Editor’s note: This article will be in two parts. Part 1 is component-related and Part 2 is applications. Please also see Planet Analog blog “LEDs Are Photodiodes Too” as an intro to this article.

Arduino 101 is getting an LED to flash. From there you have a world of options for control, from MOSFETs to relays, solenoids and motors, all kinds of outputs. Here, we’re going to take a quick look ...

There are many ways to detect a heartbeat electronically. One of the simpler ways is to take [Orlando’s] approach. He’s built a finger-mounted pulse detector using a few simple components and an ...