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.
The L1 coil is formed by 5 turns of 16 AWG wire in the form of 4 cm without core. Capacitors are...
Found in RCA documentation two years 70, this circuit triggers an incandescent lamp at dusk. The...
We found this circuit in a Popular Electronics of the 90s. Its purpose is to detect when it locks...