This 80's circuit uses a germanium transistor like the AC121. The circuit has an output transformer of the type found on many transistor radios of the time.
This circuit is from a 1998 Poptronics. The circuit triggers a buzzer after a certain time, waking...
An integrated circuit 741 (operational amplifier is the basis of this voltage indicator, which can also...
This transistorized voltage converter is one of the oldest that we find in technical publications. It...