Stepper Motors Quick And Simple

April 9, 2021 by Chris Lott 37 Comments

If you want a simple and easy introduction to stepper motors, check out the [IMSAI Guy]’s short video where he designs a very basic stepper motor controller and packs in a lot of quick lessons along the way. (Embedded below.)

He first goes over the fundamentals of a stepper motor in a practical, hands-on approach, and also shows us how to ring out the connections if the pinout is unknown. Next he demonstrates stepping the motor manually and then makes a simple FET driver circuit. Just when you’re expecting a small microcontroller to appear, the [IMSAI Guy] instead digs deep into his junk box and explains how to drive the motor with a 22V10 GAL (an electrically erasable PAL) and a 555 timer module. Based on a clearly-explained logic table for driving the coils, a sneaky way to introduce Karnaugh maps, he proceeds to write the output equations in WinCUPL.

Mature Readers will recall the “Happy PAL” Character

WinCUPL is the modern version of CUPL (Compiler for Universal Programmable Logic) originally written by a company called Assisted Technology, now owned by Altium. CUPL and peers like PALASM from Monolithic Memories, Inc. (MMI) and ABEL from Data I/O Corporation were basic Hardware Description Languages specifically designed for PALs, GALs, and CPLDs. PALs were small arrays of logic gates with fusible interconnections, and your design is “burned” into the fuses much like a (EE)PROM. When designing with PALs, you could clearly visualize the connections in your mind, something that has since been remedied by the advent of modern FPGAs.

Alas, he cuts out the part where the source code is compiled and the 22V10 is programmed, and jumps directly into testing the circuit on a breadboard. Spoiler alert — it does work. Zooming in close and squinting, the nifty 555 timer breadboard module that he points out is called a TP353, which you can find from your favorite online supplier.

There is a lot to learn in this tutorial, and the [IMSAI Guy] does a great job at making the subject approachable to hobbyists and novices. We also covered another of his tutorials a couple of weeks ago on image sensors. Thanks to [itsevilbert] for the tip.

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Code Your Own Twitch Chat Controls For Robots — Or Just About Anything Else!

April 8, 2021 by Lewin Day 4 Comments

Twitch Plays Pokemon burst onto the then nascent livestreaming scene back in 2014, letting Twitch viewers take command of a Game Boy emulator running Pokemon Red via simple chat commands. Since then, the same concept has been applied to everything under the sun. Other video games, installing Linux, and even trading on the New York Stock Exchange have all been gameified through Twitch chat.

*TwitchPlaysPokemon* started a craze in crowdsourced control of video games, robots, and just about everything else.

You, thirsty reader, are wondering how you can get a slice of this delicious action. Fear not, for with a bit of ramshackle code, you can let Twitch chat take over pretty much anything in, on, or around your computer.

It’s Just IRC

The great thing about Twitch chat is that it runs on vanilla IRC (Internet Relay Chat). The protocol has been around forever, and libraries exist to make interfacing easy. Just like the original streamer behind Twitch Plays Pokemon, we’re going to use Python because it’s great for fun little experiments like these. With that said, any language will do fine — just apply the same techniques in the relevant syntax.

SimpleTwitchCommander, as I’ve named it on Github, assumes some familiarity with basic Python programming. The code will allow you to take commands from chat in two ways. Commands from chat can be tabulated, and only the one with the most votes executed, or every single command can be acted on directly. Actually getting this code to control your robot, video game, or pet viper is up to you. What we’re doing here is interfacing with Twitch chat and pulling out commands so you can make it do whatever you like. With that said, for this example, we’ve set up the code to parse commands for a simple wheeled robot. Let’s dive in.

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Solid Tips For Casting Colored Silicone Tires

April 5, 2021 by Donald Papp 13 Comments

For people who work with wheeled robots or RC vehicles, sooner or later one gets interested in making custom tires instead of dealing with whatever is available off the shelf. [concreted0g]’s preferred method is to design and 3D print wheel hubs, then cast some custom silicone tires to fit over them. Of course, the devil is in the details and this process can be a bit messy, so he’s shared useful tips on how to get reliable results with simple materials.

The casting material is cheap silicone caulking from a hardware store, and color can be added with a small amount of cheap acrylic paint. A few drops of glycerin added to the silicone thins it out slightly and helps it flow into a mold better. Mix well (the paint will also serve as a visual indicator of how well it is mixed), then scoop the mixture into the mold while trying to avoid creating air pockets. If your mold is in two pieces, assemble the mold and remove any overflow, then let it sit undisturbed for at least several hours while it cures.

Mounting the resulting tire to a wheel hub can be done with a thin film of super glue, which seems to work perfectly well for small tires and is easy to apply.

The rules are going to be a bit different for big objects. We know that silicone caulking can have difficulty fully curing when it’s applied thickly, especially when sealed into a mold with little to no airflow. In such cases, adding cornstarch (in about a 5:1 ratio of silicone to cornstarch by volume) is all that it takes to cure even thick wads of goop in less than an hour. Stirring cornstarch in tends to introduce more air bubbles into the mixture, but for larger pieces that can be an acceptable tradeoff. Cheap silicone caulking is versatile stuff, one just needs to know what to expect, and take a few steps to deal with the messiness.

Need something tougher? Maybe check out using slices of automotive silicone hose for robot wheels to get something that works just as well, but is a lot more durable.

Serial Silicone Molding

March 26, 2021 by Chris Lott 5 Comments

The techniques for making single-digit quantities of custom molded parts don’t scale well when you need to make dozens, as [Kevin Holmes] discovered. He needed to make 80-some sets of a silicone motor mount, and the one-up mold process was not going to work. He explores several solutions, which he rejects as being too complicated. Finally [Kevin] comes up with the idea of daisy-chaining banks of molds clamped together with rails of stock metal bars. It’s a pretty nifty process to watch and you can check the video out below, which is not unlike a very slow 7495 four-bit shift register.

