Roll Your Own Servo

October 4, 2023 by Al Williams 51 Comments

Usually, when you want a servo motor, you simply buy one already made. But if you need something unusual, you can turn any DC motor into a custom servo you can control just like [Dejan] did. You can watch a video of the process below.

The custom servo can tune the endpoints, the center point, and the sensitivity. It also can be set to handle continuous rotation. A 12-bit encoder tells the microcontroller where the motor is and the output drivers can handle over 3 A of motor current. The microprocessor is a tried-and-true ATmega328. [Dejan] wanted to make the board as small as possible, and we think 40 mm square isn’t bad at all. There is also a 3D printed gearbox and housing. Overall, a very well-done project.

The motor control uses a PID algorithm. Potentiometers set the end range and sensitivity. A push button allows resetting the center position. DIP switches control the mode. The video shows a computer and an RC controller setting the position of the motors.

We have, of course, seen many variations on this idea. We’ve also seen servos rebuilt for better performance.

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ARPA-H Moonshot Project Aims To Enable 3D Printing Of Human Organs

October 4, 2023 by Maya Posch 9 Comments

The field of therapeutic cloning has long sought to provide a way to create replacement organs and tissues from a patient’s own cells, with the most recent boost coming from the US Advanced Research Projects Agency for Health (ARPA-H) and a large federal contract awarded to Stanford University.

Patients on the organ donation waiting list in the US (Source: HRSA)

The creatively named Health Enabling Advancements through Regenerative Tissue Printing (HEART) project entails a 26.3 million USD grant that will be used to create a functioning bioprinter backed by a bank of bioreactors. Each bioreactor will cultivate a specific type of cell, which will then be ‘printed’ in its proper place to gradually build up the target organ or tissue. The project’s five year goal is the printing of a fully functioning human heart and implanting it into a pig.

Assuming this is successful, the general procedure can then be refined to allow for testing with human patients, as well as the bioprinting of not just hearts, but also lungs, kidneys and much more. The lead investigator at Stanford University, [Mark Skylar-Scott], cautions that use with human patients is likely to be still decades off. But the lifesaving potential of this technology, once matured, is staggering. This is highlighted by data from the US HRSA, with over 42,000 transplants in 2022 in the US alone, with over a hundred-thousand patients waiting and 17 people who die each day before an organ becomes available.

Peggyboard Will Have You Climbing The Walls Repeatedly

October 3, 2023 by Kristina Panos 2 Comments

When you can’t climb actual rocks all the time, what do you do to train and keep sharp? You go to a rock-climbing gym, naturally. But what do you do when it’s 2020 and your rock-climbing gym has shuttered for the foreseeable? You build the best darn rock-climbing wall possible, and you outfit it with an LED for every hold and write an app that lets you plan your route and repeat it later.

This is essentially a DIY version of something called a Moonboard, which, aside from being expensive, was quickly going out of stock back in 2020. [Pegor] started the Peggyboard by building a climbing woody, which is a legendary home climbing wall built by a legendary climber about 20 years ago.

The Peggyboard is Raspberry Pi-powered and has a rather nice app going for it, which [Pegor] has kindly decided to open source.

On the initial screen, the user can select a route and assign the holds as either starting holds, foot holds, hand holds, or finishing holds, each with a different color LED. Another screen lets the user choose a previously-saved route, then apply it to the Peggyboard’s LEDs with the light bulb icon.

Don’t know where to get started building your own climbing wall? You can 3D print climbing holds, you know.

Bioadhesive Polymer Semiconductors For In-Vivo Sensors

October 3, 2023 by Maya Posch 2 Comments

What do you do when you want to stick an electrode or even an couple of sensors to an internal organ, such as a heart? Generally you’d use some kind of special adhesive, or sutures to ensure that the item remains firmly in place and doesn’t migrate to somewhere else within the chest cavity or among the intestines. According to a new study (press release) by Nan Li and colleagues in Science there may however be a more elegant method, using bioadhesive polymers.

The double-network copolymer is designed so that once put in the desired location it soaks up moisture and provides a dry interface for its bioadhesive properties. In addition, the resulting material is electrically conductive, with a measured charge-carrier mobility of ~1 square centimeter per volt per second.

Using thus manufactured electrodes were applied to both an isolated rat heart and in vivo rat muscles to measure electrical currents produced by each respective tissue type. The authors of the study envision that using this technology more complicated interfaces and sensors can be developed that would interface directly with organs and related. The claimed biocompatibility would also allow for such devices to be left in-situ for extended periods of time, which could be a boon for a wide range of medical conditions where continuous monitoring is a crucial element.

