- 2023
- Nov
- 21
Notes from the Fort Wayne Hamfest
Fort Wayne was pretty good this year, and I have a lot of pictures to process and upload.
In the meantime here’s a bit on a device I picked up. It’s a 2 1/3 digit DVM made by … I don’t know. I’ve seen it sold as Heathkit, Bell&Howell, and others. It’s not the most accurate thing in the world, but it was easy to put together and looks to be a good tool for teaching basic A/D concepts. It’s very drift-y, and from what I can tell was known to be such even when it was new. It’s still cool, however.
It required some minor work and adjustments to get it up and running, which I’ve documented and will post later - but in the meantime, here’s the device doing integrations on a low speed sine wave. It counts as fast as the TTL silicon will allow it.
(If the below gif doesn’t play, click on it.)
Stay tuned for more electronics junk good stuff!
- 2023
- Oct
- 25
Testing the Aliexpress Supercapacitor UPS.
Some time ago, I picked up two supercapacitor UPS devices from Aliexpress.
They’re 22F, 12V in, 5V out, and run about $23 per with free shipping. They’re available here: https://www.aliexpre … 256804670683100.html if you’re so inclined. This isn’t a suggestion or reccomendation, just one of the places you can get this item.
Within the sales page is an output time chart:
But who knows if this is correct, it wouldn’t be the first time that a vendor has overrated the capabilities of a new technology. I decided to set up a test of my own to see what happens. For this test, I selected the following items:
A 2A 12V switching wall wart from an old hard drive.
The Supercapacitor UPS, “Bundle 2” from Aliexpress.
A 0-10V laboratory meter.
A 0-1A laboratory meter.
A Rat Shack “Micronta” digital voltmeter.
An Orange Pi 1 with display in a “Monitor-IO” case.
Cables and connectors.
Specifications of the UPS itself:
Input: 12V via screw terminals or barrel jack.
Output: 5V at 3A max via USB-A or screw terminals
Charge and power indicator lamps
There is a version that is 12V output on both the screw terminals and USB-A jack, so if you make a purchase insure you are getting the right model!
Hookup is relatively straightforward, so I’m not going to draw a schematic, but: 12V goes in to the UPS, and comes out the 5V side. A voltmeter is across the load, and an ammeter is in series with the load. The load, of course, being the Orange Pi 1.
The Orange Pi 1 is an Allwinner H3 Quad-Core A7 CPU and has 512MB onboard. It’s booting from a uSD card and powers a simple 2-line display with RGB backlighting. It’s currently running the standard Armbian build with a ping monitor program.
Originally, this device was sold by a company called Monitor-IO as a network monitoring and intrusion device. When the company shut their doors (and the backend of the device,) they provided a simplified version of the applications for those of us who had the devices. Other than their special sauce, it’s simply a standard OP1 with Linux.
Booting the device reveals that it will spike to about 400mA of current draw, but settles down to an average of around 180mA with minor spikes as the network is accessed. These are very small in time and current consumption, so they don’t really affect much.
Voltage output while charging is 5.35 volts, and current draw on the testbed is about 180mA.
First test was to see how long the device takes to charge. With 12V 2A input and 180mA output, I observed the following approximate times. These are times indicated by when the charge indicator LEDs lit fully, and are approximate because some of it is subjective:
1st LED (Red): 180s
2nd LED (Grn): 240s
3rd LED (Grn): 330s
The LEDs have a very fast flicker while charging, and you can kind of see this when you squint at it. When the flicker vanished, I assumed that the device had reached full charge, which happened at about 5m 30s. I’m going to assume that no matter what kind of current you give it, this is going to be limited as not to short-circuit the input power supply when the capacitors are charging.
Second test was to see how long the device will hold itself up before charge is exhausted. As with the charging test, each of the times is when the appropriate LED went out. I did observe a voltage output change during this time, which is noted below. Each of the noted times is from input power removal, and again, is approximate.
Power drops to 5.00V: 5s
1st LED (Grn): 240s
2nd LED (Grn): 280s
3rd LED (Red): 346s > power off.
The output at power off drops to 0.603V, and stays there for some time.
At 180mA, you get well over 5 minutes of up-time to safely shut down your machine. If we extrapolate this up to 1A, you should get about 55s of up-time, which corresponds to the life chart and is still plenty of time to shut your machine down safely, assuming you do it within a few seconds of power failure. The device offers a soft-switch to signal power off events to the device in question, if you’re so inclined - but I did not test this as it’s not going to meet my needs. I’m planning on spinning up a simple board with some reed relays on it to provide my monitoring equipment a dry contact for notifications.
