Day: March 8, 2023

Old TV To RGB

March 8, 2023 by 19 Comments

As CRT televisions have faded from use, it’s become important for retro gaming enthusiasts to get their hands on one for that authentic experience. Alongside that phenomenon has been a resurgence of some of the hacks we used to do to CRT TV sets back in the day, as [Adrian’s Digital Basement] shows us when he adds an RGB interface to a mid-1990s Sony Trinitron.

Those of us lucky enough to have lived in Europe at the time were used to TVs with SCART sockets by the mid-1990s so no longer needed to plumb in RGB signals, but it appears that Americans were still firmly in the composite age. The TV might have only had a composite input, but this hack depends on many the video processor chips of the era having RGB input pins. If your set has a mains-isolated power supply then these pins can be hooked up with relative ease.

In the case of this little Sony, the RGB lines were used by the integrated on-screen display. He takes us through the process of pulling out these lines and interfacing to them, and comes up with a 9-pin D connector with the same pinout as a Commodore monitor, wired to the chip through a simple RC network and a sync level divider. There’s also a switch that selects RGB or TV mode, driving the OSD blanking pin on the video processor.

We like this hack just as much as we did when we were applying it to late-80s British TV sets, and it’s a great way to make an old TV a lot more useful. You can see it in the video below the break, so get out there and find a late-model CRT TV to try it on while stocks last!

Unsurprisingly, this mod has turned up here a few times in the past.

Continue reading “Old TV To RGB” →

Bode Plot Un-Lecture

March 8, 2023 by 4 Comments

[Rolinychupetin] insists that his recent video is not a lecture but actually a “recitation” about Bode plots. That may be, but it is still worth a watch if you want to learn more about the topic. You can see the video below.

If you haven’t run into Bode plots before, they are simple plots of magnitude or phase vs. frequency, usually plotted on a log scale. Named after Bell Lab’s [Hendrik Wade Bode], they are useful for understanding filters or anything with a frequency response.

Continue reading “Bode Plot Un-Lecture” →

Stepper Killer Killer Killed, Repair Attempted

March 8, 2023 by 12 Comments

The low-cost servo motor in [Clough42]’s lathe’s electronic leadscrew bit the dust recently, and he did a great job documenting his repair attempts ( see video below the break ). When starting the project a few years ago, he studied a variety of candidate motors, including a ClearPath servo motor from Teknic’s “Stepper Killer” family. While that motor was well suited, [Clough42] picked a significantly lower-cost servo motor from China which he dubbed the “Stepper Killer Killer”.

He does a very thorough post-mortem of the motor’s integrated servo controller, checking the circuits and connections on the interface PCB first. Not finding any obvious problem, he proceeds to the main PCB which contains the microcontroller, motor driver transistors, and power supplies. There is no visible damage, but a check of the logic power supply shows 1.65V where 3.3V is expected. Looking at the board with a smart-phone mounted IR camera, he quickly finds the bad news — the microcontroller has shorted out.

Continue reading “Stepper Killer Killer Killed, Repair Attempted” →

Scratch Built Amiga 2000 Stacks Up The Mods

March 8, 2023 by 8 Comments

Around these parts, we most often associate [Drygol] with his incredible ability to bring damaged or even destroyed vintage computers back to life with a seemingly endless bag of repair and restoration techniques. But this time around, at the request of fellow retro aficionado [MrTrinsic], he was given a special assignment — to not only build a new Amiga 2000 from scratch, but to pack it with so many mods that just physically fitting them into the case would be a challenge in itself.

The final product, dubbed Tesseract, took two and a half years to complete and has been documented over the course of six blog posts. The first step was to get a brand new motherboard, in this case a modern recreation designed by Floppie209, and start populating it with components. With some modifications, the new board slipped neatly into a slick metal case. Unfortunately it quickly became clear some of the mods the duo wanted to install wouldn’t work with the reverse-engineered motherboard. This was around Spring of 2021, which is the last time we checked in on the project. Continue reading “Scratch Built Amiga 2000 Stacks Up The Mods” →

Pi Picos Give Casio FX9000P Its Memory Back

March 8, 2023 by 12 Comments

Is the Casio FX9000P a calculator or a computer? It’s hard to tell since Casio did make calculators that would run BASIC. [Menadue] didn’t know either, but since it had a CRT, a Z80, and memory modules, we think computer is a better moniker.

He found one of these, but as you might expect, it needed a bit of work. There were two bad video RAM chips on the device, and [Menadue] used two Raspberry Pi Picos running a program to make them think they are RAM chips. The number of wires connecting the microcontollers might raise some eyebrows, but it does appear to get the job done.

He also used more Picos to emulate memory on cartridges. Then he used a test clip and a — you guessed it — another Pico to monitor the Z80 bus signals. It is amazing that the Pico can replace what would have been state-of-the-art memory chips and a very expensive logic analyzer.

The second video mostly shows the computer in operation. The use of Picos to stand in for so much is clever. It reminded us of the minimal Z80 computer that used an Arduino for support chips. The computer itself, though, reminded us more of a cheap version of the HP9845.

Continue reading “Pi Picos Give Casio FX9000P Its Memory Back” →

Supercon 2022: Alec Vercruysse Can See Through Murky Water

March 8, 2023 by 4 Comments

Detecting objects underwater isn’t an easy challenge, especially when things get murky and dark. Radio waves don’t propagate well, so most techniques rely on sound. Sonar is itself farily simple, simply send out a ping and listen for an echo, and that will tell you how far something is. Imaging underwater is significantly harder, because you would additionally need to know where each echo is coming from.

To answer the question of whether it is possible to put together an ultrasonic 3D imager that would cheaply enable anyone to image objects underwater, [Alec Vercruysse] and fellow team members at the Harvey Mudd College set out to create a system that does exactly that. You can read the presentation slides (PDF) or check out the entire project in the GitHub repository.

Continue reading “Supercon 2022: Alec Vercruysse Can See Through Murky Water” →

How To Make A Larger Air-Cored Inductor

March 8, 2023 by 20 Comments

Radio amateurs often have a love-hate relationship with home-made inductors, sharing all kinds of tips and tricks as to how the most stable nanohenry inductor can be wound. But there’s another group in the world of electronics with an interest in high-quality inductors, namely the audio enthusiasts. They need good quality inductors with a values in the millihenries, to use in loudspeaker crossover networks. [Homemade Audio] takes us through their manufacturing process for these coils, and the result is a watchable video resulting in some very well-made components.

The adjustable former is a machined aluminium affair of which we’re treated to the full manufacture. It’s likely the same results could be achieved with a 3D printed reel. The free-as-in-beer Coil64 on Windows is used to calculate the dimensions and number of turns, and it’s set up on a jig with a cordless screwdriver doing the winding. The best technique for flat layers of turns is explained, and a coat of varnish is put on each completed layer. We’re guessing this is to stop the coil “singing” at audio frequencies.

With a set of cable ties holding it together the result is a very tidy component. It’s adjusted a few turns to get the right value with an LCR meter, however experience tells us that a tiny percentage either way won’t harm the resulting network too much. If you make your own speakers, the video below the break could be extremely useful.

Need a loudspeaker primer? We have just the article for you.

Continue reading “How To Make A Larger Air-Cored Inductor” →