We found this circuit in an 80's manual. The same configuration can be adapted to make use of modern operational amplifiers. The power supply is symmetrical.
This sensitive circuit detects the live pole of a power grid or outlet. The circuit makes use of a high...
This FET stage circuit was obtained from old American documentation but can be applied to any FET....
Found in old American documentation, this circuit can use crystals between 27.5 and 33 MHz...