This circuit allows the use of an electret microphone with a 1.5 V source. We found it in the Encyclopedia of Electronic Circuits volume 5 from 1995.
In the figure we have the way to obtain an operational amplifier with FETs at the input, using a...
This circuit was found in a 1980s documentation. The low voltage circuit uses a PUT. Transistors can...
This circuit shows numbers I II and III when mounted on its side, depending on the position of the...