Use a Classic Ding-Dong Bell With a Novel Modification to Activate Another Wireless Bell. Ringing Two Bells With One Switch and Added Range Extension

I have a classic Ding-Dong door bell which can be heard over most parts of my house. However in my workshop area the sound is faint and cannot be heard above the noise of machinery in use. I was looking for a method to install another bell in the workshop area without adding any additional wiring. A further constraint was that both bells should operate with the same switch.

I found a simple solution to this problem by using the solenoid within the Ding-Dong bell to activate the Transmitter of the Wireless bell as follows:

Winding a few turns of enameled copper wire the Ding-Dong Bell solenoid generates a short duration AC voltage on this winding, through transformer action, when the Bell-Push-Button is activated. When rectified and filtered this forms the supply to a standard Wireless Bell Transmitter Switch. When wired to transmit on Power Available it activates the Remote Wireless Bell.

This method of 'Relaying' the Ding-Dong Bell button-push to operate another Wireless Bell is a novel method of operating two bells with a single button-push and also extending the range to other remote locations.

The pictures show the inside of the Ding-Dong bell and details of the solenoid over which the enameled copper wire is wound.

*Note that the scheme is quite safe as we are not dealing with the mains voltage directly and only with a voltage derived on a secondary coil which is isolated by the transformer action of the solenoid coil.

Anchor Ding-Dong Door Bell

Anchor Wireless Door Bell

The Wireless bell Transmitter Switch operates with a 12V battery. I decided to work on a design with a operational voltage of approximately 7~8 volts.

I initially did a 50 turn test to determine the output turns/volt for the solenoid when operated as a transformer with the plunger fully inserted within the coil.

To get ~8 volts a secondary winding of 615 turns would be required this is also limited by the space available to accommodate the additional turns over the existing bobbin.

*Such a large number of secondary turns is required because the solenoid with secondary winding is not a ideal transformer as the magnetic path is not closed. The transformer action is purely based on mutual inductance and leakage flux.

I was able to wind 600 turns of #38 gauge enameled copper wire onto the existing bobbin.

I then fitted this into the existing mounting housing within the Ding-Dong bell

Pictures show the wireless transmitter switch circuit board.

I removed the battery clips and added a FR107 diode with a 100uF 25V capacitor to the battery connection points.

This would act as a half wave rectifier and filter for the voltage derived from the secondary coil.

Additionally I shorted the terminals of the small switch.

With this arrangement the card would transmit a signal to the wireless bell receiver as long as power is available.

This suits the requirement as voltage would only be developed in the secondary coil when the Ding-Dong bell solenoid is active. Power would be available only for a short duration acting to switch ON the wireless bell.

600 turns of #38 gauge wire when rectified and filtered provided ~7 volts DC for operating the transmitter.

Based on the instructions on pairing/synchronizing the transmitter and receiver on the wireless bell I added an external coaxial connector to feed the card through an isolation diode. To be used if necessary.

The video shows the operation of the scheme.

When the Ding-Dong bell is activated the solenoid plunder is pulled in and released.

Two things happen: First the Ding-Dong bell rings and simultaneously a signal is sent to the Wireless Bell which also emits a ringing tone.