relaying door bell

[sender jones]

In a corner of my place I can only barely hear the door bell rings. It is a wired door bell with a press-to-make button outside wired to a musical door bell speaker insider. I am trying to add a wireless door bell to it so that when visitor press the ouside button, both bells ring. The wireless door bell has a trigger part and a speaker part. I tear down the enclosure of the trigger part, lead 2 wires from a press button inside it and connect them to the terminals of the wired door bell speaker. But then both bells keep on ringing even without pressing any button.

The wired bell speaker uses 3V battery and has 2 terminals, R & G, used to connect to the external button. Normally, R has 2.65V and G is grounded to the negative of the battery. The wrieless bell button uses 12V battery and the leads I added to its button are A & B. Normally A has 11.3V and B has 1.3V relative to its battery negative. With these I added a transistor and a resistor (jpg attached)
**broken link removed**
It works. But 2 problems:
1. If I touch G with my finger, the wired bell rings.
2. Though both bells ring when the external button is pressed, the musical tone of the wired bell is slower. Until the wireless bell finish ringing (wired bell rings longer than wireless bell), the musical tone will back to normal.

Please help me solve these 2 problems, or suggest a better solution. Thank you in advance.

 

[Diver300]

The resistor should probably be in series with the base instead of the emitter of the transistor. Also you should have a resistor between the base and emitter to stop very small currents turning on the wired bell, which is what seems to be happening when you touch point G.

However, with all the different voltages, especially the fact that neither A nor B are at 0 V when the switch is open, it might save a lot trouble to use a small double pole relay. The button would only operate the relay, and each contact of the relay would operate one doorbell. That would work for any type of bell that can use an external button, and it wouldn't matter what voltages there are. There is also no risk that a relay circuit would cause current to be taken from either battery while the button was not being pressed.

https://uk.farnell.com/2360793 if you want to run from the relay from the 12 V battery or https://uk.farnell.com/2360801 for the 3 V battery would be fine.

 

[audioguru]

My home was built with an American all-metal doorbell. It made a sound like "ding-dong" and was not loud enough.
I replaced it with a cheap Chinese one that had proper plastic acoustical resonant chambers over the vibrating bars and it is much louder and sounds like "DING-DONG".

 

[alec_t]

DING-DONG

Isn't that the manufacturer's name? .

 

[audioguru]

Isn't that the manufacturer's name?

Don't English names for Chinese companies say Bang and Gold? Golden Bang.
Chinese people cannot say our letter L so Ding-a-Ling will become Ding-a-Ring.

 

[sender jones]

Thank you Diver. I move the resistor to the base and put a relay in its place. Now they work as I expected.