This transistorized stage has a high gain, being adjusted by VR1. The circuit can be used as an excellent audio preamp. We found this circuit in a 1996 English publication.
This circuit triggers a relay when the detected humidity falls below a value. The system can be...
We found this circuit in an old General Electric documentation. In fact, PUTs are not common...
This alarm circuit was found in a 1997 publication. It uses two reed-switches to arm and disarm the...