This stereo meter-indicator was found in the August 1971 issue of Radio Electronics magazine. The transistors are known types and BC548 equivalents can be used.
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...