This power step drains just 3.5 mA from the battery and can provide good playback on a 4-ohm speaker. The circuit is from an 80's documentation.
Texas Instruments has downloadable documentation on designing digital isolators. The Digital...
This old AM receiver with an integrated circuit came out in a documentation from the 80s. The...
This simple circuit serves to demonstrate the working principle of a Set-Reset flip-flop (S-R or...