Wireless door bell connected to fire bell

Thread Starter

Olpallix

Joined Oct 3, 2017
12
Hi sorry to jump in like this, as this the first day I registered.
I am clueless to circuitry but always told myself it's something I would like to get into. Thought I'd start with circuit bending maybe one day
However, today I a simple matter I'm sure sir all of you I believe

I have a wireless door belle that has 2volt push button activator at the the from door. Not drawn in my ridiculous diagram.
And a 240v receiver at the other end plugged into a socket.
I wanted to use the signal coming out from wires connect to speaker to complete the circuit of a 24v bell without blowing up any of the receivers internals, so my question is how do you do that by implementing some sort of circuitry along the way, I hope my silly diagram makes sense.
Thanks for having a look
It's for a nice outbuilding I built for my back garden, I'm a cabinet maker by trade ;)
 

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Thread Starter

Olpallix

Joined Oct 3, 2017
12
Oh. And by the way, what is the best way to start learning about electronics? Any great youtube teachers out there?
Sorry about all my previous typos, new I shouldn't have posted this from my journey back on the train..
 

Thread Starter

Olpallix

Joined Oct 3, 2017
12
Hi Crutschow
Thanks for your interest and quick reply
It says it 12/24v dc I think if I had to chose id go for 12v

Thanks for textbooks I’ll look it up. Looking forward to it
Cheers.
 

crutschow

Joined Mar 14, 2008
28,155
You need to measure the AC voltage across the speaker terminals.
That AC voltage will then need to be rectified to DC and amplified to turn the bell on and off.

The 24V transformer you show can be a 12Vdc wallwart supply.
 

Dodgydave

Joined Jun 22, 2012
10,082
Chances are there will be a pin on the receiver chip that goes high or low that you can use to drive a transistor to work the relay for your bell.
 

Thread Starter

Olpallix

Joined Oct 3, 2017
12
You need to measure the AC voltage across the speaker terminals.
That AC voltage will then need to be rectified to DC and amplified to turn the bell on and off.

The 24V transformer you show can be a 12Vdc wallwart supply.
Cool. I’ll measure the voltage tomorrow. Thank you.. can I use any dc 12v transformer or do the amps need a specific rating?
 

Thread Starter

Olpallix

Joined Oct 3, 2017
12
Chances are there will be a pin on the receiver chip that goes high or low that you can use to drive a transistor to work the relay for your bell.
Hi Dodgydave... could you tell from a picture or would I need to do some testing to find the correct pin?
 

Thread Starter

Olpallix

Joined Oct 3, 2017
12
Also. I have one concern about f welding to oxbow directly. As a be done this before and all though I thought I hadn’t done any damage. The board had stopped working. Or more to the point I must of closed a circuit somewhere and it kept on working. I have a cheap soldering iron. And i put flux but still find it hard to do properly I guess
 

crutschow

Joined Mar 14, 2008
28,155
What setting should I put it on to test speaker? And do I need to press the Bell button for a reading. Or when off?
You set the meter to 200~(AC).
Yes, you press the Bell.
But that meter is rather insensitive, so the reading will likely be quite low, in the neighborhood of a couple volts.
 

DickCappels

Joined Aug 21, 2008
7,953
A great many of the inexpensive wireles doorbell receivers use transformerless power supplies. In that case, the doorbell signal is not isolated from the power line and connecting to it might result in damage to the rest of your system and maybe you.

Do you know whether your doorbell receiver is isolated from the line?

You can check by measuring from the output to ground. Reverse the plug in the wall and measure again. If you see something like line voltage with either plug orientation you will need to add some additional isolation. Perhaps an optical isolator at the doorbell ouput of a 1:1 isolation transformer at the input.

If you measure next to noting with both orientations of the plug things are fine and you don't need extra isolation.
 

Thread Starter

Olpallix

Joined Oct 3, 2017
12
A great many of the inexpensive wireles doorbell receivers use transformerless power supplies. In that case, the doorbell signal is not isolated from the power line and connecting to it might result in damage to the rest of your system and maybe you.

Do you know whether your doorbell receiver is isolated from the line?

You can check by measuring from the output to ground. Reverse the plug in the wall and measure again. If you see something like line voltage with either plug orientation you will need to add some additional isolation. Perhaps an optical isolator at the doorbell ouput of a 1:1 isolation transformer at the input.

If you measure next to noting with both orientations of the plug things are fine and you don't need extra isolation.
Thanks for your reply. Do you mean reversing polarity of the 240v. Sounds scary!! But if I have to I’ll do it
 
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