Even though the silicone he uses is clear, pay attention and you can still see the carry-out as it propagates from mold to mold. He manually performs the nibble carry operation from one bank to the next — we wonder if he could cascade these banks, and inject all 80 in one really big squeeze?

Why would someone need 80 sets of silicone rubber motor mounts, you may ask? Well, you may remember the 4-mation 3D zoetrope that we wrote about back in 2018. [Kevin] is one of the founders of this mesmerizing project, and it would seem that their Kickstarter project has been successful. As he demonstrates in the video below, without some type of noise dampening mounts, a rumble from the motor is amplified through the stage of the zoetrope. If you have any favorite mold-making tips for small batch manufacturing, let us know in the comments below. Thanks to [George Graves] for sending this tip our way.

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Digital PlayStation 3 Purchases May Only Live As Long As Your PRAM Battery Without Sony Servers

March 23, 2021 by Drew Littrell 105 Comments

Word of Sony shutting down PlayStation storefront servers for PS3 this summer spread like wildfire on the internet Monday. The discourse in comment sections were filled with anti-DRM rhetoric and renewed pledges of physical-only game collections, because without content servers to connect to, your digital PS3 purchases will eventually become unplayable. Even if legitimate purchases are installed to the console’s hard drive before Sony “flips the switch”, they may only live on as long as the internal clock stays in sync. Which is why this guide to replace a PS3 PRAM battery written by [Andrew] has renewed importance. After a battery replacement the internal clock needs to be reset and this requires validation from the PlayStation network (you know, the one that’s soon to be shut down).

Game preservationist group [Does it play?] drove home the impact of such a business decision by Sony on Twitter. The thread is quick to point out that even if users are quick to re-download all of their purchases to a PS3 system before the purported July 2nd deadline, those games will eventually become unplayable if the system clock becomes desynchronized. Replacing the PRAM battery and reconnecting to the PlayStation Network prior to Sony shuttering their servers should buy the user some more playtime. However, without any further changes to Sony’s licensing policy little else can be done physically to ensure those digital PS3 games will work in perpetuity.

Sony isn’t the only one to have drawn the ire of digital rights advocates in regards to terminating their online services. Nintendo shuttered the DSI-Shop in 2017 and Microsoft turned off access to the original Xbox LIVE servers in 2010. The big three console makers have all let their consumers down by removing the ability to reacquire purchases in some way, but the fact that so many PS3 exclusives were only ever available digitally just further exacerbates issues with digital rights. Dropping in a fresh coin-cell may not be the permanent solution everyone is looking for at the moment, but it couldn’t hurt to re-familiarize yourself with the Cell processor.

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Build-It-Yourself LC Meter

March 22, 2021 by Stephen Ogier 31 Comments

A basic digital multimeter (DMM) is usually the first measurement tool the aspiring electronics tinkerer buys. Even a bargain-bin DMM will happily measure voltage, current, and resistance; check continuity; and may even have a mode to measure transistor gain. Every toolbox needs at least one DMM, but most have an crucial limitation— they can’t measure two of the fundamental electrical quantities: inductance and capacitance. On Hackaday.io, [core weaver] has developed an open-source LC meter to allow you to build your own tool to measure inductance and capacitance.

[core weaver]’s design is all through-hole, so even just assembling one would be a great exercise for someone getting started in electronics. However, he didn’t just release a design, in a series of videos he goes through the theory of the device’s operation; explains the design of the circuit, firmware, and case; and shows you how to put it all together. For times when you need to measure a lot of parts (e.g. if you have to sort a bag of cheap capacitors looking for specific value), he’s even developed a desktop program to save you some trouble!

The finished meter looks incredible! If you want to build one for yourself, he’s put all of the files up on GitHub, and we highly recommend you check out his first video after the break. If you’d like to build yourself a 6.5-digit DMM to go with our LC Meter, consider this one which even has a home-built ADC.

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Lost A Lightweight Quadcopter? Here Are The Best Ways To Find It

March 6, 2021 by Donald Papp 24 Comments

Lost aircraft are harder to find when they are physically small to begin with. Not only are they harder to see, but the smaller units lack features like GPS tracking; it’s not normally possible to add it to a tiny aircraft that can’t handle much more than its own weight in the first place. As a result, little lost quads tend to be trickier to recover in general.

Fluorescent tape adds negligible weight, and will glow brightly at night under a UV light.

The good news is that [Eric Brasseur] has shared some concise tips on how to more easily locate and recover lost aircraft, especially lightweight ones. Recovering aircraft is something every aircraft hobbyist has had to deal with in one way or another, but [Eric] really has gathered an impressive list of tricks and techniques, and some of them go into some really useful additional detail. It occurs to us that a lot of these tips could apply equally well to outdoor robots, or rovers.

Even simple techniques can be refined. For example, using bright colors on an aircraft is an obvious way to increase visibility, but some colors are better choices than others. Bright orange, white, and red are good choices because they are easily detected by the human eye while still being uncommon in nature. Violet, blue, and even cyan on the other hand may seem to be good choices when viewed indoors on a workbench, but if the quad is stuck in dark bushes, those colors will no longer stand out. Another good tip is to consider also adding a few patches of fluorescent tape to the aircraft. If all else fails, return at night with a UV lamp; those patches will glow brightly, and be easily seen from tens of meters.

Some of the tips are used while the device still has power, while others don’t depend on batteries holding out. [Eric] does a great job of summing up those and many more, so take a look. They might come in handy when test flying quadcopters that are little more than an 18650 cell, motors, and a 3D-printable frame.