This is a kit to build a mini waveform monitor similar to the one seen on YouTube, but could be applied to other signal capture projects as well. Design has been updated to correct the known defects on the original PCB (but see the note below about the audio jack signal). Designed for use with an STM32 Blue Pill and a 2.8" LCD module, but of course you can do with it as you like. It uses an op amp voltage follower for each of the three signals (one intended for waveform display, the other two intended for RMS calculations, but the software is open source). "Grounds" the signals at about the midpoint of the microcontroller board's voltage range to accomodate signals that go below signal ground (unlike the op amp offset approach of the Rospo board). You will therefore want to use this with a floating power supply.

Youtube video: https://youtu.be/TKOVB0_aJVE

This board is for LOW VOLTAGE ONLY. Do not connect it to your utility mains without proper isolation. It is intended for signals that stay within about +/- 1V of signal ground. The YouTube video is not intended to instruct you in connecting to any signals larger than this. Consult a qualified person if your signals are greater than +/- 1V. Bandwidth is also more limited than the Rospo kit (which is intended for more general signal capture) because this one needs an op amp suitable for use with a single-ended power supply, but as you can see in the video it still easily handles the 50-60 Hz waveforms used in electrical systems.

This is supplied as a kit of parts. You will need a soldering iron and solder in order to assemble it. You will also need to supply your own STM32 Blue Pill microcontroller board (along with the means to program it, such as an ST-Link). You can power this board over the USB connection on the Blue Pill, or by attaching 5V and GND to the provided screw terminals. If you are sensing AC current, you will probably want one or two current clamps with a 3.5mm jack at the end (I used SCT-013 clamps in the video). Note that the PCB assumes the signal is between the tip and the ring contacts, not the tip and the sleeve. Maybe this is why I have to not quite fully insert the plug for it to work for me, but connecting to tip and sleeve didn't seem to work right on my sensor clamps. So that's how I did it. Maybe you would want to try shorting the ring and sleeve together in your build -- if you do, let me know how it goes. One other signal to be monitored can be attached to provided screw terminals, for three channels total. If you choose to attach an LCD display, the PCB layout and provided sofware assume an ILI9341-based module using SPI with the typical pinout: VCC, GND, CS, RESET, DC, SDI, SCK, LED. (More pins are usually present after that, but this is the 1x8 section of the connector used in this build, which does not connect to the touch sensor or SD card reader that may be present on the display module.) I used a 2.8" display in the video.

Approximate board dimensions are 55 x 95 mm.

This is not a commercial grade product. It is a hobby kit simply meant to help you do hobby signal monitoring. Seller will try to provide basic technical support, but ultimately this is a DIY project and your results may vary.

Sample software, probably not bug-free: https://github.com/picosapiens/pwrmon

Supplied parts may differ somewhat from the photo.