This Kirlian machine circuit uses a car ignition coil. The circuit is from a Radio Electronics from May 1986. It is mentioned in an article that teaches how to obtain photographs.
This circuit uses a JFET CA3140 operational amplifier to convert a low frequency sinusoidal signal...
This commercial radio for the AM band was sold in Japan in the 1960s. The circuit has an IF of 455...
In the figure we have a simple way to produce tone in a piezoelectric transducer. The frequency depends...