A clever and useful circuit for the driver. When you enter the car and the doors are closed it keeps the interior lights on for a few seconds to give you time to put the key in the lock, fasten your safety belt and start the car. The delay is adjustable. See and understand exactly how each works. Good introduction to electronics.
Oscillators are everywhere in electronics.
They are a basic building block upon which the whole structure of electronics and computers is based. This kit looks at the 3 basic types of multivibrators. In the flip-flop MV a trigger pulse or control signal is required to change from one state to the other. These circuits have now largely been replaced by timer ICs like the 555. However, a basic understanding of them is still essential since they are still used in many circuits.