This circuit was found in a 90s Popular Electronics. It uses an LS3404 melody chip that has several recorded melodies and that is uncommon nowadays.
This circuit can be used as an amplifier for musical instruments or even with your cell phone. The...
This circuit, which can act as a shield, was found in a 1970s American documentation. The...
This timer produces a continuous sound at the end of the timer set in potentiometer RV1. The...