Author: Al Williams

3639 Articles

Early CD Player Teardown

April 18, 2024 by 16 Comments

While CD players are nothing new today, they were the height of high-tech in the early 1980s. [w1ngsfly] shows us the inside of a Phase Linear 9500 player from 1983. Not only does it have many components, but it is also mechanically unusual.

The CD loads into a toaster-like slot and even pops out like a piece of toast. The tracking mechanism is quite complex, and there’s something that looks suspiciously like a dial string from an old slide rule tuner radio. Apparently, the unit was made by Kyocera and is internally similar to a Kyocera DA-01.

There’s a “head position” indicator that is actually just an LED connected to the tracking mechanism. The front panel controls look great but also allow you to control the head position exactly. As [w1ngsfly] mentions, it is almost like moving a turntable’s tonearm where you can drop it anywhere you want.

If we recall, they were about $600 to $1,000 new. If Phase Linear doesn’t ring a bell, they were well known in their day. Founded by [Bob Carver] and [Steve Johnston], the company was bought by Pioneer before the introduction and, later, by Jensen before the introduction of the 9500. [Bob] would go on to found Carver Corporation. You can find plenty of history about the company online.

We’ve seen CD players that look older. These days, CD drives are cheap and they are easy enough to control.

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Getting Started With Radio Astronomy

April 17, 2024 by 10 Comments

There are many facets to being a radio hobbyist, but if you’ve ever had the urge to dabble in radio astronomy, check out “The Novice’s Guide to Amateur Radio Astronomy,” a presentation at the 2024 conference of the Society of Amateur Radio Astronomers. In that presentation (see the video below), [Nathan Butts] covers everything from why you should take up the hobby, how to set up a software defined radio (SDR) receiver, and how to repurpose old computers. This is just one of a series of videos recently posted from the conference — check out their channel to see them all.

Unlike optical astronomy, you can listen to the universe by radio during the day or night, rain or shine. You don’t need a dark sky, although these days, a quiet radio location might be hard to find. [Nathan] also points out that some people just want to crunch data collected by others, and that’s fun, too. There are many ways to get involved from designing hardware, writing software, or — of course — just listening.

It has never been easier to get involved. Cheap software-defined radios are perfect for this sort of work, and we all have massive computers and scores of small data-collection computers. Maybe you’ll be the next person to hear a Wow signal. If you are worried about fielding an antenna, many people repurpose satellite dishes.

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Recycling Wires For Breadboarding

April 16, 2024 by 36 Comments

It is easy to take things for granted, but if you work with students, you realize that even something as simple as a breadboard needs explanation. [0033mer] recently shared a tip about how he wires both solderless breadboards and prototype boards on the cheap. Instead of buying special wires, he salvages riser cables often found in scrap from demolished buildings. These often have 200 or so thin solid wires inside. You take them apart, and, as he put it, if you have 15 feet of the stuff, that will last you the rest of your life. We hope you live longer than that, but still.

One advantage to doing this is you don’t feel bad about cutting the wires exactly to length which makes for neat boards. He has a tiny stripper that make it easy to remove the insulation during installation.

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Linux Fu: Stupid Systemd Tricks

April 16, 2024 by 15 Comments

Last time, I gave a whirlwind introduction to a very small slice of systemd. If you aren’t comfortable with systemd services, timers, and mounts, you might want to read that now. Otherwise, press on to see a few interesting uses for custom systemd units, including running a few things on a schedule and automatically mounting a Raspberry Pi Zero.

Can you do every one of these things in a different way? Of course you can. I’m not debating the relative merits of using or not using systemd. However, unless you totally control your own environment, good chance you are going to have to interact with systemd at some point.

