This sensitive motion sensor with inductive sensor was found in a 90s Elektor. The circuit uses only transistors to activate a buzzer.
The resistors in this circuit marked with * must be within 1% tolerance. The circuit is from the...
This amplifier with very high input resistance has variable gain and must be powered by a...
This regulator is equivalent to 2 AA batteries providing a 5 V output voltage. The circuit is from...