On: Crazy Circuits: An Open Source Electronics Learnin...

[tlrobinson]

Actually... https://www.bricklink.com/v2/catalog/catalogitem.page?P=4758...

Before Mindstorms there was a 9V system. It was really basic though: batteries, lights, motors, sirens, and wires.

[fenwick67 → tlrobinson]

The Mindstorms RCX used that same contact system and had light, rotation, and touch sensors as well.