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 circuit consists of a single Hartley oscillator using a bipolar transistor that can generate...
We found this circuit in a documentation about SCRs from the 70s. The circuit can be implemented with a...
This circuit was obtained in an old documentation, making use of an operational amplifier of the...