Solar intercom (CB20503E)

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

Time Constant Multiplier (CB19498E)
This circuit multiplies a time constant given by the input components. The circuit admits...
Industrial alarm (CB23560E)
This circuit is nothing more than a powerful audio oscillator or buzzer with a power transistor. The...
Variable Frequency Ring Oscillator (CIR113E)
An way to change the frequency of the previous oscillator (CIR112E) is to add a variable capacitor in the...