Wireless door bell connected to fire bell

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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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..

crutschow

Joined Mar 14, 2008
28,557
Is the 24V for the bell AC or DC?
what is the best way to start learning about electronics?
Go to "Textbooks" at the top of the page for starters.

Olpallix

Joined Oct 3, 2017
12
Hi Crutschow
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
28,557
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
10,139
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.

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?

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?

Dodgydave

Joined Jun 22, 2012
10,139
Testing would be easier to do, you can take pictures of the pcb, all you need is a dvm to check it.

crutschow

Joined Mar 14, 2008
28,557
can I use any dc 12v transformer or do the amps need a specific rating?
It needs to be rated for at least 25% more current than the fire bell requires.

Olpallix

Joined Oct 3, 2017
12
Would the speaker readings change as I increase the volume button. If so, relaying to the speaker might not be such a good idea?

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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

Olpallix

Joined Oct 3, 2017
12
I ment pcb board not oxbow

Anyway the only digital meter I have is. In the picture
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?

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Olpallix

Joined Oct 3, 2017
12
Anyone out there. Is it something I’ve said. Lol

crutschow

Joined Mar 14, 2008
28,557
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.

Olpallix

Joined Oct 3, 2017
12
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.
Thank you. I will do that. I’ll try to get a better meter from work.

Dodgydave

Joined Jun 22, 2012
10,139
Can you take note of the chip numbers or zoom in better pictures.

DickCappels

Joined Aug 21, 2008
8,169
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.

Olpallix

Joined Oct 3, 2017
12
Can you take note of the chip numbers or zoom in better pictures.
Hi

Hopefully those pictures are good enough. Thanks mate

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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