A coil with an iron core is called an electromagnet. The iron core increases the coil’s magnetic field strength. A simple electromagnet is made by coiling wire around an iron nail. An iron core ...

The one that [Made in Poland] chose to sacrifice was particularly nasty and greasy, but after popping off the pulley, the treasure within was revealed: the large, ring-shaped clutch electromagnet.

It’s an electromagnet pendulum analog circuit. Whether you’re building it, or just studying the schematics, this is a fun way to brush up on the non-digital side of the craft. The pendulum is ...