This circuit was found in a 90s Popular Electronics. The sensors can be common speakers that reach from 15k to 25 kHz, such as piezoelectric tweeters.
This is a circuit with a period component that consisted of a voltage reference. The circuit is...
This experimental circuit was found in a technical publication from 1976. The diode can be of...
Tone controls for audio applications can also be considered filters that must attenuate certain...