This circuit has the intensity of the signals controlled by the light that falls on the sensor. Note that it is not a frequency-controlled oscillator. Equivalent transistors can be used.
What differentiates this circuit from the previous one (CB12689E) is the non-need to use a...
This simple metal detector was found in a 1960 Sylvania transistor manual. The phone must be high...
Found in a 90s Popular Electronics this circuit has its gain given by R2. This component can be...