A Relay Calculator With DIY Neon Displays, Just Because

March 8, 2018 by Dan Maloney 3 Comments

This looks like one of those projects that started out as a glimmer of an idea and led down a rabbit hole. But it’s a pretty cool rabbit hole that leads to homebrew neon seven-segment displays on a calculator with relay logic.

It’s a little thin on documentation so far, but that’s because [Mark Miller]’s build is one of those just-for-the-fun-of-it things. He started with a bag full of NE-2 tubes and the realization that a 3D-printed frame would let him create his own seven-segment displays. The frames have a slot for each segment, with a lamp and current limiting resistor tucked behind it; with leads brought out to pins and some epoxy potting, these displays would be hard to tell from a large LED seven-segment. Rolling your own displays has the benefit of being able to extend the character set, which [Mark] did with plus-minus and equal sign modules. All of these went together into a two-banger calculator — addition and subtraction only so far — executed in relays and vacuum tubes. Version 2.0 of the calculator regressed to all-relay logic, which must sound great.

We heartily regret the lack of a satisfyingly clicky video, but we’ll give it a pass since this is so cool. We’ll be watching for more on this project, but in the meantime, if you still need to get your click on, this electromechanical BCD counter should help.

Hijacking A Sony Watchman For Pong

March 7, 2018 by Inderpreet Singh 11 Comments

The era of the vintage television was a great one, and one of the transitional by-products was the Sony Watchman. It was a portable TV which Sony started selling in 1982, and the amazing thing about it was that it had an actual 4-inch cathode ray tube or CRT. [Sideburn] just posted a video in which he hijacks the internals of a Watchman to make it into a portable game of Pong.

The hack begins with removing the TV tuner module inside to make some room for the new residents. Next comes the M51364P which is VIF video decoder chip, and for which surprisingly there is not a lot of info on the web. They were able to find a part of the schematic, which though it was in Russian may still be useful for enthusiasts. Removing the VIF revealed the audio and video pins that needed the appropriate signals for the hack to be successful. In an age of multilayer boards it is amazing how a two-layer PCB makes life so easier for the tinkerer.

For the new brains an Arduino Nano clone was selected, and instead of adding modern buttons the existing volume and band select switches were convinced to be the paddle control and play/pause button. Getting everything to fit was easy with the absence of the tuner module, and voila! New(ish) hardware. For the firmware, [Sideburn] turns to Hackvision firmware which has a host of games such as Space Invaders, Asteroids, and even Tetris.

We covered Hackvision a few years ago as a hardware/firmware bundle, and if you are more into CRTs then check out the Arduino driven 6845 CRT controller.

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An Old Way To Make A New Crank Handle

March 3, 2018 by Kristina Panos 24 Comments

When the crank handle on [Eric Strebel]’s cheapo drill press broke in two, did he design and print a replacement? Nah. He kicked it old school and cast a new one in urethane resin.

In his newest video, [Eric] shows us his approach to molding and casting a handle that’s likely stronger than the original. The old crank handle attached to the shaft with a brass collar and a grub screw, so he planned around their reuse. After gluing the two pieces together and smoothing the joint with body filler, he packs the back of the handle with clay. This is a great idea. The original handle just has hollow ribbing, which is probably why it broke in the first place. It also simplifies the cast a great deal.

Here’s where things get really interesting. [Eric] planned to make a one-piece mold instead of two halves. At this point it becomes injection molding, so before he gets out the reusable molding box, he adds an injection sprue as an entry point for the resin, and a plug to support the sprue and the handle. Finally, [Eric] mixes up some nice bright Chevy orange resin and casts the new handle. A few hours later, he was back to drilling.

Crank past the break to watch [Eric]’s process, because it’s pretty fun to watch the resin rise in the clear silicone mold. If you want to take a deeper dive into injection molding, we can fill that need.

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Investigating The World’s Rarest Game Boy

February 27, 2018 by Tom Nardi 20 Comments

Early last year, a very unique Game Boy Color showed up on Chinese shopping site Taobao. Rather than the rather anemic-looking display of the original GBC, this version was modified with a modern IPS LCD. Even in the pictures shown on the product page, it was clear the display on this unit was far more advanced than anything Nintendo ever packed into a Game Boy. The retro gaming community went wild, and soon the site was overwhelmed with orders. The majority of the sales were canceled by the seller, and it’s believed as few as 75 of these hacked GBCs were actually shipped out.

Thanks to one of his viewers, [Colin] was able to get his hands on one of these extremely rare customized handhelds. Clearly a man after our own heart, his first inclination was to tear the thing apart and see how they built it. While he had a fairly good idea of how they managed this hybrid of modern and classic technology, there were a couple of surprises inside.

