Drifting Instrument Presents Opportunity to Learn about Crystal Oscillators

Sure, we all love fixing stuff, but there’s often a fine line between something that’s worth repairing and something that’s cheaper in the long run to just replace. That line gets blurred, though, when there’s something to be learned from a repair.

This wonky temperature-compensated crystal oscillator is a good example of leaning toward repair just for the opportunity to peek inside. [Kerry Wong] identified it as the problem behind a programmable frequency counter reading significantly low. A TCXO is supposed to output a fixed frequency signal that stays stable over a range of temperatures by using a temperature sensor to adjust a voltage-controlled oscillator that corrects for the crystal’s natural tendency to vary its frequency as it gets hotter or colder. But this TCXO was pretty old, and even the trimmer capacitor provided was no longer enough to nudge it back in range. [Kerry] did some Dremel surgery on the case and came to the conclusion that adding another trim cap between one of the crystal’s leads and ground would help. This gave him a much wider adjustment range and let him zero in on the correct 10-MHz setting. [Mr. Murphy] still runs the show, though – after he got the TCXO buttoned up with the new trimmer inaccessible, he found that the frequency was not quite right. But going from 2 kHz off to only 2 Hz is still pretty good.

Whether it’s the weird world of microwave electronics or building a whole-house battery bank, it’s always fun to watch [Kerry]’s videos, and we usually end up learning a thing or two.

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Resistance in Motion: What You Should Know About Variable Resistors

Adjusting the volume dial on a sound system, sensing your finger position on a touch screen, and knowing when someone’s in the car are just a few examples of where you encounter variable resistors in everyday life. The ability to change resistance means the ability to interact, and that’s why variable resistance devices are found in so many things.

The principles are the same, but there are so many ways to split a volt. Let’s take a look at what goes into rotary pots, rheostats, membrane potentiometers, resistive touchscreens, force sensitive resistors, as well as flex and stretch sensors.

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Second Skin Synth Fits Like a Glove

California textiles artist and musician [push_reset] challenged herself to make a wearable, gesture-based synth without using flex-sensing resistors. In the end, she designed almost every bit of it from the ground up using conductive fabric, resistive paint, and 3-D printed parts.

A couple of fingers do double duty in this glove. Each of the four fingertips have a sensor made from polyurethane, conductive paint, and conductive fabric that is connected to wires using small rivets. These sensors trigger different samples on an Edison that are generated with Timbre.js. The index and middle fingers also have knuckle actuators made from 3-D printed pin-and-slot mechanisms that turn trimmer pots. Bending one knuckle changes the delay timing while the other manipulates a triangle wave.

On the back of the glove are two sensors made from conductive fabric. Touching one up and down the length will alter the reverb. Sliding up and down the other alters the frequency of a sine wave. [push_reset] has kindly provided everything necessary to re-create this build from the glove pattern to the STL files for the knuckle actuators. Check out a short demonstration of the glove after the break. If you love a parade, here’s a wearable synth that emulates a marching band.

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Modified Mower Hacks the Heavy Stuff

Clearing brush is no fun. Sure, swinging a machete on a hot, humid day sounds great, but when you’re sitting in an oatmeal bath the next day because you didn’t see the poison ivy, you’ll be looking for a better way. [RoboMonkey] did just that with a field-expedient brush trimmer that’s sure to help with his chores.

This is a hack in the true Junkyard Wars sense of the word. A cast-off electric push mower deck caught [RoboMonkey]’s eye, and a few spare brackets and bolts later his electric hedge trimmer was attached across the front of the mower. With a long extension cord trailing behind, he was able to complete in 10 minutes what would normally take him an hour to accomplish, without spending a dime on either a specialized brush cutter or a landscaping service. The video after the break reveals that it may not be the most powerful tool in the shed, and it won’t likely stand up to daily use, but for this twice a year chore, it’s more than sufficient. And since the hedge trimmer wasn’t modified, it’s still available for its original purpose. Reduce, reuse, recycle – and repurpose.

While we haven’t seen many brush cutters before, we seen plenty of mower mods. From LiPo electrics to a gas-powered RC unit, the common push-mower seems to be a great platform for all kinds of hacking.

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[Lou’s] haircut really sucks

Ah yes, at some point a brilliant inventor combined the electric trimmer with a vacuum cleaner and the art of cutting hair was never the same again. [Lou] is showing us how to give a haircut that really sucks up the waste. And he did it using rubbish he had lying around.

Most people will recognize this as a DIY version of the Flowbee. Not surprisingly, you can still buy one of those if you want, but [Lou] is looking for a vacuum cutter for trimming his dog’s hair so he’s not about to shell out cash for it. He already has the trimmer, and just needed a way to attach the vacuum hose to it. In the image above you can see the grey crevice attachment for his vacuum. He taped it onto the trimmers, then cut a plastic soda bottle to use as a hood near the business end of the trimmer. It’s all wrapped in packing tape to hold everything in place and seal around the joints. You can see it in action in the clip after the break.

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How to convert an internal combustion engine to run from steam power

We had no idea that what’s needed to convert an internal combustion engine to steam power is actually rather trivial. [David Nash] shows us how it’s done by performing the alterations on the engine of a string trimmer. These are the tools used to cut down vegetation around obstacles in your yard. The source of the engine doesn’t really matter as long as it’s a 2-cycle motor.

This engine had one spark plug which is threaded into the top of the block. [David] removed this and attached his replacement hardware. For now he’s using compressed air for development, but will connected the final version to a boiler.

There are only a couple of important parts between the engine and the boiler. There’s an in-line oil reservoir to help combat the corrosive nature of the steam. There is also a check valve. In the video after the break [David] shows the hunk of a ball-point pen that he uses to actuate the check valve. It’s really just a spacer that the piston pushes up to open the valve. This will be replaced with a metal rod in the final version.

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