Amateur Scientist

Experimenting with Light and Dark SENSORS

Use photoresistors, phototransistors, and photodiodes to make simple, powerful sensors for your projects.

Written by Forrest M. Mims III


Gunther Kirsch

Time Required: 1–2 Hours

Cost: $10–$30

Easy, inexpensive circuits to give your projects sensitive “electric eyes.”

FORREST M. MIMS III (, an amateur scientist and Rolex Award winner, was named by Discover magazine as one of the “50 Best Brains in Science.” His books have sold more than 7 million copies.



Photoresistors, ...

Get Make: Technology on Your Time Volume 38 now with the O’Reilly learning platform.

O’Reilly members experience live online training, plus books, videos, and digital content from nearly 200 publishers.