kaushikkyle
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Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 12:22 pm

Hello,
(Total noob question, avoid my stupidity if any)
I am planning to make a smart doorbell which is connected to an already existing normal AC powered doorbell system (just a bell switch and a doorbell) , I want to connect the wire from the switch to both my bell as well as the GPIO of my raspberry pi , which component , like resistor or relay , should i connect the wires then connect it to the raspberry pi? Is my idea possible? All the other DIY projects specify having an individual button switch for the raspberry pi,if possible how to detect when a current passes through?
Thanks

scotty101
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Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 12:27 pm

Standard "AC voltages can be dangerous, only work with them if you are qualified" warning.

A relay would likely be the most suitable. You'll need to find one that works with the voltages output by the doorbell circuit.
The relay's coil should be connected in parallel with the doorbell and you can use relay's switch terminals to act like any other switch on a GPIO pin.
There are other options but I'd say a relay is the best given the isolation between the two circuits and the simplicity of the circuit required.
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kaushikkyle
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Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 12:32 pm

scotty101 wrote: Standard "AC voltages can be dangerous, only work with them if you are qualified" warning.

A relay would likely be the most suitable. You'll need to find one that works with the voltages output by the doorbell circuit.
The relay's coil should be connected in parallel with the doorbell and you can use relay's switch terminals to act like any other switch on a GPIO pin.
There are other options but I'd say a relay is the best given the isolation between the two circuits and the simplicity of the circuit required.
Thanks for the quick reply.

Andyroo

Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 12:48 pm

I’m really surprised that the doorbell would be at mains voltage. Are you sure there is not a transformer dropping the voltage to 12v?

kaushikkyle
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Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 12:58 pm

Andyroo wrote:
Wed Sep 04, 2019 12:48 pm
I’m really surprised that the doorbell would be at mains voltage. Are you sure there is not a transformer dropping the voltage to 12v?
Yeah , the doorbell works at main voltage and there is not any transformer or any other device dropping the voltage , am guessing there might be something like that internally in the bell.

pcmanbob
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Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 1:35 pm

kaushikkyle wrote:
Wed Sep 04, 2019 12:58 pm
Yeah , the doorbell works at main voltage and there is not any transformer or any other device dropping the voltage , am guessing there might be something like that internally in the bell.

Guessing when working with mains voltage is a sure way to get yourself or someone else killed or to start a fire.

if you don't have any electrical training seek help from a qualified professional.
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kaushikkyle
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Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 2:12 pm

pcmanbob wrote:
Wed Sep 04, 2019 1:35 pm
kaushikkyle wrote:
Wed Sep 04, 2019 12:58 pm
Yeah , the doorbell works at main voltage and there is not any transformer or any other device dropping the voltage , am guessing there might be something like that internally in the bell.

Guessing when working with mains voltage is a sure way to get yourself or someone else killed or to start a fire.

if you don't have any electrical training seek help from a qualified professional.
The doorbell was installed by an well experienced electrician , Am just gonna prep the code on the raspberry pi and surely will ask an electrician to connect it , I just guessed there might be some internal component in the bell which steps down the voltage. Anyways Thanks for the advice tho.

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Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 2:16 pm

Andyroo wrote:
Wed Sep 04, 2019 12:48 pm
I’m really surprised that the doorbell would be at mains voltage. Are you sure there is not a transformer dropping the voltage to 12v?
You can't have an outdoor bell push at more than 48V (SELV) there'd be too much risk of electrocuting the postie. My doorbell runs at 16V AC.
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kaushikkyle
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Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 2:22 pm

DougieLawson wrote:
Wed Sep 04, 2019 2:16 pm
Andyroo wrote:
Wed Sep 04, 2019 12:48 pm
I’m really surprised that the doorbell would be at mains voltage. Are you sure there is not a transformer dropping the voltage to 12v?
You can't have an outdoor bell push at more than 48V (SELV) there'd be too much risk of electrocuting the postie. My doorbell runs at 16V AC.
I can understand , but its pretty much common in the place where am living . I'll do something about it then, Thanks for the advice.

Fraoch
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Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 3:04 pm

DougieLawson wrote:
Wed Sep 04, 2019 2:16 pm
Andyroo wrote:
Wed Sep 04, 2019 12:48 pm
I’m really surprised that the doorbell would be at mains voltage. Are you sure there is not a transformer dropping the voltage to 12v?
You can't have an outdoor bell push at more than 48V (SELV) there'd be too much risk of electrocuting the postie. My doorbell runs at 16V AC.
It's the same in North America as well, full AC voltage is just too dangerous to pass through a flimsy plastic doorbell button exposed to the elements. It's 16 VAC here too.

