This 3-step circuit for generating digital signals was found in the November 1976 issue of Radio Electronics magazine. The maximum frequency depends on the flip flops.
This circuit is from a Popular Electronics from the 90s. The integrated circuit admits equivalents...
This very interesting project was obtained in a 1980 publication. It consists of a device that is...
This circuit beeps when the sensor is triggered by the opening of the freezer door or other...