Based on Radio Shack 276-137, this circuit was found in the December 1995 issue of Electronics Now magazine. The circuit drives an LED but could use a relay instead.
This amplified speaker is from a Radio Electronics from September 1988. The power integrated...
Found in a 90s American documentation, this circuit is used in vehicles with contact breaker. The...
This complete single cell protection system is suggested by Linear Technology in its 2005 manual....