isn’t a problem for a selenium device, which has a voltage drop in the 10s of volts. But, for a modern 1n4007, you’re going to have the full rectified voltage on the parts. It’s imperative to take the voltage of the filters up to a value that can withstand that.
Older parts may have also seen this higher voltage, but those old filter capacitors could withstand surges due to having thicker dielectric material and other construction quirks that we don’t use anymore. For this device, I’ve chosen 250VDC parts instead of 150VDC. I’m not going to replace the selenium rectifier until the device works, but that will be a future part of this series. For now, let’s just replace capacitors.
In order to do so, the unit has to come apart. The chassis is connected to the meter face at 6 points:
2 on the input terminals, these get unsoldered and removed for a cleaning bath.
2 on the meter itself, these unbolt and the board slides back.
1 on the switch, this is a nut that comes off.
1 on the pilot lamp, another nut that comes off.
Knobs, pilot jewels, and terminals all go in the ultrasonic bath for a much needed cleaning, and the face is left in an easy to clean state as well.
The meter itself is interesting. This being a Simpson device, they made their own meter movement and specified it be calibrated in a certain way:
We’re left with a chassis.
This is mostly just an exercise in delicacy, removing parts from old terminals. I get to use my new solder pick set here!
The big 0.033 on the switch goes first. This type of part tends to crack and leak. For some reason, I didn’t take a picture of it before coming off…
I may take that back off and put some ’sketti on it.
Next is that bumblebomb you can see behind the switch. These also crack and leak, although this one doesn’t seem to be one of the oil-filled capacitors. (By leak, I mean they absorb moisture and change value.) It’s not across the line, so no safety cap needed here.
I try to reuse the old tubing where possible, but some new was required.
Next is an electrolytic. A new part, much smaller than the old, goes in.
It never ceases to amaze me about the difference in sizes. Sure, the old ones had some advantages, but still…
The next one has to wait a while, but here is the part that will go in. Similar size comparison:
This part has a 680Ω resistor across it, and I’m going to replace both parts at the same time as the resistor is soldered directly across the capacitor’s leads. There’s also a 30Ω resistor after this pair that will get replaced, as all of these are directly on the meter legs.
I’m currently waiting on some parts to arrive and will install those when available. Stay tuned for part 3!
Next part of this series: https://wereboar.com … acitor-replacements/
Previous part of this series: https://wereboar.com … simpson-715-ac-vtvm/
Thursday, January 15, 2026 at 10:56:54
I purchased this meter at Dayton 2024 on Sunday. It was still in the box, had all documentation with it, and was in excellent condition save that the seller said it had one segment in the display out. I couldn’t pass it up for $20, considering it’s both that awesome 1970s blue and has some historical interest.
Sabtronics was a company that appeared in the 1970s. Based in Texas, they were pretty much the first company that offered a hobbyist priced digital voltmeter you could either buy as a kit or assembled. It offered 3 1/2 digits of precision, was fully calibratable by the end user, and even offered an optional True RMS module. Sabtronics offered other devices - frequency counters, signal generators, etc. - essentially your entire test lineup, all made in the USA for reasonable prices. The stuff even ran on batteries, if you so desired.
Unfortunately, the coming of the Japanese meters and equipment did them in, as they were unable to compete with prices offered for imported junk. Isn’t that a familiar story?
(I’ll post pictures of the box and the documents ASAP, I need to dig them out of their hiding spot!)
Here’s the front of the meter, and you can definitely see there’s a segment out.
This segment did work for a while, so I assume there’s something inside the LED package that’s broken.
The top is that lovely blue.
Inside is clean. There’s a spot for some extra parts. The displays are on their own board on a long ribbon, which should make replacement easy.
In the back is a battery holder. It’s broken, of course - that cheap plastic wasn’t very good no matter where it was built. It gets old and brittle. Was this why the device was retired?
These do have the option to run on 10VDC (!) which is a very odd voltage. I have a power adapter from another Sabtronics unit, which is what I’m running it on.
The back is normally covered by a cover that has a slide latch. I noticed that it didn’t set in the hole well, I assume due to age and plastic changing over the years. Attempting to put it back in made it crack, which is probably why every other Sabtronics device I’ve seen is missing the cover. I probably will reattach this piece with some extra plastic and glue, remove the battery holder, and permanently attach the cover. I don’t need to run this on batteries.
