Solar intercom (CB20503E)

This circuit can be used in demonstrations or science fairs. The circuit uses headphones and can be powered by solar cells.

4-Tone Oscillator (CB21115E)
Using 4 operational amplifiers this circuit generates 4 different tones. The circuit is from an...
Positive or Negative Voltage Doubler (CB1229E)
In the figure we have an application of an oscillator 4013 as voltage multiplier. It consists of a...
10 to 84 MHz Colpitts oscillator (CB4052E)
This Colpitts crystal oscillator was found in an American publication for amateurs in the 1980s....