Life-Sized Rock’em Sock’em Robot Will Definitely Knock Your Block Off

October 3, 2023 by Richard Baguley 2 Comments

He knocked his block off! That’s what [Zach] of Byte Sized Engineering is planning on saying when he completes this Rock’em Sock’em Robots replica. The twist? His replica is going to be life-sized. The original game involved two players, each controlling a robot that could punch and block with two lever-driven arms. [Zach] is looking to scale that up to human sized, but with a few interesting technical additions.

This build might be a bit large to be driven by a small child, so for the punching action [Zach] is using a four-bar linkage moved by a pneumatic cylinder. After some modelling, he decided on a 16mm bore and 100mm stroke cylinder that should provide a good, quick pneumatic action, but without putting so much force in that it destroys the whole thing. The aim is to knock his block off, not to permanently remove his block and take someone else’s block with it. This first video details his first prototype of the arm and the first set of tests, with later videos hopefully getting more into the mechanism and technical details of the build. We’d also like to see (hint, hint [Zach]) some of the files and code to follow up with.

Bonus fact: as older Brits may tell you, the game was marketed for some time there under the name “Raving Bonkers“, with the robots renamed as Basher Bonker and Biffer Bonker. The name didn’t catch on, and they changed back to the Rock’em Sock’em robots name. Ask someone in the UK these days if they want to play raving bonkers with your basher, and you will probably get your own block knocked off. Video below the break. Continue reading “Life-Sized Rock’em Sock’em Robot Will Definitely Knock Your Block Off” →

2023 Halloween Hackfest: Treat Trough Of Terror Is Actually Pretty Cute

October 3, 2023 by Kristina Panos 7 Comments

Even though it seems the worst of COVID has passed, October generally kicks off cold and flu season, so why not continue to pass out Halloween treats in a socially-distanced fashion?

That is, of course the idea behind [Gord Payne]’s Halloween Treat Trough of Terror. Lay a treat at the top of the trough and it will activate the LED strips that follow the treat down to the end, as well as some spooky sounds. The treat in question is detected by an SR-04 ultrasonic distance sensor connected to an Arduino Nano.

All in all this was a highly successful build as far as neighborhood entertainment value goes. Toddlers stared in awe at the blinkenlights, teenagers proclaimed it ‘sick’, and we can only assume that the adults were likely happy to see something aimed at kids that’s not scary.

[Gord] has a nice how-to if you want to build your own, and of course, the Arduino sketch is available. Be sure to check it out in action after the break.

Don’t have room to build a treat slide? Here’s a socially-distanced dispenser that lets them stomp a giant button.

Continue reading “2023 Halloween Hackfest: Treat Trough Of Terror Is Actually Pretty Cute” →

Bus Sniffing The Model 5150 For Better Emulation

October 3, 2023 by Dan Maloney 6 Comments

At the risk of stating the obvious, a PC is more than just its processor. And if you want to accurately emulate what’s going on inside the CPU, you’d do well to pay attention to the rest of the machine, as [GloriousCow] shows us by bus-sniffing the original IBM Model 5150.

A little background is perhaps in order. Earlier this year, [GloriousCow] revealed MartyPC, the cycle-accurate 8088 emulator written entirely in Rust. A cycle-accurate emulation of the original IBM PC is perhaps a bit overkill, unless of course you need to run something like Area 5150, a demo that stretches what’s possible with the original PC architecture but is notoriously finicky about what hardware it runs on.

Getting Area 5150 running on an emulator wasn’t enough for [GloriousCow], though, so a deep dive into exactly what’s happening on the bus of an original IBM Model 5150 was in order. After toying with and wisely dismissing several homebrew logic analyzer solutions, a DSLogic U3Pro32 logic analyzer was drafted into the project.

Fitting the probes for the 32-channel instrument could have been a problem except for the rarely populated socket for the 8087 floating-point coprocessor on the motherboard. A custom adapter gave access to most of the interesting lines, including address and data buses, while a few more signals, like the CGA sync lines, were tapped directly off the video card.

Capturing one second of operation yielded a whopping 1.48 GB CSV file, but a little massaging with Python trimmed the file considerably. That’s when the real fun began, strangely enough in Excel, which [GloriousCow] used as an ad hoc but quite effective visualization tool, thanks to the clever use of custom formatting. We especially like the column that shows low-to-high transitions as a square wave — going down the column, sure, but still really useful.

The whole thing is a powerful toolkit for exploring the action on the bus during the execution of Area 5150, only part of which [GloriousCow] has undertaken as yet. We’ll be eagerly awaiting the next steps on this one — maybe it’ll even help get the demo running as well as 8088MPH on a modded Book8088.