This interesting circuit found in American documentation generates a busy signal, without you having to take the phone off the hook if you do not want to answer. The components used are common.
The integrated circuit used in this 80's mixer is the LM301A. However the circuit can be used to...
We found this circuit in a Motorola documentation from 1978. The circuit is based on the LM324...
This old slide projector control circuit was found in an 80s Hands On. The circuit uses modern...