In all, this is fine device for smaller SBCs and any device that’s running on 5V, and you don’t have to worry about replacing batteries. It’s not going to be useful for some of the newer devices that require up to 5A of 5V, but for the device in question (and probably things up to the Pi2/3) it’s a good, cheap solution - something that’s quite rare in this day and age.
The only things that may trip you up are the slightly high 5V when there’s input power, and the 0.603V after power off. Most SBCs probably won’t mind either of these, but if you have a sensitive device it could cause problems.
I give these devices a thumbs up, and plan on implementing a few of them around the network.
- 2023
- Oct
- 20
I finally got around to testing the supercapacitor UPS.
It’s been sitting on my desk for a while, waiting for some time. Now that the weather has turned towards rainy fall days, some time has been found (and no, I don’t have any extra, sorry!) There was nothing really surprising found, and I’ll publish my results once I get them written up into something coherent. Stay tuned!
- 2023
- Sep
- 29
Did Espressif fix their RF spurs?
Some time ago, I wrote about my experiences with the ESP8266 line of microcontrollers. Specifically, that they had a giant RF spur at 319.98MHz. This wasn’t an unknown issue, the FCC documentation (had I read it beforehand) clearly called that out. See this post: https://wereboar.com … of-cheap-technology/ for more info on that.
Recently, I picked up this little gadget from a well-known overseas marketer. It works amazingly well, although I suspect this one of having hacked firmware… The MAC it gives to the router clearly identifies it as an Espressif device.
One of the things I immediately noticed, however, was that there isn’t a spur. I was running my devices in a similar manner, they were simply consuming data while being connected to a WiFi interface. I have to wonder if Espressif has fixed that issue, or if the firmware is doing something odd to keep that in check. More investigation is needed here, and perhaps a new look at my old designs is in order.
- 2023
- Sep
- 28
An infrared camera for about $40
Within the last 10 years, low resolution and correspondingly cheap IR sensors have come on to the market. Ranging in size from 8×8 to 32×32 pixels, these devices have shown up in many projects and purchasable items.
This type of IR sensor isn’t a camera per se, but instead is a grid of temperature sensors that a processor assembles into a visible image. You could just as easily have a grid of temperature readings instead of the visible image.
One such series of sensors is the AMG88xx series from Panasonic, and probably other vendors with less recognizable names. Costing around $20 from various sites, this 8×8 sensor is cheap enough for the hobbyist.
They’re available direct from the Chinese assemblers: https://www.aliexpre … 256804493110749.html
However, for not much more you can get one assembled into a small package with a screen: https://www.aliexpre … 255801147595884.html
(These are not suggested purchase links, but examples of item cost. I’ve used Aliexpress quite a bit over the years, you generally get what the listing shows - just be careful and make sure you’ve selected the correct item, as they tend to have multiple items in the same listing and sometimes you don’t pay attention and get the wrong item.)
I purchased one of the fully assembled units, received it the other day, and gave it a try. I received exactly what was shown in the listing, a camera module, a screen and CPU unit, all assembled into a couple of pieces of plastic sheet.
There’s no battery, so you have to plug it in to a USB or other 5V source via the Micro USB on the side. It comes up immediately with the image.
Here’s a hot cup of tea. You can clearly see the hot spot, even if it’s not well defined. The temperature reading is in °C, and there’s no way to change that. Not a big deal.
A glass of cold water from the tap.
And a cold drink that’s set out for a while.
This, like most devices of it’s kind, auto-scales the temperature colors so the hottest spot, regardless of actual temp, is red. That’s a nice feature and gives you a telltale as to what you’re looking at.
Physically, the device fits in the palm of your hand. There’s no focusing lenses or frills on this device, it’s as basic as you can get and still have an operational device that’s not just exposed circuitry.
The front with screen.
The side, showing the USB port and the open frame construction.
The back of the unit with the business end of the device.
Overall? This is a pretty amazing tool for $40. It’s not going to show you detailed images of something, but it’s just enough that you could spot a hotspot on a board or piece of equipment, helping you pinpoint things for further troubleshooting.
Beyond that? It’s just a cool toy and an amazing piece of tech.
- 2023
- Sep
- 17
A Supercapacitor UPS? Does it work?
I picked up a couple of cheap ($25ish) Supercapacitor UPS devices from AliExpress. I wasn’t sure what to expect from them, but they work surprisingly well. This is a true UPS, and stores enough power to shut your device down gracefully - not hold it up for hours.
