This circuit was obtained from a General Electric publication from the 1960s. The transistors are from the time and the circuit produces a 1 kHz signal with 1 V input.
This small crystal microphone transmitter was indicated in an 80s spy book. The range depends on...
The figure shows how to use an operational amplifier with a low impedance head. The gain is...
Voltage comparators, such as those in the LM139/239/339 series, consist of devices that can be...