Signal Injector Might Still Be Handy

July 26, 2025 by Al Williams 1 Comment

Repairing radios was easier when radios were simple. There were typically two strategies. You could use a signal tracer (an amplifier) to listen at the volume control. If you heard something, the problem was after the volume control. If you didn’t, then the problem was something earlier in the signal path. Then you find a point halfway again, and probe again. No signal tracer? You can also inject a signal. If you hear it, the problem is before the volume. If not, it is after. But where do you get the signal to inject? [Learn Electronics Repair] sets out to make a small one in a recent video you can see below.

Both signal tracers and injectors were once ubiquitous pieces of equipment when better options were expensive. However, these days, you can substitute an oscilloscope for a signal tracer and a signal generator for an injector. Still, it is a fun project, and a small dedicated instrument can be handy if you repair a lot of radios.

The origin of this project was from an earlier signal injector design and a bet with a friend about making a small version. They are both working on their designs and want people to submit their own designs for a little ad hoc contest.

We always preferred a signal tracer since it is more passive. Those were typically just audio amplifiers with an optional diode in the input to demodulate RF. A computer amplified speaker and a diode can do the job, as can an LM386. Or, you can build something complex, if you prefer.

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Read QR Codes On The Cheap

July 26, 2025 by Al Williams 15 Comments

Adding a camera to a project used to be a chore, but modern camera modules make it simple. But what if you want to read QR codes? [James Bowman] noticed a $7 module that claims to read QR codes so he decided to try one out.

The module seems well thought out. There’s a camera, of course. A Qwiic connector makes hooking up easy. An LED blinks blue when you have power and green when a QR code shows up.

Reading a QR code was simple in Python using the I2CDriver library. There are two possible problems: first, if the QR code contains a large amount of data, you may exceed the I2C limit of 254 bytes. Second, despite claiming a 110-degree field of view, [James’] testing showed the QR code has to be almost dead center of the camera for the system to work.

What really interested us, though, was the fact that the device is simply a camera with an RP2040 and little else. For $7, we might grab one to use as a platform for other imaging projects. Or maybe we will read some QR codes. We’d better pick up a few. Then again, maybe we can just do it by hand.

Hackaday Podcast Episode 330: Hover Turtles, Dull Designs, And K’nex Computers

July 25, 2025 by Al Williams 1 Comment

What did you miss on Hackaday last week? Hackaday’s Elliot Williams and Al Williams are ready to catch you up on this week’s podcast. First, though, the guys go off on vibe coding and talk about a daring space repair around Jupiter.

Then it is off to the hacks, including paste extruding egg shells, bespoke multimeters, and an 8-bit mechanical computer made from a construction toy set.

For can’t miss articles, you’ll hear about boring industrial design in modern cell phones and a deep dive into how fresh fruit makes it to your table in the middle of the winter.

Check out the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

The DRM-free MP3 was stored in a public refrigerated warehouse to ensure freshness. Why not download it and add it to your collection?

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Not Repairing An Old Tape Recorder

July 24, 2025 by Al Williams 13 Comments

When you think of a tape recorder, you might think of a cassette tape. However, [Michael Simpson] has an old Star-Lite small reel-to-reel tape machine. It isn’t a repair so much as a rework to make it work better. These cheap machines were never the best, although a $19 tape player back then was a luxury.

Part of the problem is that the design of the tape player wasn’t all that good to begin with. The motor runs off two C cells in parallel. When these were new in the 1960s, that would have meant conventional carbon-zinc batteries, so the voltage would have varied wildly. That didn’t matter, though, because the drive was directly to the tape reel, so the speed also varied based on how much tape was left on the reel.

The amplifier has four transistors. [Michael] decided to replace the capacitors on the unit. He noticed, too, that the volume control is in line with the microphone when recording, so even though the recording was supposedly in need of repair, it turned out to be simply a case of the volume control being turned down. Pretty impressive for a six-decade-old piece of consumer electronics.