I’m doing some testing and will post my results in a few weeks. Stay tuned!
- 2023
- Jul
- 10
Random board shot: The Atari 2600
This is an Atari 2600 “Video Computer System,” or VCS:
But you knew that already. This is the model known as the “Heavy Six.” It was made in Sunnyvale, California.
It’s a first generation model. It’s called a Heavy Six because of the six switches on the front panel, and it weighed more than later models due to the thick cabinet:
And because of the cast aluminum RF shield present around the actual processor and other circuitry. This was not present in later models:
The cabinet is held together with 8 screws, and splits easily into two halves.
Code named “Stella” when it was being developed, one of the removed features was built-in speakers. You can still see the holes in the top chassis where they were supposed to be mounted.
But that’s not what interests me the most. If you examine the board, you’ll notice that now familiar Textolite “T” imprinted in the circuit board itself, indicating the raw board came from the GE plant in Coshocton, OH.
It still amazes me how far-reaching this little town’s products were.
- 2023
- Jun
- 27
Checking out an Eico 145 Signal Tracer
This is an Eico 145 Signal Tracer that I picked up at the Breezeshooters’ Hamfest in Butler, PA. I didn’t really need it, but the gentleman that was selling it only had a few bucks on it, so why not? This is basically a test amplifier, replacement speaker, and a replacement output transformer for troubleshooting radio and other basic consumer electronics from the vacuum tube era.
Tube compliment is:
6X5 dual diode rectifier
6SJ7 pentode as the audio preamp
6K6 pentode as the audio power amp
All the tubes for this device are octal. Later models used miniature tubes.
The unit has multiple manufacturers present in the tube lineup, so this thing probably saw a fair bit of use during it’s day. Counterclockwise from the left, it’s GE, RCA, and Sylvania, although the RCA and Sylvania tubes both exhibit the octagonal tube number symbol that indicate they were made by RCA. You can’t trust the label on these things, every manufacturer made things for every other manufacturer!
The front panel is in well-used condition, with a spray of bronze paint across the top. Was someone trying to repaint another piece of Eico gear with that sandalwood-bronze paint they liked to use?
The top is rusty-ish, more so that the rest of the chassis. Perhaps it was someplace damp enough that water condensed on the top due to temperature differentials? Who knows. The handle is in excellent condition, and present - always a plus for these units.
Chassis isn’t in too bad of condition, although there are definite signs of repairs and modifications along the way, especially the jack that’s been added to the front to allow a later model signal tracer’s RF probe to be used with this device.
The bottom of the unit was in acceptable condition. This unit was most likely built by the end user. It’s put together in a decent manner, but is a bit of routing and soldering here and there that reveal it was built by a non-professional. That’s not an issue, it’s worked this long. (You could buy these pre-built by the factory or you could do it yourself.)
There were some parts just floating around in the chassis, including two wax capacitors for the input. These just went up through the chassis and connected to repaired wires near the function selection switch. They may be original, but have been touched at some point in their life. Note also the across-the-line capacitor (800V 0.05uF) and the added jack for the later RF probe.
There was some burnt insulation suggesting a soldering iron had been a little careless over the years. That needs to be replaced or covered at some point, but since that’s part of the electrolytic assembly it will probably just get replaced. The electrolytic itself appears to be a replacement, as the soldering job is different (and messier) than the other joints.
One I noted here was the black cloth-coated wire running up to the top of the tube socket. This has a cold joint with enough mechanical connection to make it work. How long has this been like it is? Probably since it was built. That needs to be cleaned up and fixed if this device is ever going into use.
Since there’s no obvious shorts, and a quick check of the capacitors didn’t reveal anything unusual, I decided to give it the ‘ol Brute Force Reform, aka just plug it in (to a fused socket of course!) After a bit of warmup, I have light!
There’s no hum or excessive noise, so the device is still functional. I applied a 1KHz signal to the input, set it to Trace, and yep. It works fine. Sounds just a bit ragged, so there may be something wrong, or perhaps my cheap well used signal generator needs some work. But everything important here is operational, tubes, transformers, switches. The rest can be replaced if need be.
This gets buttoned up and is now awaiting a few minor replacements before going into use as-is. Nothing like a battle-scarred piece of equipment on your desk!
