We found this circuit in a 1994 National Semiconductor technical documentation. The circuit can be adapted to operate with more modern equivalent operational amplifiers.
The microphone for this circuit, found in a 1967 Japanese documentation, must be ceramic or...
Found in a magazine 73 for radio amateurs, this circuit makes use of general purpose transistors and...
This circuit was found in Philips documentation from 1967. The circuit uses components of the...