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.
This 3-channel transmitter for amateur analog TV from 902 to 908 MHz was found in a QST magazine...
The MC1455 integrated circuit consists of a version of the 555 made by Motorola. The circuit given...
The figure shows how to use the LM3900 to drain current from a load of up to 20 mA with the...