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.
This circuit drives two-color LEDs at a speed that is set in the 100k pot. The circuit can be...
The circuit shown was found in a 1967 RCA manual. Modern equivalent components can be used. The...
Indicated for automotive applications, this circuit was found in the November 1980 issue of Radio...