This sonic key or vox was found in old English documentation. The operational admits equivalent as well as the transistors. The microphone is crystal.
In the figure we have the typical configuration of a sinusoidal audio oscillator with twin-T. The...
This circuit was found in a 1969 US documentation. It provides a signal that can be externally...
We found this adapter in a 1970s American documentation on instrumentation. It is suitable for analog...