Based on the Linear Technology LTC2054, this -48 V circuit was found in a 2005 manual. The circuit is powered with 5 V and can be used as a shield.
We found this transmitter in 1980s documentation. Coil data is found next to the diagram and...
This very low power amplifier is designed by Amperex for hearing aids. It is based on TAA370 which is...
This circuit uses an impact sensor transistor called Pitran rare today. The circuit is from 1969...