We found this preamplifier with 70 dB gain for microphones in American documentation from the 90's. Consumption is low and equivalent transistors can be used.
We found this oscillator in a publication for radio amateurs from the 70s. The circuit generates...
We found this circuit in a 1982 publication, but all the components used are still common in our...
We found this circuit in a 1976 technical documentation, but it can be assembled with modern...