Found in older Signetics documentation, this circuit generates signals from 30 Hz to 25 kHz. Operational amplifiers are from the time, as is the matching pair of transistors.
Placed near a telegraphic transmitter (CW) and with a small antenna or pickup, it reproduces the...
The LM387 integrated circuit used in this project is not very easy to obtain. The circuit, from an...
The recommended distance between the emitter and the sensor of this coupler is 15 mm. The circuit is...