This is a typical circuit for an old microwave oven. We took it from an August 1973 Radio Electronics magazine, from an article that taught how to make repairs.
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...