The device has a completely stock main board, and as such works and plays like a normal GBC. But upon flipping the main board over, [Colin] found a nest of thin magnet wire connecting the new display controller to individual buttons on the front panel. As he later confirmed when he reassembled the system, this allows the user to adjust the display’s brightness by holding “Select” and using the directional pad.

As for the screen itself, the big surprise was that it’s clearly pulled out of a relatively recent smartphone. The screen is physically much larger than the opening in the GBC’s front panel, but through some software trickery the image is displayed only in the area that’s visible to the player. [Colin] managed to get a hold of a few contacts “in the know” who confirmed to him that both the hardware and software for the display controller were specifically created for this application, and are unlikely to be duplicated by anyone else.

Considering most of the Game Boy hacks we cover are about somebody jamming modern hardware into them, it’s an interesting change of pace to see a group that was so adamant about retaining as much original hardware as possible while still managing to improve the user experience.

[Thanks to Doc Oct for the tip]

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PC-XT Emulator On ESP8266

February 26, 2018 by Steven Dufresne 58 Comments

Do you remember the simpler times when you had a DOS command line, a handful of commands, and you talked to the hardware through a few BIOS and DOS interrupts? Okay, maybe it was a little limited, but nostalgia doesn’t care. Now [mcuhacker] is working on bringing some of those memories back by getting a PC-XT emulator running on an ESP8266.

For the x86 CPU emulator, he ported Fake86 which is written in C, and created an Arduino IDE environment for it. The MS-DOS 3.3 bootdisk image is stored in flash and is accessed as the A: drive. There’s no keyboard yet but he has 640×200 CGA working with 80×25 characters on a 3.5″ TFT display with the help of a low pass filter circuit. In the video below he shows it booting to the point where it asks for the date.

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QuickBASIC Lives On With QB64

February 22, 2018 by Tom Nardi 190 Comments

When I got my first computer, a second hand 386 running MS-DOS 6.22, I didn’t have an Internet connection. But I did have QuickBASIC installed and a stack of programming magazines the local library was throwing out, so I had plenty to keep myself busy. At the time, I thought QuickBASIC was more or less indistinguishable from magic. I could write simple code and compile it into an .exe, put it on a floppy, and give it to somebody else to run on their own machine. It seemed too good to be true, how could this technology possibly be improved upon?

Of course, that was many years ago, and things are very different now. The programming languages du jour are worlds more capable than the plodding BASIC variants of the 80’s and 90’s. But still, when I found a floppy full of programs I wrote decades ago, I couldn’t help but wonder about getting them running again. With something like DOSBox I reasoned I should be able to install the QuickBASIC IDE and run them like I was back on my trusty 386.

Unfortunately, that was not to be. Maybe I’m just not well versed enough in DOSBox, but I couldn’t get the IDE to actually run any of the source code I pulled off the floppy. This was disappointing, but then it occured to me that modern BASIC interpreters are probably being developed in some corner of the Internet, and perhaps I could find a way to run my nearly 30 year old code without having to rely on 30 year old software to do it. Continue reading “QuickBASIC Lives On With QB64” →

Relive Radio Shack’s Glory Days By Getting Goofy

February 21, 2018 by Dan Maloney 32 Comments

The Golden Age of Radio Shack was probably sometime in the mid-1970s, a time when you could just pop into the local store and pay 49 cents for the resistors you needed to complete a project. Radio Shack was the place to go for everything from hi-fi systems to CB radios, and for many of us, being inside one was very much a kid in a candy store scenario.

That’s not to say that Radio Shack was perfect, but one thing it did very well was the education and grooming of the next generation of electronics hobbyists, primarily through their “Science Fair” brand. Some of us will recall the P-Box kits from that line, complete projects with all the parts and instructions in a plastic box with a perfboard top. These kits were endlessly entertaining and educational, and now [NetZener] has recreated the classic neon “Goofy Light” P-Box project.

As it was back in the day, the Goofy Light is almost entirely useless except for learning about DC-DC converters, multivibrators, RC timing circuits, and the weird world of negative resistance. But by using the original Science Fair instructions, compiling a BOM that can be filled from Mouser or Digikey, and making up a reasonable facsimile of the original P-Box chassis, [NetZener] has done a service to anyone looking for a little dose of nostalgia.

It would be interesting if someone brought back the P-Box experience as a commercial venture, offering a range of kits with circuits like the originals. If that happens, maybe some of the offerings will be based on that other classic from Radio Shack’s heyday.

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