- 2024
- Apr
- 7
Remember these things?
The Radio Shack crystal radio kit - a tuning capacitor, ferrite antenna bar, and a 1N34A diode on a little breadboard device that was reused for many different things - including an AM transmitter kit. These generally ran $10 for years, and this appears to be a later unit made in China.
I had one of these when I was a kid, but didn’t really appreciate it. Now I do, so I found one on an auction site and plan on building it. I’ll scan and post the manual as well, so stay tuned!
I would like to find out what the bar antenna is, and if they’re still available. They seem to have a million uses.
If you’d like a manual scan, you can download it here. It’s about 1MB, and is a 600DPI PDF: https://privateemail … 8376/1/8/NDY/NDYvMTY
- 2024
- Apr
- 7
An Eico 145 Signal Tracer - Part 2
It’s not really important to operation, but having clean knobs and lenses on indicators is always nice. Since I have an ultrasonic bath, I’m going to use it.
The knobs on this guy are pretty cruddy, and the power indicator has a spritz of bronze paint across it.
While I’m removing the knobs from the volume and function selector, they get a shot of deoxit to clean and lube them.
Everything goes in the bath for 20 minutes.
In the end, they all come out nice and clean and ready to re-install!
Parts have been ordered, we’ll go through those next.
Next part of this series: https://wereboar.com … ignal-tracer-part-3/
Previous part of this series: https://wereboar.com … ignal-tracer-part-1/
- 2024
- Mar
- 28
By the power of the sun!
Remember these things? One of these kits (the 160-in-1 to be exact, which I still have) got me into electronics.
This one is a kit that I always wanted to get, but it never seemed to be available when I had the money. This particular example came from a popular auction site, new in box - even the crappy earphone is there! And yes, I plan on sitting down with it and building a few of the things in it.
It’s kind of a shame that stuff like this isn’t as easily accessible as it once was. Certainly, parts, microcontrollers, and other electronics are far easier to find - but this guided, all the parts are there all the time, no extra stuff save some wire needed kits don’t seem to be around these days. Perhaps the limited use doesn’t appeal to people like it did then?
Regardless, I didn’t necessarily know what the parts were doing, or why, but I knew I wanted to know more.
I salute you, humble kit of parts. You were (and still are) a wonder in a small box.
- 2024
- Mar
- 17
An Eico 145 Signal Tracer - Part 0
I sat down with an Eico 145 Signal tracer this weekend, evaluating what it would need to put it back into daily service. The answer? Pretty much everything. Leaky wax capacitors, carbon comp resistors that are 50% off of their marked value, and a few “doesn’t appear to ever have been installed” parts complete the list of this thing’s issues. It’s amazing that it’s still working, but I would bet that continued operation would destroy the tubes in short order.
The large 470Ω resistor in the foreground was of interest. A quick shout out to a friend confirmed that this was a 2W part, not a high-voltage device. This makes sense, as the resistor could potentially dissipate 600mW at maximum plate current. It’s also interesting because there’s supposed to be a 10uF bypass capacitor across that part, but it looks like it was never installed!
Right under that, of course, is the across the line capacitor. That ’splodey boi gets replaced first.
A quick trip to mouser for components is in my future.
Next part of this series: https://wereboar.com … ignal-tracer-part-1/
Previous part of this series: https://wereboar.com … o-145-signal-tracer/
- 2024
- Mar
- 12
An unusual 115VAC demand meter.
I picked this unusual device up from an antique store in rural Pennsylvania, near where the groundhog works one day a year. It’s a fairly large place and prices vary, but it’s worth a couple hours of your time if you’re into that sort of thing, see the link below.
(The place seems to only have a facebook presence, and I’m not going to post one of those dirty links here - but here is the local chamber’s page for Yoder’s Antique Mall in Punxsutawney: https://punxsutawney … 73c05f142052452104c6.)
It’s a toolbox! Yeah, right on! Well…no, unless you’re interested in old toolboxes. It’s a fairly nice example of something from when Sears used to make things worth more than the metal it was stamped from. It’s what’s inside that I was interested in.
It’s a demand meter! Yeah, right on! Well…yes, but there’s something unusual about this one. It’s a 2-wire, 115VAC unit. While this is similar to what you would have on your house (or would have had before the electronic switchover,) those are usually wired for 230VAC instead.
This one appears to have been meant for sub-branch metering at some point, as evidenced by the easy-to-remove wiring compartment at the bottom of the meter’s housing. Whomever had this before me took advantage of that in that they wired a plug and outlet in line with the device - perhaps as a jobsite meter to pay the site owner for power consumed? Not really sure here save that all of the cable is pretty stiff and in need of replacement if it was going to be used.
Overall age of the device is in question as well - it looks to be 1930s, but Westinghouse probably made these things for decades. I suppose I could try and track it down by serial number, but who knows if those records still exist?
I tried it out by hooking it to a kitchen appliance with a heating element. It works as expected.
I’d like to get it out of it’s silicone covered metal box for a good cleaning, but that’s a project for another day.
- 2024
- Feb
- 10
Magic Eye Tube kits from China
I picked up a couple of small kits from everyone’s favorite Chinese junk store, Aliexpress:
They appear to be the same base kit, except that one has an EM80 cat’s eye style tube, and one has an EM84 style side-looking tube. There was also a 200V power supply included with one of them, but I’m not sure which one it was at this point.
There are absolutely no instructions to speak of, but the boards seem to be well labeled. It shouldn’t be too much trouble to get these together, assuming all the parts are correct.
