This sequential circuit of LEDs was found in a Popular Electronics from the 90s. The circuit can be programmed and an adaptation consists of using optical couplers to drive power loads.
The integrated circuit used in this 1986 wireless microphone is not very common today. The L1 coil...
This circuit was found in Sprague Electric documentation from the 90s. The circuit uses a...
This version of mixed is one of the many that appears on the website using the 741. The circuit was...