Found in American documentation from the 1980s, this circuit prolongs the ringing of a doorbell or chime powered by a 6 V continuous voltage. The transistor can be a BD136.
This adjustable circuit from 0 to 200 nA was found in a 90's EDN. The components can still be...
We found this circuit in 2005 Linear Technology documentation. MPOSFET is load-matched. The...
This circuit generates audio tones in a speaker with controlled frequency and volume. The...