This 555-based circuit was found in the August 1976 issue of Radio Electronics magazine. The tone frequencies are provided by the capacitors connected to the 555 IC.
This PWM circuit was found in an American publication from 1978. It consists of a simple control that...
This circuit, from an old ON Semiconductor publication, suggests a shield to excite an LED from an...
The integrated circuit used in this application is not currently common. The circuit is from 80s...