This sonic key or vox was found in old English documentation. The operational admits equivalent as well as the transistors. The microphone is crystal.
Found in a 1966 documentation, this “coin finder” uses components from the era operating at 2.1...
This filter operates in the “opposite” way to the previous one (CIR8814), cutting all signals...
In the figure we have the way to use a stepper motor as an encoder. Operational amplifiers can be of...