Tool Hacks

3005 Articles

Current Source Mixes Old School And New

August 12, 2025 by 2 Comments

At first glance, [RobBest]’s constant current source looks old school. The box is somewhat old-fashioned, featuring switches and binding posts. Most importantly, there’s a large analog meter dominating the front panel. Then you notice the OLED display, and you know something’s up.

The device can source or sink a constant current. In addition, it features a timer that calculates milliamp-hours and automatically turns off when not in use. The brain is a PIC 16F1765, which controls the screen, the buttons, and a few relays. While that might seem an odd choice for the processor, it is actually smart. The device has both a DAC and an ADC, plus an internal op amp. The analog output and a single pass transistor control the current flow, while the two relays flip it between a source and a sink.

Without that op amp, the DAC can’t produce much current. However, by passing it through the onboard amplifier, the output can drive about 100 mA, which is sufficient for this project.

This is a classic circuit, but the addition of a CPU and a display gives it capabilities that would have been very difficult to build back in the day. Want to dive into the theory behind constant current sources?  Or just the practical use of a voltage regulator to make one?

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Calipers: Do You Get What You Pay For?

August 11, 2025 by 37 Comments

Generally, you think that if you pay more for something, it must be better, right? But that’s not always true. Even if it is true at the lower end, sometimes premium brands are just barely better than the midrange. [Project Farm] looks at a bunch of different calipers — a constant fixture around the shop if you do any machining, 3D printing, or PCB layout. The price range spans from less than $10 for some Harbor Freight specials to brands like Mitutoyo, which cost well over $100. Where’s the sweet spot? See the video below to find out.

The first part of the video covers how much the units weigh, how smooth the action is, and how much force it takes to push it down. However, those are not what you probably care most about. The real questions are how accurate and repeatable they are.

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A Portable 12 VDC Water Chiller For The Chemistry Lab

August 6, 2025 by 20 Comments

Having a chiller is often essential for the chemistry laboratory, but what if you’re somewhere without easy access to water, nevermind a mains outlet to plug your usual chiller into? In that case you can build a portable one that will happily run off the 12 VDC provided by a mobile source like the accessory outlet in a car while reusing the water from its reservoir, as demonstrated by [Markus Bindhammer] in a recent video.

The build uses a compressor-based freezer as the base, which is significantly more capable than the typical Peltier-cooled refrigerators that cannot cool as fast or efficiently. The changes he made involve running in- and outlet tubing into the freezer’s compartment, with a submerged 12 VDC water pump providing the water to the outlet. This pump is controlled by a variable speed controller board that’s put in a box on the outside with the power lead also sneaking into the freezer. With these modifications in place the freezer’s functionality isn’t significantly impacted, so it can be used as normal.

After filling the compartment with water, the lid is closed and the freezer engaged. The pump controller is then switched on, with the water flow adjusted to fit the distillation job at hand. Although in this case a fairly small freezer was modified, nobody is saying that you cannot also do it with a much larger freezer, and fill it with ice cream and other treats to help it and lab critters cool down faster.

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A Speed Loader For Your 3D Printer Filament

August 6, 2025 by 23 Comments

Reloading filament on a 3D printer is hardly anyone’s favorite task, but it’s even worse when you’re trying to shove stiff filament down a long and winding Bowden tube. Enter the speed loader from [Mr Flippant], which aims to take the pain out of this mechanically-frustrating chore.

The design is simple enough. It’s a small handheld tool that uses a 12 VDC gear motor to drive a set of Bondtech-style drive gears that you might find in an extruder. They’re assembled in a 3D printed housing with a microswitch to activate the motor, and a 9 volt battery to supply the juice.

To use the device, first thread the filament into the beginning of the Bowden tube. The idler gear is on a hinge, such that clamping it into position around the filament with the main gear activates the microswitch and turns the motor on, driving the filament all the way to the extruder. Job done! [Mr Flippant] notes that the filament should be as straight and unkinked as possible for best results, but that’s good advice when 3D printing in general.

Funnily enough, around these parts, when we talk about speed loaders, we’re usually discussing tapes.

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2025 One Hertz Challenge: 4-Function Frequency Counter

July 31, 2025 by 1 Comment

Frequency! It’s an important thing to measure, which is why [Jacques Pelletier] built a frequency counter some time ago. The four-function unit is humble, capable, and also an entry into our 2025 One Hertz Challenge!

The build began “a long while ago when electronic parts were still available in local stores,” notes Jacques, dating the project somewhat. The manner of construction, too, is thoroughly old-school. The project case and the sweet red digits are both classic, but so is what’s inside. The counter is based around 4553 BCD counter chips and 4511 decoder ICs. Laced together, the logic both counts frequency in binary-coded decimal and then converts that into the right set of signals to drive the 7-segment displays. Sample time is either 1 Hz or 0.1 Hz, which is derived from an 8MHz oscillator. It can act as a frequency meter, period meter, chronometer, or a basic counter. The whole build is all raw logic chips, there are no microprocessors or microcontrollers involved.

It just goes to show, you can build plenty of useful things without relying on code and RAM and all that nonsense. You just need some CMOS chips and a bucket of smarts to get the job done!

2025 Hackaday One Hertz Challenge
Stephen Hawes operating his LumenPnP

The LumenPnP Pasting Utility: Never Buy Solder Stencils Again?

July 30, 2025 by 11 Comments

Over on his YouTube channel the vivacious [Stephen Hawes] tells us that we never need to buy solder stencils again!

A big claim! And he is quick to admit that his printed solder paste isn’t presently quite as precise as solder stencils, but he is reporting good success with his technique so far.

[Stephen] found that he could print PCBs with his fiber laser, populate his boards with his LumenPnP, and reflow with his oven, but… what about paste? [Stephen] tried making stencils, and in his words: “it sucked!” So he asked himself: what if he didn’t need a stencil? He built a Gerber processing, G-code generating, machine-vision implemented… website. The LumenPnP Pasting Utility: https://paste.opulo.io/

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Signal Injector Might Still Be Handy

July 26, 2025 by 1 Comment

Repairing radios was easier when radios were simple. There were typically two strategies. You could use a signal tracer (an amplifier) to listen at the volume control. If you heard something, the problem was after the volume control. If you didn’t, then the problem was something earlier in the signal path. Then you find a point halfway again, and probe again. No signal tracer? You can also inject a signal. If you hear it, the problem is before the volume. If not, it is after. But where do you get the signal to inject? [Learn Electronics Repair] sets out to make a small one in a recent video you can see below.

Both signal tracers and injectors were once ubiquitous pieces of equipment when better options were expensive. However, these days, you can substitute an oscilloscope for a signal tracer and a signal generator for an injector. Still, it is a fun project, and a small dedicated instrument can be handy if you repair a lot of radios.

The origin of this project was from an earlier signal injector design and a bet with a friend about making a small version. They are both working on their designs and want people to submit their own designs for a little ad hoc contest.

We always preferred a signal tracer since it is more passive. Those were typically just audio amplifiers with an optional diode in the input to demodulate RF. A computer amplified speaker and a diode can do the job, as can an LM386. Or, you can build something complex, if you prefer.

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