When the voltage in the circuit exceeds the value set in the trimpot, the LED goes off and, if a low current buzzer is used, it rings. The circuit is from American documentation from 1999.
This circuit doubles the frequency of an audio signal, thus changing its timbre. The circuit was...
This circuit was obtained in a Radio Shack documentation from 1977. The sensor must have a...
This circuit was found in a Popular Electronics from the 90's. The circuit's waveforms are given,...