Half Power Bank, Half Spot Welder

January 8, 2024 by Jenny List 13 Comments

There was a time when every gizmo on AliExpress also had a big white LED so it could also work as a flashlight, but maybe the power bank is the new flashlight. [Aaron Christophel] has a battery spot welder that costs a not unreasonable 30 euros and can also be used as a novelty power bank. He subjects it to a test and teardown in the video below the break.

First of all, he conducts a few weld tests, and we have to say it seems capable of some reasonable results if its parameters are correctly adjusted. Then the end comes off the extruded aluminium case, and the guts of the device are slid out for a teardown.

The power comes from a pair of Li-Po pouch cells, while on the board, there’s an STM32 clone providing the timing for a set of MOSFETs that do the heavy lifting. There’s a colour display for tweaking the settings. Alongside all this, there’s also a small chip for that power bank functionality. Charging is via USB-C, though, of course, it’s not really proper USB-C but a USB-C socket that expects 5 volts. This is a disappointing trend in cheap electronics that sullys the promise of USB-C.

It seems this spot welder is capable of doing the job, which is pleasing after our previous disappointing look at battery welders.

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Jana showing the board in action, with a magnetic probe attached to it

Add The Analog Toolkit To Your…Toolkit

January 3, 2024 by Arya Voronova 17 Comments

Analog acquisition tools are super helpful whenever you want to run an experiment, test out a theory, or improve upon your code, and you won’t realize how much you always needed one up until you’re facing a situation where it’s the only tool for the task. Well, here’s a design you might just want to add to your next PCB order — the STM32G4 Analog Toolkit from [Jana Marie].

The recommended STM32G431 is a wonderful tool for the task in particular. For a start, this board exposes nine 16-bit ADC inputs, with six of them capable of differential mode and three of them having the PGA (Programmable Gain Amplifier) feature. There’s also two 12-bit DAC pins, two timer outputs, three GPIOs, and UART with I2C for the dessert. As a bonus, it can work as a PD trigger, giving you higher-than-5V voltages out of USB-C for any experiments of yours.

The board requires only a few components, most of them easily solderable, with the STM32 in the TQFP32 package. The BOM is optimized, the GPIOs are used up to the max, with two spare GPIOs driving an RGB LED using a witty control scheme. There’s even a place to clip an alligator clip, in case that’s what your probing hardware wants! All in all, this is a carefully crafted design certainly worth having on hand.

Make sure to get a few of these made before you find yourself desperately needing one! That said, there’s always a backup option, the venerable ATtiny85.

Modern Control Of A Logic Analyzer

December 27, 2023 by Al Williams 8 Comments

When you think of a logic analyzer today, you might think of a little USB probe that can measure a few signals and decoding for various serial buses. But actual logic analyzers were high-speed multichannel hardware with sophisticated ways to clock and trigger. [Tom] picked up an HP1670G on the surplus market and was impressed that it could sample 136 channels at 500 MHz. The circa-2000 machine has a front panel, but if you really wanted to use it, you wanted to use an X terminal. [Tom] shows us how that works with modern Linux software.

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Talking Ohmmeter Also Spits Out Color Bands For You

December 24, 2023 by Lewin Day 13 Comments

If you’ve got a resistor and you can’t read the color bands (or they’re not present), you can always just grab a multimeter and figure out its value that way. [Giacomo Yong Cuomo] and [Sophia Lin] have built an altogether different kind of ohmmeter, that can actually spit out color values for you, and even read the resistance aloud. It’s all a part of their final project for their ECE 4760 class.

The build is based around a Raspberry Pi Pico. It determines the value of a resistor by placing it in a resistor divider, with the other reference resistor having a value of 10 kΩ. The resistor under test is connected between the reference resistor and ground, while the other leg of the reference resistor is connected to 3.3 V. The node between the two resistors is connected to the Pi Pico’s analog-to-digital converter pin. This allows the Pico to determine the voltage at this point, and thus calculate the test resistor’s value based on the reference resistor’s value and the voltages involved.

