This circuit allows the use of an electret microphone with a 1.5 V source. We found it in the Encyclopedia of Electronic Circuits volume 5 from 1995.
This sole beacon which has a battery charged by photocells was found in documentation from 1991....
This circuit uses a piezoelectric transducer to produce sounds like a buzzer. Frequency is...
This circuit activates a relay when the conducting bars (probes) are held by a person. The circuit is...