Ignore the extra parts, those are from the Simpson 715 that’s on the bench beside this guy.
So, does this thing work? Sure does, although I’m not sure if it’s correct.
One (or both) of those meters is wrong. I’m not sure who, but I’ll take the Sabtronics in to work and check it with our voltage calibrator. As for the display, I have some of the proper Fairchild displays on order from a NOS seller. Those should be here soon, stay tuned!
Next part of this series: https://wereboar.com … s-and-documentation/
Thursday, January 15, 2026 at 09:25:43
Well, it’s a zombie, but whatever.
Here’s a couple of devices I’ve picked up at shows and other places, both branded “Micronta.” The first is a small DVM that’s in a calculator-style case with old bubble LED displays. It’s a model as soon as I remember to look at that I’ll put that model number here.
Apparently, this is a clone/rebadge/rework of the Sinclair PDM-35, which came in a white case.
The back has a very dirty on/off switch and a jack for a power adapter. I think that’s one of those old 3/32” phone plugs that companies loved to use before coaxial barrels became popular.
It requires a 9V battery. Let’s slap one in and measure some volts.
The decimal point doesn’t move - you’re required to move it in your head.
The device’s big brother doesn’t really agree with the measurement. It’s close, however. How about some ohms? Like 330 of them?
Big brother really doesn’t agree here.
Eh, I guess for a dollar hamfest buy, we’re lucky it works at all!
The next device is another Micronta unit, also in some sort of calculator case. This is a Model 351 Counter, catalog number 22-351. Made for Radio Shack, of course.
It comes with a manual, case, and antenna.
They simply used a standoff inside the case as a mounting point for the antenna, which itself is just a piece of chrome plated screw rod. Cost savings everywhere!
The battery compartment on this one is clean, but the battery connector itself needs some love. It broke shortly after this test, so I need to find some new ones. It’s been years since I needed some 9V snaps.
It uses the same 3/32” phone plug for power, has a screw standoff for the antenna, and a 1/4” phone jack for signal input. I have a phone plug on some clips I use for troubleshooting, so let’s slap a battery in and connect it to a signal generator. I give it about 5KHz, which should be well in the range of this device.
And…nothing other than two dots. I get some numbers rolling around when inserting or removing the plug, so the device is probably counting when triggered - but isn’t triggering.
Inside is a simple circuit - some glue, a big 6 decade upcounter IC, and some chips.
Yes, that is a National Semiconductor logo there…they made the display board, which the manufacturer of this device just purchased whole.
I plan on doing some checks on this thing, starting with the oscillator - but not today. This goes in the pile for later.
Stay tuned!
Next part of this series: https://wereboar.com … -odd-heathkit-stuff/
Previous part of this series: https://wereboar.com … -ps120-oscilloscope/
Thursday, January 15, 2026 at 08:23:45
About a year ago, I had a small Waterman “pocket” scope on the bench. It needed some tubes, and had a bad power switch. In an effort to clean up the pile ‘o stuff waiting for bench time - here it is.
First thing I wanted to do was verify that the switch was indeed open, and it was:
By the condition of the unit, it was used quite a bit. Maybe one of the conditions that cause this device to be retired was that open switch. It was easy enough to fix, just a jumper across the terminals. Before attempting to plug it in, I verified that it had a fuse in it, and it was good.
There aren’t any shorts, I can see the transformer load on the cord. Plug it in! I can see tubes lit.
But, there’s nothing on the screen. I mess with the controls for a while and let it set. Nothing. Upon powering down and opening, I notice I can’t detect any heat on the neck of the CRT. Well…it may be open or have some other fault. That’s a show stopper here, and I remove my new tubes for later use.
This guy goes into the donation pile. Perhaps someone can make use of the parts.
Previous part of this series: https://wereboar.com … oscope-part-2-tubes/
Wednesday, January 7, 2026 at 14:01:23
When I started this blog, I didn’t quite understand the way the image function of flatpress worked - I’ve made several changes over the years but none of them were really satisfactory to me, or even standardized.
I’ve decided to start at the beginning and clean up images, resizing loose images (those not in a gallery) to more standard sizes, adjusting them so they aren’t all over the place in the posts, and generally providing a cleaner look. I’ll crop junk off of them so you just get the part that’s important, instead of a tiny part in a big image. I’m also moving images to more useful locations within the site, collecting posts together so they’re not in random folders.
