Travelling The Oregon Trail With An Apple II Robot

February 18, 2019 by Brian Benchoff 5 Comments

For one reason or another, we’re going with a retro-futuristic 80s aesthetic in this case, [Mike] decided to turn an Apple IIe into a robot. If you have to ask why, you’ll never know, but this project does have some interesting things going for it. There’s a voice synthesizer, a brand spankin’ new power supply, and it rolls around on the floor thanks to Apple BASIC.

Since this is a mobile robot, there needs to be a power supply in there somewhere. The Apple II had a fantastic switching power supply, but it ran off mains voltage. To make this Apple run off a 14.8 V LiPO battery, [Mike] needed to re-engineer this power supply to give +5, +12, -5, and -12 Volts. The easiest is the positive voltage, and for that, he used a big ‘ol LM1084 linear regulator for the +5 V line. This outputs a ton of heat and probably isn’t the best solution, but it is a solution that works. The +12 line was again another linear regulator, an LM7812CV. Since this is dropping 14.8 V down to 12, the efficiency isn’t that bad, and since there’s no floppy drive it’s not pulling much current anyway. The negative voltages are a MAX764 / MAX765 inverting switching regulators. This completely replaces the original power supply in the Apple II, and is a decent reference design for anyone who wants to make a luggable Apple II laptop.

To move this thing around, the motors run on their own 11.1 V LiPO, with a bunch of Pololu gear tying everything together. The BASIC code was written on an emulator, transferred over with the Floppy Emu. Movement is controlled through the output pins on the joystick port, and there’s a text to speech module that was obviously needed and ties this project together wonderfully. You can check out the video demo of the build below.

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Electron Microscopes Are Awesome: Everything You Didn’t Know You Wanted To Know

February 18, 2019 by Mike Szczys 15 Comments

Electron microscopes were once the turf of research laboratories that could foot the hefty bill of procuring and maintaining such equipment. But old models have been finding their way into the hands of eager individuals who are giving us an inside look at the rare equipment. Before you start scouring Craigslist, go on a crash course of what you need to know with Adam McComb’s Hacker’s Guide to Electron Microscopy. He presented the talk at the 2018 Hackaday Superconference and the recording was just published, you’ll find it below.

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A Lightweight AVR IDE

February 17, 2019 by Lewin Day 11 Comments

It’s entirely possible to do your coding in vim or emacs, hammering out hotkeys to drive the interface and bring your code to life. While working in such a way has its charms, it can be confronting to new coders, and that’s before even considering trying to understand command line compiler settings. The greenhorn coder may find themselves more at home in the warm embrace of an IDE, and [morrows_end] has now built one for those working with AVR assembly code.

The IDE goes by the name of Simple AVR IDE, or savr_ide for short. Programmed in C++ with the FLTK widget library, [morrows_end] has tested it on Windows XP, but notes that it should successfully compile for Linux, Unix, and even MacOS too.

All the basic features are there – there’s syntax highlighting, as well as integration with the AVRA assembler and AVRDUDE for programming chips. It’s a tool that could make taking the leap into assembly code just that little bit easier. For another taste of bare metal coding, check out [Ben Jojo]’s discussion of x86 bootloaders.

A Network Card For The Trash-80

February 11, 2019 by Brian Benchoff 16 Comments

Around these parts, [Peter] is well-known for abusing the TRS-80 to do things it should never do. You can read Wikipedia on the TRS-80, you can look at Google Images, and you can browse the web. As with any retrocomputer, there are limitations for what you can do. To browse Wikipedia, [Peter] had to set up an AWS instance which translated everything and used serial to IP converters. It can be done, but it’s hard.

Now, after seeing a few interesting projects built around the ESP32, [Peter] built a network card for the TRS-80. It’s called the trsnic, and it’s a working network card for almost all the TRS-80s out there, with the eventual goal of supporting the TRS-80 Model I / II / III / 4 / 12 / 16 / 16B and 6000.

The idea for the trsnic comes from [Arno Puder]’s RetroStoreCard, a device that plugs into the TRS-80 Model III and connects it to a ‘personal cloud’ of sorts that hosts and runs applications without the need for cassettes or floppys. It does this with an ESP32 wired up to the I/O bus in the Model III, and it’s all completely Open Source.

[Peter] took this idea and ran with it. Thanks to the power found in the ESP32, real encrypted Internet communication can happen, and that means HTTPS and TLS.

Right now, documentation for the trsnic is limited, but the project does exist and building it is as easy as stuffing some headers and DIP sockets in a PCB and soldering them on. There’s a bit of work to do on the ESP32 code, but if you’re looking for a network card for your Trash-80, this is the one that works now.

