This circuit was found in a 90s Wels' Think Tank. The frequency depends on C2 and R3. The handset or speaker must be at least 80-ohm. Observe the low supply voltage.
This circuit has a high input impedance and low output impedance, serving as an adapter for...
We found this simple warning circuit for car blinkers (arrow) in a 1987 publication. The relay must...
This 1987 circuit has a very interesting concept. It powers a second set of rhythmic lights from...