This is going to be a long project, but older posts should start to look better for you - and perhaps even load just a tad quicker since they won’t be megabytes long. There may be some broken things while I move folders and optimize images, but they should resolve quickly.
So…in honor of the old web - here’s an under construction gif.
Project Status
2021 - Nothing to do.
2022 - Completed January 8th 2026.
2023 - Completed January 9th 2026.
2024 - Completed January 14th 2026.
2025 - Completed January 15th 2026.
2026 - Already using the new format.
Cleanup - Completed January 15th 2026.
QA - Completed January 15th 2026.
Cleanup will involve removing old folders and other leftovers, and QA will consist of going through the entire blog, making sure links all work, and correcting any document/image links that are not using the new format. It’s going a little quicker than I expected, I have some downtime and have been hitting it hard. Stay tuned for some more equipment posts, coming shortly.
In-between cleanup and QA, things may break. I’ll fix them as I see them.
January 15th 2026 - I think we’re done…if you see anything broken, please let me know on mastodon.
Galleries for late 2025 may break, but I’m trying to avoid doing that. If you hit a post and there’s nothing there but a “directory doesn’t exist” message, try again in a day or so - I should have everything image pointing to it’s proper location by the end of the week. I think I have these fixed.
Wednesday, January 7, 2026 at 08:26:36
While not really a “recent” acquisition, this oscilloscope was something waiting it’s turn on the bench. This came from the Fort Wayne Hamfest in 2024, and was - for the most part - taken because it was offered for a few bucks. I took it because I didn’t want to see it get tossed in the trash, and wanted to give it at least a chance.
I never really had any intention of using the device, but the rusty crusty case was interesting. Would it still work? Who knows. I also never really had intention of fixing the device, so there’s that. The device itself is a Sencore PS120 12MHz oscilloscope, and dates to about 1966.
Upon investigation, the obvious problems are, well, obvious. The case is very rusty as if this thing sat in a damp but not wet location for some years.
The face is similarly dirty, like this thing was in a barn or something.
There’s a lot of dirt inside the unit as well.
Of note here is the CRT, made by DuMont. The tubes themselves are a mix of brands, with the Sencore name still on about half of them. There’s nothing special here other than the CRT.
However, when looking into the chassis itself, there is one interesting note:
There’s a lot of Sprague Orange Drops in here, and I doubt those are original. I’m guessing someone was in here trying to solve problems. So let’s plug it in!
I originally thought about using my death cheater to power this thing, but the power input terminals have exposed holes. I soldered a power cord in and did some basic checks. The power switch works, and the resistance across the line is about 9Ω. That’s good, it’s the transformer primary. That’s not shorted, so let’s raw dog the thing. I plugged it into the isolation transformer with a 2A current limit. Hit the switch, and…
I get a dot on the screen. Great! However, nothing else. Focus and intensity work, but anything to move the trace doesn’t work. No manual movement, no sweep, no nothing. I’d guess this is why there are so many new capacitors in the thing, the previous owner was trying to fix this problem and gave up. The Internet says to replace capacitors and it will fix everything, but that doesn’t always work.
It does have a good CRT, and someone can probably use that. I remove my cord and will put this into the “Donate This Stuff” pile for later disposal.
That’s all for this one, it was either going to be a work or don’t situation, and it don’t work.
Stay tuned for more junk!
Next part of this series: https://wereboar.com … 3-radio-shack-lives/
Previous part of this series: https://wereboar.com … cent-acquisitions-1/
Tuesday, January 6, 2026 at 12:58:44
This is going to be the first post in a seldom-series of equipment checkout posts. I’m going to take the unit apart, see if there’s anything that would prevent it from being turned on, do some basic “look here” things, and then turn it on.
This first post is two late year purchases, one from the Cleveland hamfest, the other from Fort Wayne.
This first one comes from Cleveland, and is a standard two-tube capacitor analyzer with an added headphone amp so you only needed one instrument on your desk. It probably designed for a set of high-impedance headphones of the WWII surplus variety, and much of the unit is built from surplus parts.
This was made by the Superior Instruments Company of New York. It’s in decent enough shape for the age. It’s complete, and has little damage to the front panel - but is in dire need of a cleaning.
The back of the unit is rougher, but would most likely clean up nicely with a good scrub. We don’t even get a cord grommet here. The power cord itself is a nice gray-blue that matches the case, but is quite rock-hard at this point.
