We found this circuit in a Poptronics from the 90's. Equivalent operational amplifiers can be used. The circuit must be supplied by a symmetrical source.
This small telephone transmitter uses a telephone capsule as a microphone. The L1 coil has 4 to 5...
This circuit was found in an American documentation from the 1980s. The sensitivity ranges from...
This circuit produces a sinusoidal signal whose frequency can be calculated using the formula next...