Tandem Doorbell

The author had a problem: the neighbours had exactly the same type of doorbell as he did (actually a 50 Hz buzzer), so it wasn’t always clear who needed to answer the door. To avoid confusion, the author augmented the existing doorbell with a wireless model — a reasonably inexpensive option at current prices. All that was necessary for this was to arrange for the existing button and wiring to also actuate the wireless doorbell.