We don’t even get an underwriter’s knot here, the cord is just draped across the chassis with no thought as to how it affects the circuit.
The chassis is about as cheap as you can get. A partial internal contains almost all of the components and tubes. Tube complement is:
1626 RF Triode being used as a diode (!)
VT-153 (12C8) being used as a headphone amplifier
1629 Magic Eye
All of these are mil-variants, which suggests they had lots of cheap surplus tubes. The triode is of particular interest. The manufacturer tied the control grid to the plate, making a diode out of the device. This tube also has a lower heater current than actual rectifiers, so they could use a smaller transformer. A way to use up what most likely would have been very cheap tubes that were of little use otherwise (the 1626 is a very low gain RF amp,) and as a way to use a cheaper transformer. Cost-reduced all the way.
The bottom of the device contains most of the leaded components of the unit.
There’s probably some surplus here as well, especially those silvery capacitors with no other markings. Of special interest is that big motor starter capacitor to the left - it’s not even marked on the schematic. I also like the red Astron part in here, all by itself.
Speaking of the schematic:
The device I have and this schematic only agree so far as “yes, there is that type of part in that circuit.” Not much else does - it looks like Superior probably used whatever they could get their hands on that was close enough.
Note the 2.0μF motor starter capacitor isn’t on the schematic - it should be connected to the power factor control. Who knows if this was omitted, changed, or added after the fact. Considering this was as cheap as could be, I would guess that the person who drew it was trying to be cost-effective, but it was found out later that the circuit didn’t quite work as planned. Other capacitor analyzers I have with a power factor measurement have a big capacitor in that circuit, so…whatever. There it is.
I don’t see anything that would prevent this from working, so let’s plug it in and see if there’s smoke!
The eye tube lights up. It’s acceptable, and can be seen in a lit room.
There’s no other power indicator on this device. I guess you really don’t need one.
DC on the power supply is kind of bleah, especially for having almost no current draw. This may be a symptom of using the wrong tube in the wrong place, or a bad filter. I didn’t stick a new filter in here, that may happen later. This is just to see if it works.
So, let’s put a capacitor on it. I chose a 8μF “Mighty Midget” removed from a previous rebuild. It’s gone quite high, so we should see something well in excess of 8μF.
The device seems to indicate this is about 14μF and change - we’re reading the top portion of the middle scale.
Let’s get a second opinion.
The second doctor disagrees with the first. However:
Doctor #3 agrees with doctor #1.
So, this device is probably as accurate as this type of device can be. It goes back together for later potential rebuild.
Next up is another IG-72. I purchased this at Fort Wayne, mostly as a spare for the one I already have. It’s in ok shape.
The back is likewise in not terrible shape, and has some interesting markings.
Of note is the fact that this one has a grounded cord, whereas others I’ve seen do not. There’s also the stamp in the corner.
It says “MEISINGER BEECHCRAFT, INC.” and was apparently part of their repair area test equipment. That’s really cool, this one has a history.
It was certainly used, but not abused:
It has the obligatory soldering iron melted spots. It was also millerized - whatever that means.
The inside is clean, but dusty. The transformer is a bit loose.
Tube complement is:
6X4 Rectifier
6AU6
6CL6
The CL6 and AU6 form the oscillator and output amplifier pair. It’s a standard Wien bridge oscillator with a light bulb in the middle as a PTC resistor. Two of the tubes are most likey the original Mullard tubes, and one is an RCA.
The bottom looks to have been factory built.
The bulb was goop’d in, probably to keep it from vibrating out during use in a running aircraft.
Nothing sticks out as preventing operation. Let’s pull the rectifier, as these liked to arc across the cheap socket.
Nope, that’s good. Time to plug it in. Power is applied. We have tube lights.
The needle comes up, and look there - this one still has it’s little red film for the power lamp.
The DC on this one is so clean, I can’t get anything off the power supply. The output is equally clean.
The signal does distort a little at the bottom of the wave when it’s turned up to full output, but that’s a known Wein bridge issue. I can dial it back a little and probably be fine.
That’s all for this one - other than some cosmetics, this device is fully operational and seems to be in great shape.
I’ll have more in this series as I pick up more devices. Stay tuned!
Next part of this series: https://wereboar.com … -ps120-oscilloscope/