The New Hotness

May 6, 2023 by Elliot Williams 35 Comments

If there’s one good thing to be said about the chip shortage of 2020-2023 (and counting!) it’s that a number of us were forced out of our ruts, and pushed to explore parts that we never would have otherwise. Or maybe it’s just me.

Back in the old times, I used to be a die-hard Atmel AVR fan for small projects, and an STM32 fan for anything larger. And I’ll freely admit, I got stuck in my ways. The incredible abundance of dev boards in the $2 range also helped keep me lazy. I had my thing, and I was fine sticking with it, admittedly due to the low price of those little blue pills.

And then came the drought, and like everyone else, my stockpile of microcontrollers started to dwindle. Replacements at $9 just weren’t an option, so I started looking around. And it’s with no small bit of shame that I’ll admit that I hadn’t been keeping up with the changes as much as I should have. Nowadays, it’s all ESP32s and RP2040s over here, and granted there’s a bit of a price bump, but the performance is there in abundance. But I can’t help feeling like I’m a few years back of the cutting edge.

So when I see work like what [CNLohr] and [Bitluni] are doing with the ultra-cheap CH32V003 microcontrollers, it makes me think that I need to start filling in gaps in my comfortable working-set of chips again. But how the heck am I supposed to keep up? And how do you? It took a global pandemic and silicon drought to force me out of my comfort zone last time. Can the simple allure of dirt-cheap chips get me out? We’ll see!

FET: Fun Endeavors Together

May 2, 2023 by Arya Voronova 42 Comments

Last time, we’ve looked over FET basics, details, nuances and caveats. Basics aren’t all there is to FETs, however – let’s go through real-world uses, in all their wonderful variety! I want to show you a bunch of cool circuits where a friendly FET, specifically a MOSFET, can help you – and, along the way, I’d also like to introduce you to a few FETs that I feel like you all could have a good long-term friendship with. If you don’t already know them, that is!

Driving Relays

Perhaps, that’s the single most popular use for an NPN transistor – driving coils, like relays or solenoids. We are quite used to driving relays with BJTs, typically an NPN – but it doesn’t have to be a BJT, FETs often will do the job just as fine! Here’s an N-FET, used in the exact same configuration as a typical BJT is, except instead of a base current limiting resistor, we have a gate-source resistor – you can’t quite solder the BJT out and solder the FET in after you have designed the board, but it’s a pretty seamless replacement otherwise. The freewheel (back EMF protection) diode is still needed for when you switch the relay and the coil produces wacky voltages in protest, but hey, can’t have every single aspect be superior.

The reason you can drive it the same way is quite simple: in the usual NPN circuit, the relay is driven by a 3.3 V or a 5 V logic level GPIO, and for small signal FETs, that is well within Vgs. However, if your MCU has 1.8 V GPIOs and your FET’s Vgs doesn’t quite cut it, an NPN transistor is a more advantageous solution, since that one will work as long as you can source the whatever little current and the measly 0.7 V needed.

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Hinges Live Inside 3D Prints

May 1, 2023 by Bryan Cockfield 5 Comments

Since desktop 3D printers have become more common, we’ve seen dramatic shifts in all kinds of areas such as rapid prototyping, antique restoration, mass production of consumer goods, or even household repairs that might not have been possible otherwise. There are a lot of unique manufacturing methods that can be explored in depth with a 3D printer as well, and [Slant 3D] demonstrates how one such method known as the living hinge can be created with this revolutionary new tool.

Living hinges, unlike a metal hinge you might pick up at a hardware store, are integrated into the design of the part and made of the same material. Typically found in plastic containers, they allow for flexibility while keeping parts count and cost low. The major downside is that they create stresses in the materials when used, so their lifespan is finite. But there are a number of ways to extend their life, albeit with a few trade-offs.

The first note is to make sure that you’re using the right kind of plastic, but after that’s taken care of [Slant 3D] builds a few flexible parts starting with longer circular-shaped living hinge which allows greater range of motion and distributes the forces across a wider area, at a cost of greater used space and increased complexity. A few other types of living hinges are shown to use less space in some areas, but make the hinges only suitable for use in other narrower applications.

One of the more interesting living hinges he demonstrates is one that’s more commonly seen in woodworking, known there as a kerf bend. By removing strips of material from a sheet, the entire sheet can be rotated around the cuts. In woodworking this is often done by subtracting material with a CNC machine or a laser cutter, but in 3D printing the voids can simply be designed into the part.

