This circuit is from the 80's but uses common components today. The relay is voltage sensitive according to the power supply used. Transistors may be general purpose types.
This simple oscillator with two general-purpose transistors has its frequency given by capacitor...
We found this circuit in the Linear Applications Handbook by National Semiconductor. The base is...
This is a very simple configuration with a power transistor to control a DC motor from 3 to 12 V...