Next part of this series: https://wereboar.com … ignal-tracer-part-0/
- 2023
- Jun
- 10
Dayton purchase: An HP3440 NIXIE DVM
One of the things I keep an eye out for is NIXIE equipment. I have a few pieces in service, and as these devices age they are getting harder to find. People such as myself buy them for parts and spares, and godless heathens destroy them for the tubes so as to build clocks. It’s not uncommon to find an empty chassis where all the boards were discarded when the tubes were removed.
Fortunately, this wasn’t one of those. Cosmetically, it was in ok shape. Covers were all present, feet and bail were there, it looked it’s age. Wood screws holding the bottom cover on suggested someone had been in it and lost parts, so that was taken into account. The vendor said that it worked, but examination and experience said it probably didn’t. I was right.
The aforementioned screws told a story that someone had probably opened it, let it set, and someone else hastily tied it up for sale. It had several non-factory features installed, including both the clogged-with-mud input terminals, and the rust-onna-nut package for the plug-in module. This thing probably sat in a barn or garage for a while.
As Shango066 says, the first thing you do is look at the device thoroughly to note anything unusual. The inside had several things to see. The device had about the level of dirt I’d expect, although it’s not really that old for one of these units. Date codes on capacitors suggested this had been made (or repaired) at some point in the early 80s. That it didn’t have ICs for the driver cards suggests it’s not one of the last ones, but it’s getting close.
The first thing of note was the missing fuse at the top of the device. This wasn’t as much of a concern as you’d think, as it fed the recorder output instead of being a fuse for one of the power supplies.
The plugin module had some interesting things going on as well. One of the cards was not seated properly in it’s slot - this could be from vibration or other mechanical stress, so that was simply a matter of pulling it out and re-seating it properly. The card was slightly warped, so it had been like that for some time.
The most interesting thing here was the two orange dry electrolytics in the middle of the module. This most certainly isn’t factory, and as they were just hanging loose and kind of tied together. It’s pretty obvious this isn’t a factory part - if you hadn’t guessed that already.
I don’t know that you could get that style of capacitor in the 80s, so those may have been hanging around in someone’s parts bin, or may have even been rescued from an old television set before making their way into this device. If I plan on putting this module into service in one of my other devices, it will need to be repaired correctly.
Note the ultra-precision resistors present in this module. 10.114k (!)
The bottom wasn’t as bad, but still showed some work.
There was some dirt along the wires indicating it had been in use for quite some time, and one of the clamps was broken. I’m not sure if this was due to age or someone moving wires frequently, but it’s not that big of an issue. The big takeaway here is the rat’s nest in the upper left hand corner of the unit. The string ties had all been removed and this bundle had been poked at numerous times. Nothing was broken or showed signs of insulation damage, so I ignored it and moved on.
So…what’s actually wrong with this unit? As you can see from the first picture, almost all of the tubes light up. The second numeric tube has some bad segments, but that’s to be expected. This unit simply didn’t DVM. Normally, the neon lamp to the left will flash, one flash per read. This one did not, it was like it was in hold mode. You could mess with the 8000 button, and the sample rate control to get it to manually change, but it was not performing those reads automatically like it should.
Often times, that will be because the cards are in need of an edge cleaning, so I decided to do that. You simply pull the card, clean the fingers with a pencil eraser, make sure it free of debris, and re-insert. I have to do this to most of my units once a year or so.
This is the power supply card. Notice that there’s been a lot of repair to the unit, as evidenced by the flux-coated joints. This is not how HP would have left anything from the factory. There’s also a bit of corrosion on some of the larger joints, as evidenced by the darkened solder. This has been exposed to some dampness at some point in it’s life.
The fingers weren’t that bad, normally they exhibit marks where they’ve been placed and removed multiple times. This may have just been out a few times. Power supply is operational, so nothing to do here other than clean and replace.
This is one of the NIXIE driver cards. The fingers on this didn’t indicate any removal, and none of these cards showed any repairs.
How does this work? These are an up-counter with a wheatstone bridge. One of the bridge sides is a ramp voltage, another side is the unknown input. The ramp voltage increases and the cards count up, when the bridge becomes balanced the unit stops counting and displays the unknown input on the tubes. Of particular note is how HP decoded the output - the black “socket” for the tube contains a photoconductive plate with neon bulbs driven by the flip-flops on the card. Depending on what sequence of bulbs is lit, certain parts of the photoconductive plate are active and drive the segments of the display tube. It’s fascinating how they did that and is worth a paper of it’s own. Maybe for a future post?
Here’s the card that’s most likely the problem. The ramp generator. It had marks on the fingers indicating this had been in and out of it’s socket many times. It, for some reason, also had a lot of bug debris on it. Only this card hard that, so I wonder if this was pulled from another unit originally - usually when insects get into a device like this, their crap is all over the thing.
