This circuit operates at a voltage of 1.3 V from a single mercury cell. We found in an old documentation and for the components used the frequency is 500 kHz.
This primitive solar radio was found in a Gernsback publication from 1960. The transistor is made...
We found this circuit in a 1995 documentation. It drives 4 sets of colored incandescent lamps that...
The small transmitter shown in the figure can generate signals in the range of 50 MHz to 200 MHz....