This circuit from a Popular Electronics from the 90s uses a common optocoupler and a general-purpose transistor to control a sensitive relay that can be from 6 to 12 V.
This circuit was found in a General Electric documentation from 1965. The circuit is full wave for...
This is another quick adder that we found in an Electronic Design from the 80s. It also applies to...
This circuit uses two sensors that are placed at the intersection of a miniature railroad, causing the LED...