Call Acknowledged!

This circuit could be used (depending on your circumstances) by a gentleman to summon his butler, a manager his secretary or as in the author's case to call the kids down to dinner without having to shout above the level of the CD player/TV/games console in their bedroom. Rather than resorting to a full-blown intercom system, a simpler solution was envisaged and while a buzzer could easily fulfill this function, this circuit has the advantage of providing a visual indication of a call as well as confirming to the caller that the ‘message’ has been received.