Stupid Trick #1: Update Your IP Address

A few years ago, I talked about updating your remote DNS server with your public IP address. This lets you refer to a hostname like snoopy.hackaday.com and get back to your computer that often changes IP addresses. Sure, you can get services to do that for you, but you must either pay or agree to read ads on their site to keep your hostname going. This is all under your control. In the original post, I suggested using cron or NetworkManager to run the update script. I also hinted you could do it with systemd, but I didn’t tell you how. Let’s fix that.

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Plasma Cutter On The Cheap Reviewed

April 15, 2024 by 24 Comments

If you have a well-equipped shop, it isn’t unusual to have a welder. Stick welders have become a commodity and even some that use shield gas are cheap if you don’t count buying the bottle of gas. But plasma cutters are still a bit pricey. Can you get one from China for under $300? Yes. Do you want one that cheap? [Metal Massacre Fab Shop] answers that question in the video below.

First impressions count, and having plasma misspelled on the unit (plasme) isn’t promising. The instructions were unclear, and some of the fittings didn’t make him happy, so he replaced them with some he had on hand. He also added some pipe tape to stop any leaking.

The first test was a piece of quarter-inch steel at 35 amps. The machine itself is rated to 50 amps. Sparks ensued, and with a little boost in amperage, it made a fair-looking cut. At 50 amps, it was time to try a thicker workpiece. It made the cut, although it wasn’t beautiful. The leaking regulator and the fact that he can’t run the compressor simultaneously as the cutter didn’t help.

From the look of it, for light duty, this would be workable with a little practice and maybe some new fittings. Unsurprisingly, it probably isn’t as capable as a professional unit. Still could be very handy to have.

It is possible to convert a welder into a plasma cutter. A handheld unit like this probably won’t benefit from a Sharpie.

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Waveform Generator Teardown Is Nearly Empty

April 15, 2024 by 26 Comments

We always enjoy [Kerry Wong]’s insightful teardowns, and recently, he opened up a UTG1042X arbitrary waveform generator. Getting inside was a bit of a challenge since there were no visible screws. Turns out, they were under some stickers. We always dislike that because it is very difficult to get the unit to go back together.

Once open, the case reveals it is almost completely empty. The back panel has a power supply, and the front panel has all the working circuitry. The box seems to be for holding the foot and preventing the device from getting lost on your bench.

The power supply is unremarkable. There are a few odd output voltages. The main board is a bit more interesting, especially after removing the heat sink. There are two channels, but the board isn’t laid out, with a lot of segregation between the two channels. That makes sense with the output sections clustered together and the digital section with the CPU, FPGA, and the DAC in close proximity.

The other side of the board connects to a very simple display board. It would be interesting to compare this to a circa-1980s AWG, which would have been far more complicated.

Making a waveform generator with a microprocessor and a DAC isn’t hard. The hard part is the output stages and maximizing the operating speed.

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Voice Control For A Vintage Heathkit Radio

April 14, 2024 by 6 Comments

Most modern ham rigs have a voice activated transmission (VOX) mode, although we don’t know many people who use it often. When a transmitter is in VOX mode, it starts transmitting when you talk, and then, when you pause for a second or two, the transmitter turns off. Many old ham transmitters, though, didn’t support VOX, so Heathkit sold the VX-1 “electronic voice control” to add VOX to older transmitters. [Jeff Tranter] shows us inside a clean-looking unit.

These devices were sold from 1958 to 1960 and used tubes and a selenium rectifier. The device is connected between the microphone and the transmitter. It also sat between the receiver and the speaker to mute audio while transmitting. The original unit had a screw terminal to connect to the outside world, and some of the screws had live line voltage on them. The unit [Jeff] examines is modified to have phono jacks along with a few other repairs.

The wiring looks like a tube radio. Tubes are above the chassis, and point-to-point wiring is underneath. There is also an unusual sealed selenium rectifier. [Jeff] shows how the device works using just a receiver. A few minor repairs were needed.

If you are interested in getting your ham license, most modern radios support VOX out of the box — no rhyme intended. We do, however, love that old Heathkit gear.

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