This circuit was originally intended for reading movie soundtracks. The circuit is from 1967 and was found in an English publication. The sensor is semiconductor type.
Figure bellow shows how the flip-flops of a 4027 can be connected to perform a divide-by-5 counter [odd...
The basis of this 90s circuit is a CA3130 operational amplifier. The circuit does not need a...
With the indicated components, this circuit oscillates at 1232 Hz. Consider the tolerance of the...