This preamplifier for phonographic capsules using FET was found in 90s American documentation. Consumption is very low. The power can be obtained from the amplifier circuit with which it works.
Found in ancient American documentation, this circuit uses some components from the time, such as...
A JFET is used in this circuit to maintain constant gain. The circuit is from an Electronics Now...
This very low power amplifier is designed by Amperex for hearing aids. It is based on TAA370 which is...