This circuit was found in a 90s Popular Electronics. It produces a muted tone similar to that produced by a bell. The signal must be applied to an amplifier.
The LM567 is a PLL tone decoder that can also be used as a double oscillator as shown in the...
Originally designed to analyze the shape of light pulses from a flash for photographic...
This interesting control circuit was found in an Electronics Now from 1988. Through it we can...