Power Supply Design For Clean Jazz Amps

February 9, 2019 by Lewin Day 6 Comments

Power supply design is a broad field, requiring entirely different tools and techniques depending on what you’re working with. Creating a low-cost and compact mobile phone charger is a completely different ball game to designing the power supply for a medium-sized laser cutter, for example. [Vasily Ivanenko] has been designing a power supply for a clean jazz guitar amplifier, and has helpfully documented the process.

For a guitar amplifier which prides itself on clean tones, it’s highly important to avoid all sources of noise, to let the natural sound of the guitar come through as clearly as possible. [Vasily] notes that this requires careful component selection, as well as consideration of the placement of key parts and the construction of the power supply. Strategies to minimise inductive and capacitive coupling are discussed, as well as grounding schemes to minimise undesirable hum or buzz during amplifier operation.

The article is the first of a three part series, in which [Vasily] will then cover the full design of the guitar amp, including a focus on the design of the power amplifier stage. We’ve seen some of [Vasily]’s work before, like this discussion of how to build high quality audio amplifiers for ham radio use.

Simple Hand Tools Turn Brass And Steel Into An Amazing Astrolabe

February 9, 2019 by Dan Maloney 12 Comments

There’s something enchanting about ancient tools and instruments. The idea that our forebears were able to fashion precision mechanisms with nothing but the simplest hand tools is fascinating. And watching someone recreate the feat, such as by building an astrolabe by hand, can be very appealing too.

The astrolabe is an ancient astronomical tool of incredible versatility, allowing the user to do everything from calculating when the sun will rise to predicting the positions of dozens of stars in the night sky. That it accomplishes all this with only a few moving parts makes it all the more fascinating. [Uri Tuchman] began the astrolabe build shown in the video below with only a few hand tools. He quickly had his fill of the manual fretsaw work, though, and whipped up a simple scroll saw powered by an old sewing machine foot treadle to speed up his work. The real treat though is the hand engraving, a skill that [Uri] has clearly mastered. We couldn’t help musing that a CNC router could do the same thing so much more quickly, but watching [Uri] do it was so much more satisfying. Everything about the build really makes a statement, from the contrasting brass and steel parts to the choice of complex Arabic script for the markings. [Uri] has another video that goes over astrolabe basics and his design process that’s well worth watching too.

While it’s nowhere near as complicated an instrument, this astrolabe puts us in the mood to watch the entire Clickspring clock build again. And [Chris] is working on his own ancient instrument build at the moment, recreating the Antikythera mechanism. We can’t wait to binge-watch that one too.

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A Crash Course In 3D Printed Venturi Pumps

February 8, 2019 by Tom Nardi 15 Comments

Venturi pumps, commonly referred to as aspirators, are a fantastic way of moving around things which you might not want spinning around inside of a pump, and one of the easiest ways to create a vacuum. According to his research, [Tuval Ben Dosa] believed such a device would be a good way to move corrosive gasses which would normally eat up a blower fan; all he had to do was figure out how to 3D print one to his specifications.

Put simply: if you take a “T” shaped pipe and pass a fluid (such as air or water) through the straight section, a vacuum will be created on the shorter side due to the Venturi effect. As long as you don’t mind the substance you wish to pump getting mixed into your working fluid, it’s a simple way to bring something “along for the ride” as the fluid makes its way through the pipe.

[Tuval] needed a way to remove the chlorine gasses produced by his PCB etching station, and an aspirator seemed like the perfect solution. He just needed to pump clean air through a Venturi, which would suck up the chlorine gas on the way through, and ultimately carry it outside. But he soon found that while a pump based on the Venturi effect is simple conceptually, getting it to work in the real world is a bit trickier. Especially when you’re dealing with something like 3D printing, which brings in its own unique challenges.

He tried modeling a few designs he found online in 3D and printing them out, but none of them worked as expected. The most common problem was simply that no vacuum was being generated, air was freely moving out of both sides. While [Tuval] doesn’t claim to have any great knowledge of fluid dynamics, he reasoned that the issue was due to the fact that most Venturi pumps seem designed to move water rather than air. So he designed a new version of the pump which had a more pronounced nozzle on the inlet surrounded by a cavity in which the gases could mix.

His modified design worked, and now anyone with a 3D printer can run off their own Venturi device for quickly and easily giving potentially harmful fumes or gases the boot. If this is one of those things you’d feel more comfortable buying than building, don’t worry, we’ve previously covered using a low-cost aspirator as a vacuum source in the home lab.