I’m planning on assembling these in a few months (as time allows,) so check back to see if they’re done and my thoughts on assembly and operation.
- 2024
- Jan
- 23
All of the documents currently in wereboar’s archive - Part II.
I’ve added a few more documents to the Wereboar archive on both the previous entry, as well as this (new) entry. More will be added as I gain more manuals for equipment featured here. These are hosted by my webhost’s cloud storage system, OXDrive.
Original document archive post:
https://wereboar.com … n-wereboars-archive/
The Knight KG-690 and 83Y135 Signal Tracer (Same chassis, different cabinet):
https://privateemail … 11cf/1/8/NDY/NDYvMTU
Radio Shack “Science Fair” 28-177 Crystal Radio Kit Owner and Assembly Manual: https://privateemail … 8376/1/8/NDY/NDYvMTY
All of the documents currently stored in the wereboar archive, as of April 8th 2024 (165MB zipfile) - anything below this is not in this archive:
https://www.dropbox. … w2v18oho5tib9vu&dl=0
The EICO Model 540 Readi-Tester:
https://privateemail … ed43/1/8/NDY/NDYvMTc
- 2024
- Jan
- 20
Magic Eyes - glowing green magic from the vacuum tube era.
One of the most interesting and accessible pieces of tech that came out of the tube era is the Magic Eye. A phosphor cup (or target) is illuminated with an electron beam, and a grid allows or blocks that electron beam to “open” the eye. It’s a device that can indicate changes at the speed of the phosphors used, and it found it’s way into all kinds of devices - radios as tuning meters, signal tracers as signal indicators, capacitance checkers as a quality meter - anywhere a fast visual change needed to be shown to the user.
These two signal tracers, one branded Knight, the other Eico, have eye tubes as their wattmeter and signal indicators. The Eico’s eye is so bright it overloads the camera, while the Knight’s eye shows much more use in it’s dimness.
While eyes fell out of favor as meters, VFDs, and other electronic indicators came into their own, they still remain one of the most striking devices in mid-century electronics.
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- 2024
- Jan
- 15
That oddball connector on old test equipment…
You know the one I’m talking about - this thing:
It’s a Switchcraft 2501f Microphone Connector. It found it’s way into low-frequency RF devices after WWII, where it remained until displaced by the superior BNC connector.
They’re still available, but they are not cheap - expect to pay $14-15 for a new one! If you’re not worried about looks, just replace it with a BNC and be done with it, you get access to a wider range of connections.
You can view the data sheet here, or order one from Mouser.com here.
(not a sponsored link, just a company I’ve had good luck with over the years!)
- 2024
- Jan
- 8
Stabilizing the oscillator in the IM-1212 Meter, part 2
One of the issues with the IM-1212 and it’s clones is that it drifts all over the place, and part of that is the oscillator that actually does the counting for the display. This is an attempt to replace that section with better parts to see if it’s any more stable. I started this with this previous post, and present my findings here.
We start by identifying the components of interest and removing the board:
In the oscillator circuit, other than the transistors, are the following passives:
15k
8.2k
3.3k
3.3k
0.0022uF
0.0022uF
15k Potentiometer
We’re not going to replace the pot, but all of the other components are going to be replaced by film and/or temperature stable to 25ppm components.
The sharper-eyed among you will have already seen an issue. There’s no 15k resistor identified here, and I’ll talk about this a bit later in the process.
Before taking the board out, I let it warm up and preset the oscillator to it’s suggested 85 count.
Getting the board out isn’t too bad. There are 6 screws, three solders, and a clamp.
The screws are the ground lug for the power cord on the back panel, the two screws that hold the transformer down, and one screw each in the remaining corners. One of the screws is under the switch assembly and can just be seen by the red input jack, so you’ll need something relatively thin and long for this one. They all appear to be the same size.
Next are the three jacks on the input. I unsoldered these at the front panel itself, but the white wire was long and flopped around and broke because it is solid wire. Not a big deal there.
Last, is the clamp for the power cord on the back panel. This is just squeeze it with pliers and work it out. I left the power cord attached to the unit and just pulled it through the bottom case so I had enough room to work, and used the ground lug screw and nut to temporarily hold the transformer down as not to break the relatively fragile connections to the PCB.
Before getting started, I did an inspection of the board. There were a number of bad solders on some of the components - mostly things with thick leads like the potentiometers. I took a minute to clean those up before getting started.
Removing the parts is relatively easy, this being a single sided board. A soldapult and some wick made short work of the old solder, and that’s when I noticed the 15k resistor wasn’t.
The schematic indicates 15k, as does the board - and another unit I have has the correct 15k part in it. I have to wonder why this was there - did the original builder not get the correct part, or was it broken during assembly? Who knows - but it didn’t really matter as the device worked.
Interesting.
The rest of the parts are replaced without issue, and the correct 15k is placed where indicated.
There’s not a lot of current or voltage here, so I wasn’t particularly concerned with the size of the resistors.
After doing a precursory check of parts, solders, and whatnot, I powered the device up on the bench. The oscillator count was quite different, so my replacements had some effect.
Some warmup time later and I adjusted the oscillator to the correct value:
Putting it back together and:
It’s already drifting. I set it back to 85 and let it set until the next day.
It didn’t do a thing. I will say, however, that it seems easier to adjust it back - there’s not as much play in the overall adjustment - you can set it and it generally stays there until the temperature changes.
So, my conclusions? This whole thing probably would need rebuilt with modern components in order to maintain any stability in measurement. For now, it’s just going to be sitting in a rack on all the time measuring the 12V rail of a power supply so … it is what it is, I guess.