Found in a 303 Circuits from the 90's this circuit can use the lowest current range of a common multimeter. The circuit can measure currents as low as 100 pA.
This powerful amplifier was part of commercial sound circuits from the 90s. The integrated circuit...
This circuit generates a control tone that serves to adjust amplifiers, check audio cables. The...
This circuit locks when the sensors are opened. The relay can be 6 or 12 V depending on the power...