With this circuit it is possible to receive and send audio signals simultaneously over the same telephone line. The circuit was found in an Elektor from the 90s. The power supply is symmetrical.
What differentiates the CIR8139 circuit is the use of two inverter ports to trigger the transistor that...
The battery charger suggested in the figure has its current limited by resistor R1. This component may...
This circuit with increased power output was found in the November 1974 Radio Electronics...