Pi-powered Atari 5200 multi-ROM cartridge (MultiCart)


Dr. Scott M. Baker has a nice write-up about building a multi-ROM cartridge for his Atari 5200 using Raspberry Pi:

The Atari 5200 is a vintage gaming system from the early 1980s. At the time I owned a 2600, but I always wanted a 5200. Well, in 2018 I finally decided to find one on eBay and buy it. I learned that the first thing you want to do after attaining a new gaming console is to get your hands on every available game cartridge for it, so I made this multi-ROM cartridge.
A multi-ROM cartridge, or “MultiCart” is a cartridge that contains more than one ROM image. There are multiple ways to go about this from selector switches to pick the cartridge you want, to built-in in game menu systems. I decided to go the route of using a Raspberry Pi for the user interface, making a WEB UI available to pick which cartridge is used.
The goal is not simply to play retro games on modern hardware — there’s any number of emulation solutions for that. The goal is to play retro games on retro hardware, but use a modern system to load the game image into the console.

See the full post at smbaker.com and the GitHub repository here.

Check out the video after the break.

Multichannel logic probe and pulsar


Dilshan Jayakody published a new build:

This is 8 channel CMOS logic probe and pulsar which is useful when designing, testing and faultfinding in digital circuits. This circuit is designed using commonly available CMOS logic ICs which including couple of 4069 hex inverters and 4040 binary counter.
Logic probe of this system is based on 4069 hex inverters and it indicate logic high and low states with 2 LEDs. Logic pulsar of this circuit is capable to generate 12 frequencies and highest frequency it can generate is 420kHz. This pulsar generate square wave with 50% duty cycle and it’s average raise time is 16µS.

See the full post on Dilshan Jayakody’s blog.

A limited attenuation high-pass filter for the KiwiSDR


KA7OEI published a new build:

One of the issues common with using a broad-band, direct-sampling SDR (software-defined radio) like the KiwiSDR is that of overload by strong, low-frequency signals, such as those on the AM (mediumwave) broadcast band – but there’s another problem that should be considered as well:  The high generally-high signal levels at lower HF frequencies.  If one looks at an spectrum analyzer connected to a broad-band receive  antenna during the evening, one will immediately note that the lower the frequency, the higher the signals seem – particularly the background noise.

See the full post on KA7OEI’s blog.

Building a DIY SMT pick & place machine with OpenPnP


Erich Styger has a nice write-up about building a DIY pick & place machine based on OpenPnP:

This article is about a project I have started back in January 2018. As for many of my projects, it took longer than anticipated.But now it is working, and the result is looking very good: a DIY automated pick and place machine to place parts on circuit boards. In the age of cheap PCBs, that machine closes the gap for small series of boards which have to be populated in a time consuming way otherwise.

See the full post on MCU on Eclipse blog.

Check out the video after the break.


DIY Arduino FM radio


Nick over at educ8s.tv shared detailed instructions of how to build this DIY Art Deco style FM Radio project using Arduino:

Let’s see what we are going to build today! As you can see, we are going to build an Art Deco style FM radio receiver. The design of this radio is based on this spectacular 1935 AWA radio. I discovered this old radio while searching online and also in this book about the most beautiful radios ever made. I loved the design of this radio so much that I wanted to have a similar one. So I devoted a month of my time to build my own.

Full details at educ8s.tv.

Check out the video after the break.

3D printed stirling engine gas burner and flywheel

Stirling Engine

The 3D printed Stirling Engine with its new gas burner and heavier flywheel from Do It Yourself Gadgets:

Take a look at my upgraded Stirling Engine with its new gas burner and flywheel!
If you take a look at my previous post you’ll see how I built a 3D printed holder for my Stirling Engine kit. Since I needed a constant heat source I added a small gas burner salvaged from an old BBQ lighter and attached it to the engine.

See the full post on Do It Yourself Gadgets blog.

Check out the video after the break.

TRL measurements with homemade VNA and open source software


Henrik Forstén writes:

I have been using the OSH Park’s 4 layer process a lot on my own projects. It has FR408 substrate that has better controlled permittivity and lower losses than ordinary FR-4 that other low cost PCB manufacturers use. In my opinion currently it is the best low cost process for making RF PCBs. My previous boards have worked pretty well, but I decided to make a test board that I can use to characterize the process better.
In the above picture is the test board that I made. It has two 50 ohm microstrip lines of different length, one open microstrip line, one microstrip line terminated with 50 ohm resistor and line with 0402 footprint that I populated with a 1 nF capacitor. I’m using this same type of capacitor as a general DC blocking capacitor in my VNA so I’m interested in finding out how it performs at high frequencies.

See the full post on Henrik’s blog.

Building a GBA LiPo voltage regulator and charger


Alex published a new build:

I saw a post where someone fitted a 2000mAh LiPo battery to their GBA, they had do to some modifications to the GBA battery compartment to fit it all. By using a LiPo battery instead of the AA’s, it would save us about 20 grams, while not a lot, ever gram does count and you can tell the difference plus since the LiPo has a higher voltage, it has a higher energy density, so it should give us longer play time than the AA’s. So I decided I would do the same mod and I might make a little voltage regulator and charging board to go along with it.

See the full post on insideGadgets project page.