We found this circuit in Radio Electronics Special Projects from 1992. The circuit turns on the power when the microphone plug is inserted into the input jack.
With the components indicated, the circuit oscillates at 20 MHz. The coils and capacitors can be...
We found this preamplifier circuit with high input resistance, on the order of 30 M ohms, in an...
This symmetrical 1.2 to 35 V source was found in a 1994 documentation. The integrated circuits are...