I'm not sure where the OP is, but they almost certainly have a transformer somewhere.

https://diyhousehelp.com/doorbell-wiring-diagrams
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kaushikkyle
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Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 3:08 pm

Fraoch wrote:
Wed Sep 04, 2019 3:04 pm
DougieLawson wrote:
Wed Sep 04, 2019 2:16 pm
Andyroo wrote:
Wed Sep 04, 2019 12:48 pm
I’m really surprised that the doorbell would be at mains voltage. Are you sure there is not a transformer dropping the voltage to 12v?
You can't have an outdoor bell push at more than 48V (SELV) there'd be too much risk of electrocuting the postie. My doorbell runs at 16V AC.
It's the same in North America as well, full AC voltage is just too dangerous to pass through a flimsy plastic doorbell button exposed to the elements. It's 16 VAC here too.

I'm not sure where the OP is, but they almost certainly have a transformer somewhere.

https://diyhousehelp.com/doorbell-wiring-diagrams
I'm from India , I have verified with my dad(who is an electrical engineer ) and he had inspected all the electrical connections in my house when it was being built ,No such transformer or device has been installed. :|
Thanks for the link, i'll make my dad install a transformer.

Fraoch
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Location: Cambridge, Ontario, Canada

Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 3:19 pm

kaushikkyle wrote:
Wed Sep 04, 2019 3:08 pm
Fraoch wrote:
Wed Sep 04, 2019 3:04 pm
DougieLawson wrote:
Wed Sep 04, 2019 2:16 pm


You can't have an outdoor bell push at more than 48V (SELV) there'd be too much risk of electrocuting the postie. My doorbell runs at 16V AC.
It's the same in North America as well, full AC voltage is just too dangerous to pass through a flimsy plastic doorbell button exposed to the elements. It's 16 VAC here too.

I'm not sure where the OP is, but they almost certainly have a transformer somewhere.

https://diyhousehelp.com/doorbell-wiring-diagrams
I'm from India , I have verified with my dad(who is an electrical engineer ) and he had inspected all the electrical connections in my house when it was being built ,No such transformer or device has been installed. :|
Thanks for the link, i'll make my dad install a transformer.
Wow, well if you have the resources of an electrical engineer at your disposal, then by all means take advantage. :)

You may not necessarily need a transformer as a relay can operate at full household AC voltage no problem, but those voltages are dangerous. This is not a "do it yourself" thing, you need equipment with the proper rating and someone qualified to work on it.
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kaushikkyle
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Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 3:26 pm

Fraoch wrote:
Wed Sep 04, 2019 3:19 pm
kaushikkyle wrote:
Wed Sep 04, 2019 3:08 pm
Fraoch wrote:
Wed Sep 04, 2019 3:04 pm


It's the same in North America as well, full AC voltage is just too dangerous to pass through a flimsy plastic doorbell button exposed to the elements. It's 16 VAC here too.

I'm not sure where the OP is, but they almost certainly have a transformer somewhere.

https://diyhousehelp.com/doorbell-wiring-diagrams
I'm from India , I have verified with my dad(who is an electrical engineer ) and he had inspected all the electrical connections in my house when it was being built ,No such transformer or device has been installed. :|
Thanks for the link, i'll make my dad install a transformer.
Wow, well if you have the resources of an electrical engineer at your disposal, then by all means take advantage. :)

You may not necessarily need a transformer as a relay can operate at full household AC voltage no problem, but those voltages are dangerous. This is not a "do it yourself" thing, you need equipment with the proper rating and someone qualified to work on it.
Ohhh...okay.....Sure will do....Thanks

PhatFil
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Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 4:09 pm

What sort of bell is being rung by the doorbell?? IF its a mechanical bell and hammer you may be able to wire a passive circuit using a magnet superglued to the bell hammer with a reed switch or similar to detect the magnets movement and ringing of the bell..

same result but no need ti get involved with mains voltage circuits,

kaushikkyle
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Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 4:15 pm

PhatFil wrote:
Wed Sep 04, 2019 4:09 pm
What sort of bell is being rung by the doorbell?? IF its a mechanical bell and hammer you may be able to wire a passive circuit using a magnet superglued to the bell hammer with a reed switch or similar to detect the magnets movement and ringing of the bell..

same result but no need ti get involved with mains voltage circuits,
No it is not a mechanical bell, its a electrical bell. as mentioned above i'll try with a relay

drgeoff
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Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Wed Sep 04, 2019 10:06 pm

kaushikkyle wrote:
Wed Sep 04, 2019 2:12 pm
The doorbell was installed by an well experienced electrician , Am just gonna prep the code on the raspberry pi and surely will ask an electrician to connect it ,
95% of electricians* have no idea of how to interface a doorbell (AC, DC, low voltage or not) to a RaspberryPi. The 5% that do is because of hobby interest, not professional training.

* electrician in this context being the genre of tradesman who installs electrical wiring, fuseboxes, socket outlets etc. I'm not denigrating the skills and qualifications involved for that. Just that rather different ones are required.

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Burngate
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Re: Connecting existing Doorbell (AC door bell with bell switch ) to raspberry pi 3 GPIO

Thu Sep 05, 2019 9:06 am

I don't suppose you could post some details of this doorbell - make, model, etc. - and maybe pictures of what's inside it?
We can all guess what it should be like, but reality often surprises us.

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