This crystal oscillator generates a 20 MHz signal. Equivalent transistors such as BF494 and 2N2222 can be used. The stabilizing diodes can be 1N4148.
This regulator type series for charging batteries from solar panels was found in a technical...
We can use high value electrolytic capacitors in alternating current circuits with the...
We found this circuit in an old French documentation from the 70s, but it can be assembled using...