A large fake resistor provides user feedback. It’s filled with addressable LEDs, which light up the appropriate color bands depending on the test resistor’s value. It’s capable of displaying both 3-band, 4-band, and 5-band color configurations. While six-band resistors do exist, the extra band is typically used for denoting temperature coefficients which can’t readily be determined by this simple test. It can also play audio files to announce the resistance value over a speaker.

It’s a neat project that surely taught the duo many useful skills for working with microcontrollers. Plus, it’s kinda fun — we love the big glowing resistor. We’ve featured some other fancy resistors before, too!

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DIY Pneumatic Actuator Does Great In Action

December 23, 2023 by Lewin Day 5 Comments

Pneumatic actuators can be powerful and fast, making them very useful for all kinds of mechanical jobs. [Michael Rechtin] decided that while he could buy them off-the-shelf, he preferred to see if he could make his own via 3D printing. Despite the challenges, he succeeded!

Part of his success is because he knew when to take advantage of the strengths of 3D printed parts, and where they wouldn’t perform so well. To that end, the main body of the cylinder is actually a piece of PVC pipe. That’s because manufactured PVC pipe is far smoother and more regular than what you could reasonably achieve with a most 3D printers. The end caps, however, were printed and tapped to take standard air fittings. The piston was printed too, fitted with a steel cylinder rod and O-rings for sealing.

The double-acting cylinder performed remarkably well in testing, easily skewering an orange. The initial version did leak a touch, but later revisions performed better. Springs were also fitted for damping hits at either end which improved longevity, with a test rig racking up over 10,000 cycles without failure.

We love a design that is both easy to build at home and capable of great performance. We’ve featured some neat open-source pneumatic builds before, too.

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Ultra-Basic Thermal Camera Built Using Arduino Uno

December 22, 2023 by Lewin Day 17 Comments

Thermal cameras can cost well into the five-figure range if you’re buying high-resolution models with good feature sets. New models can be so advanced that their export and use is heavily controlled by certain countries, including the USA. If you just want to tinker at the low end, though, you don’t have to spend a lot of scratch. You can even build yourself something simple based on an Arduino Uno!

The build uses Panasonic’s cheap “Grid-EYE” infrared array as the thermal sensor, in this case, a model with an 8×8 array of thermopiles. It’s not going to get you any fancy images, especially at long range, but you can use it to get a very blocky kind of Predator-vision of the thermal radiation environment. It’s a simple matter of hooking up the Grid-EYE sensor to the Arduino Uno over I2C, and then spitting out the sensor’s data in a nice visual form on a cheap TFT screen.

It’s a great introduction to the world of thermal imaging. There’s no better way to learn how something works by building a working example yourself. We’ve featured a few similar projects before, too; it’s all thanks to the fact that thermal sensors are getting cheaper and more accessible than ever!

Hacker Tactic: Internal ESD Diode Probing

December 14, 2023 by Arya Voronova 15 Comments

Humans are walking high voltage generators, due to all the friction with our surroundings, wide variety of synthetic clothes, and the overall ever-present static charges. Our electronics are sensitive to electrostatic discharge (ESD), and often they’re sensitive in a way most infuriating – causing spurious errors and lockups. Is there a wacky error in your design that will repeat in the next batch, or did you just accidentally zap a GPIO? You wouldn’t know until you meticulously check the design, or maybe it’s possible for you to grab another board.

Thankfully, in modern-day Western climates and with modern tech, you are not likely to encounter ESD-caused problems, but they were way more prominent back in the day. For instance, older hackers will have stories of how FETs were more sensitive, and touching the gate pin mindlessly could kill the FET you’re working with. Now, we’ve fixed this problem, in large part because we have added ESD-protective diodes inside the active components most affected.

These diodes don’t just help against ESD – they’re a general safety measure for protecting IC and transistor pins, and they also might help avoid damaging IC pins if you mix. They also might lead to funny and unexpected results, like parts of your circuit powering when you don’t expect them to! However, there’s an awesome thing that not that many hackers know — they let you debug and repair your circuits in a way you might not have imagined.

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