The capacitor change-out was simple enough. Some cleaning and lubing was also in order. Did it help? You’ll have to listen and decide for yourself.

So, no real repair was in the works, but it is an interesting look back at an iconic piece of consumer tech. Tape recorders like this were an early form of social media. No kidding. If you’d rather not buy a tape recorder, you could roll your own.

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This SSD Will Self Destruct In Ten Seconds…

July 16, 2025 by Al Williams 16 Comments

In case you can’t wait for your flash memory to die from write cycling, TeamGroup now has a drive that, via software or hardware, can destroy its own flash chips with a surge of voltage. If you wonder why you might want this, there are military applications where how you destroy a piece of equipment is right up there in the manual with how to use it.

They have obviously put a lot of thought into it, as you can see in the video below. Apparently, if you are in the middle of blowing up the flash and power cuts out, the chip will resume frying itself when you restore power.

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The DEW Line Remembered

July 16, 2025 by Al Williams 20 Comments

The DEW line was one of three radar early warning systems of the time.

If you grew up in the middle of the Cold War, you probably remember hearing about the Distant Early Warning line between duck-and-cover drills. The United States and Canada built the DEW line radar stations throughout the Arctic to detect potential attacks from the other side of the globe.

MIT’s Lincoln Lab proposed the DEW Line in 1952, and the plan was ambitious. In order to spot bombers crossing over the Arctic circle in time, it required radar twice as powerful as the best radar of the day. It also needed communications systems that were 99 percent reliable, even in the face of terrestrial and solar weather.

In the end, there were 33 stations built from Alaska to Greenland in an astonishing 32 months. Keep in mind that these stations were located in a very inhospitable environment, where temperatures reached down to -60 °F (-51 °C). Operators kept the stations running 24/7 for 36 years, from 1957 to 1993.

System of Systems

The DEW line wasn’t the only radar early-warning system that the US and Canada had in place, only the most ambitious. The Pinetree Line was first activated in 1951. However, its simple radar was prone to jamming and couldn’t pick up things close to the ground. It was also too close to main cities along the border to offer them much protection. Even so, the 33 major stations, along with six smaller stations, did better than expected. Continue reading “The DEW Line Remembered” →

A History Of The Tandy Computers

July 15, 2025 by Al Williams 22 Comments

Radio Shack, despite being gone for a number of years, is still in our cultural consciousness. But do you know Tandy? And did you ever wonder how a leather company that started in 1919 became, briefly, a computer giant? Or even an electronics retailer? [Abort Retry Fail] has the story in three parts, framed with their computers. Well, three parts so far. They are only up to the Tandy 1000.

At first, the company made parts for shoes. But after World War II, they found that catering to leather crafting hobbyists was lucrative. Within a few years, they’d opened stores across the country, making sure that the store managers owned 25% of their stores, even if it meant they had to borrow money from the home office to do so. Meanwhile, Radio Shack was in Boston selling to radio amateurs. By 1935, Radio Shack was a corporation. In 1954, they started selling “Realist” brand equipment, that we would come to know as Realistic.

In 1961, Tandy decided to branch out into other hobby markets, including radio hobbyists. But Radio Shack, dabbling in consumer credit, was sunk with $800,000 of uncollectable consumer credit.

In 1963, Tandy purchased the struggling Radio Shack for $300,000, which was a substantial amount of money in those days. Tandy immediately set about making Radio Shack profitable. Tandy would eventually split into three companies, spinning off its original leather and craft businesses.

Then came computers. If you are at all interested in the history of early computers, the TRS-80, or any of the other Radio Shack computers, you’ll enjoy the story. It wasn’t all smooth sailing. We can’t wait to read part four, although sadly, we know how the story ends.

We don’t just miss the Radio Shack computers. We loved P-Box kits. Yeah, we know someone bought the brand. But if you visit the site, you’ll see it just isn’t the same.