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Compressed Air Keeps Screws Moving Through Modular Production System

April 27, 2023 by Dan Maloney 8 Comments

If there’s an unsung hero of manufacturing, it’s the engineer who figures out how to handle huge numbers of small parts. It’s one thing to manually assemble something, picking each nut, bolt, and washer by hand. It’s another thing to build a machine that can do the same thing, but thousands of times in a row, ideally without making mistakes.

Most of us don’t need that level of automation in our processes, but when you do, it results in some interesting challenges. Take this pneumatic screw accelerator that [Christopher Helmke] designed for his modular production system. One of the custom machines in his system is a screw counter, which uses a magnetic wheel to feed screws — or nuts or washers — from a hopper, orient them correctly, and drop them into an output chute. While the counting bit worked quite well, parts would only go so far under the force of gravity in the clear vinyl tube used to connect the counter to the next process.

[Christopher]’s solution was simple but effective. His first prototype simply injects compressed air into the parts feed tube, which pushes the screws through the tubing. It works surprisingly well, propelling the parts through quite a long length of tubing, handling twisting paths easily and even working against gravity. Version 2 integrated the accelerator and a re-orienting fixture into a single part, which mates with a magazine that holds a large number of screws.

There are a lot of interesting features [Christoper] built into these simple parts that are worth keeping in mind. Our favorite is printing channels to guide small cable ties around the tubing to clamp it into the accelerator. We’ll be keeping that trick in mind.

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FET: The Friendly Efficient Transistor

April 25, 2023 by Arya Voronova 57 Comments

If you ever work with a circuit that controls a decent amount of current, you will often encounter a FET – a Field-Effect Transistor. Whether you want to control a couple of powerful LEDs, switch a USB device on and off, or drive a motor, somewhere in the picture, there’s usually a FET doing the heavy lifting. You might not be familiar with how a FET works, how to use one and what are the caveats – let’s go through the basics.

Here’s a simple FET circuit that lets you switch power to, say, a USB port, kind of like a valve that interrupts the current flow. This circuit uses a P-FET – to turn the power on, open the FET by bringing the GATE signal down to ground level, and to switch it off, close the FET by bringing the GATE back up, where the resistor holds it by default. If you want to control it from a 3.3 V MCU that can’t handle the high-side voltage on its pins, you can add a NPN transistor section as shown – this inverts the logic, making it into a more intuitive “high=on, low=off”, and, you no longer risk a GPIO!

This circuit is called a high-side switch – it enables you to toggle power to a device at will through a FET. It’s the most popular usecase for a FET, and if you’re wondering more about high-side switches, I highly recommend this brilliant article by our own [Bil Herd], where he shows you high-side switch basics in a simple and clear way. For this article, you can use this schematic as a reference of how FETs are typically used in a circuit.

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The BSides: More Curious Uses Of Off-the-shelf Parts

April 24, 2023 by Sonya Vasquez 10 Comments

Off-the-shelf stock parts are the blocks from which we build mechanical projects. And while plenty of parts have dedicated uses, I enjoy reusing them in ways that challenge what they were originally meant for while respecting the constraints of their construction. Building off of my piece from last time, I’d like to add to your mechanical hacking palette with four more ways we can re-use some familiar off-the-shelf parts. Continue reading “The BSides: More Curious Uses Of Off-the-shelf Parts” →

Ask Hackaday: Split Rail Op Amp Power Supply

April 20, 2023 by Al Williams 83 Comments

Water cooler talk at the office usually centers around movies, sports, or life events. Not at Hackaday. We have the oddest conversations and, this week, we are asking for your help. It is no secret that we have a special badge each year for Supercon. Have you ever wondered where those badges come from? Sometimes we do too. We can’t tell you what the badge is going to be for Supercon 2023, but here’s a chance for you to contribute to its design.

What I can tell you is that at least part of the badge is analog. Part, too, is digital. So we were discussing a seemingly simple question: How do we best generate a bipolar power source for the op amps on a badge? Like all design requests, this one is unreasonable. We want:

Ideally, we’d like a circuit to give us +/- 9 V to +/- 12 V at moderately low current, say in the tens of milliamps. Actual values TBD.
Low noise: analog circuitry, remember?
Lightweight: it is going on a badge
Battery operated: the badge thing again
Cheap: we only have a couple bucks in the budget for power
Available in quantity: we’ll need ~600 of these

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