This a POV (Persistence of vision) Display based on an Arduino Pro Mini clone.
Relays are electrically operated switches, which allow a low-level electrical signal to control a separate larger electrical voltage or current.
A relay is an electromechanical device that consists of a number of parts, including the Coil, core, armature, yoke, contacts, spring and the push-rod.
This is how to remove the high voltage camera flash pcb from a disposable camera. You can use this to revive nicad batteries, make sparks, electric shocks, mini taser, zap, zapper etc.
Warning – this circuit produces about 350 volts and could be dangerous in some circumstances.