If you look closely, Q8 right in the middle of the card has been lifted as if someone was troubleshooting the device before I got it. So this is indeed the problem (probably!) and if I wanted to fix the device, I’d start here.
But, that’s the thing. I bought this knowing that it probably didn’t work due to the condition of the unit. It was purchased solely for parts, and parts it is. I’m not sure how much time I want to spend on this, but who knows. I may have a spare ramp card in my box ‘o junk, as I’ve purchased these units before in tear-down condition. I might wait until the snow flies and dig that box of cards out of storage and see what’s in there.
Until then, this unit is going to serve it’s function of being a parts donor for my other units.
Stay tuned, next week there’s one more show’s worth of pictures to post until late summer. The Butler Breezeshooter’s hamfest was a nice show, and I brought home stuff I didn’t need. As usual!
- 2023
- Jun
- 3
Dayton 2023: Stuff I drug home.
I made good on my promise to not drag home too much junk this year, but a few boat anchors did manage to make their way in my car. Both of them had an immediate use, but the one that was going to go in to the rack didn’t work. Not a big deal, but still…it gives me a change to re-engineer some stuff. The rest of the items were parts for later use, whenever the need arises.
Just some random bits I picked up. An old LED display (made in the USA!) from Rat Shack, and a 1971 Allied/Radio Shack catalog. The catalog is fascinating, the prices that some of the things cost was incredible, and it’s interesting seeing some of the Shack’s staples like the Weather Cube. It’s fun to look through it and see things I wish I could still buy.
A vendor was selling older Jim-Pak parts, as well as a handful of things from other vendors. Some were $1 per, others were 2 or 4 per $1. I picked a selection of parts, as well as some of those oddball fuses old meters used for their current sections.
This is a unit that was meant to monitor the audio feeds in a studio. At it’s heart, it’s two “channels” with a center channel. Unfortunately, it didn’t work. Examination reveals a lot of white corrosion on the input board, and it looks like some water was spilled and lay on the board for a long period of time. That’s not really a big deal, I’m thinking a couple of LM386 ICs can fix this guy right up. I’m not interested in studio accuracy, I want something for my rack that I can connect to the plugboard for audio testing.
According to the vendor, this works. Well…it didn’t. Mostly. I picked it up for parts since many of these are being torn down for the displays so they can become clocks. :( The device itself had a hard life, evidenced by the replacement screws in the bottom and the considerable cosmetic damage to the unit itself. It had all of it’s feet and bail, so that’s quite nice.
An examination on the inside revealed many repairs, some boards that had left their slots, and a missing fuse. Bringing the device up on power revealed that it indeed did not work, the master clock was not present so the device wouldn’t sample. One of the tubes was also partially bad, but it had the incredibly rare polarity indicating tube, probably worth the price of the device itself.
While cleaning the card edges I found that the clock card had a transistor leg lifted, so someone was troubleshooting the device when it was put aside. As this was supposed to be a parts unit, I’m not sure how far I want to go fixing it - if at all - but it will be the subject of a future post detailing the examination.
This is one of Radio Shack’s oddball devices from the CB radio era. It’s a crystal-controlled device that listens to Channel 9, which was commonly used as the emergency channel It was designed for antenna passthrough, and has it’s own speaker. If I can find a schematic for this, I may see if I can re-tune it to Channel 19, since there’s still a little activity there.
A friend of mine said he wanted a 2-pin cable for a battery box project he made. Said he needed an extension, so I found this. It’s not going to get warm anytime soon.
This was a CB-era piece in the bins with the Jim-Pack parts. I don’t know why I got this other than it’s funny. Rip-off characters, anyone?
The slim haul wasn’t because I didn’t see things I wanted. I did. A lot of it. There were a couple of pieces that I saw that I wanted to bring home, but didn’t have a need for - a WWV receiver and some other devices among them. I figured if they were there Sunday, I’d bargain, but they weren’t. That’s me being told that I don’t need them, leave them where you found them.
(But you know very well if i see that receiver again I may pick it up because I’m being told it’s still here so you know you want it!)
Overall, I think I got some good stuff. The meter may make an interesting project, should I decide to repair it, but I think it’s just parts with a good plug-in for my other devices.
Next show is Butler, PA, and then nothing for a few month. Stay tuned for some show posts from that one, and some detail posts on a few of the devices I’ve picked up over the last year.