For their final project in [Bruce Land]’s class on designing with PIC32 microcontrollers, [Sujith], [Julia] and [Andrew] wanted to do something fun. And what could be more fun than bending to the electromechanical siren song of the pinball machine?

This machine looks great, and as you can see in the demo video after the break, it plays and sounds great, too. We particularly like the boomerang obstacle and the game state-driven LED strip. The more points you score, the brighter they go. We also like that this machine combines traditional scoring methods with a few really clever ones, like the boomerang target near the top and the scoring triggers made from copper tape.

The team started by designing the heart of any pinball machine, the flippers. Though we have seen car door lock actuators used in homebrew machines, the team went with traditional solenoids to drive them. Unfortunately the solenoids caused a lot of interference, but the team got around it with filter capacitors and aluminium foil Faraday cages around the wires.

If all this pinball talk has your circuits lit up, why not try making your own machine?

source https://hackaday.com/2019/12/25/team-scores-big-points-with-pinball-final-project/

Sometimes, a project comes along that makes a good reference design for anyone doing similar work. In this particular case, it’s a DIY USB polygraph-like machine by [Juangg] using an Arduino and sensors on the hardware side, and a Python front end for data visualization. It’s even complete with 3D printed enclosure and sensor elements.

[Juangg] designed it to use three sensors: a pulse sensor, a breath sensor, and one to measure Galvanic Skin Response (GSR). The pulse sensor uses a piezo element pressed against a fingertip to detect changes in pressure resulting from blood flow. It can be picky about placement, but finding sweet spot can yield remarkably good readings. The breath sensor works on a similar principle but uses a 3D printed fixture to hold the sensor between a strap and the subject’s chest, so that breathing in and out can be detected. The GSR sensor is a voltage divider used to measure small changes in skin conductivity. How well does it all work? That depends on what one is looking to get out of it, but the documentation and design files are available from the project page and the GitHub repository if anyone wants a reference for similar work.

The polygraph may have a mixed reputation, but it makes a good project that demonstrates just how messy biometrics can be from an engineering perspective. And in case you missed it, here’s a reminder that Wonder Woman and the polygraph have much more in common than you might realize.

source https://hackaday.com/2019/12/25/arduino-polygraph-shows-how-its-done/