The creator had a problem: the neighbours had exactly the same kind of doorbell as he did (actually a 50 Hz buzzer), so it used to ben’t always clear who wanted to reply to the door. To keep away from confusion, the writer augmented the present doorbell with a wireless edition a fairly cheaper possibility at current costs. All that was essential for this was once to organize for the present button and wiring to additionally actuate the wireless doorbell.
Circuit diagram :
Tandem Doorbell Circuit Diagram
The author unfolded the button enclosure of the wireless doorbell and used a multi-meter to search out out which set of contacts were closed when the button was pressed. This is the place the relay output should be linked (see the schematic diagram). The circuit is just about self-explanatory: when the prevailing doorbell button is pressed to actuate the buzzer, the voltage is rectified through the bridge rectifier and controlled at 5 V through the 7805. This voltage powers the relay in an instant, causing the switch within the wireless doorbell button to be shorted. As a result, together with the buzzer a huge Big Ben chime indicates that some-one is on the door. Now the writer simply hopes that hellos neighbour doesn’t replica his concept.
http://www.ecircuitslab.com/2012/05/tandem-doorbell.html
