This circuit mimics the heartbeat with the softest sound played through a small speaker. The circuit is from an Electronics Now issue of January 1997.
This counterphase circuit is from a 1973 publication, and can work with mains voltages or 12 V....
This circuit can be used to directly control direct current loads or higher alternating current loads...
The acquisition of data, from a transducer, so that these data can be converted to digital form...