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by DaxTrajero
Sat Aug 08, 2020 3:32 pm
Forum: Beginners
Topic: bit of advice please - simply sense a doorbell press
Replies: 22
Views: 983

Re: bit of advice please - simply sense a doorbell press

Thanks for all the ingenious ways this can be done, really appreciate it in terms of a non-invasive approach, I was intrigued by the current sensor option - that is, to place a current sensor clamp around the wire in the doorbell circuit - this appeals as the transformer is up in the loft and out of...
by DaxTrajero
Fri Aug 07, 2020 2:03 pm
Forum: Beginners
Topic: bit of advice please - simply sense a doorbell press
Replies: 22
Views: 983

Re: bit of advice please - simply sense a doorbell press

Ok. Try connecting one side of the bell to Pi ground (0V), the other through a series diode and resistor to a parallel capacitor, then on to the HAT input. Component values are not critical and may need experimentation. bell.jpg Thank you all for the informative comments! So, I already own the Auto...
by DaxTrajero
Fri Aug 07, 2020 12:19 pm
Forum: Beginners
Topic: bit of advice please - simply sense a doorbell press
Replies: 22
Views: 983

Re: bit of advice please - simply sense a doorbell press

What are you trying to achieve? You need to process a button press, but do you need to trigger the doorbell without a button press? It can be done, but the transformer output is probably AC, so some extra circuitry may be necessary (the website doesn't make it clear). I simply need to detect when s...
by DaxTrajero
Fri Aug 07, 2020 12:08 pm
Forum: Beginners
Topic: bit of advice please - simply sense a doorbell press
Replies: 22
Views: 983

bit of advice please - simply sense a doorbell press

Hello everyone I'd like some advice as to whether my PI Zero W equipped with a Automation HAT Mini from Pimoroni could detect a simple doorbell press? That's all I need - to sense the doorbell press. My doorbell is a convention model, some 20 years old, and utilises a 8VAC / 1A transformer, a chime ...
by DaxTrajero
Thu Aug 23, 2018 8:05 pm
Forum: Beginners
Topic: Relay - can it be used in reverse (signal microcontroller) ?
Replies: 14
Views: 1316

Relay - can it be used in reverse (signal microcontroller) ?

Newbie alert: Is it possible to use a mechanical relay that, when there's an AC voltage, switches the DC side of the relay? ie. someone turns on a light, and the raspberry pi is signalled

Or is the alternative to use a solid state opto-coupler and resistors?
by DaxTrajero
Fri Aug 10, 2018 9:22 pm
Forum: Beginners
Topic: How to detect an old style wired doorbell only - nothing else
Replies: 20
Views: 2370

Re: How to detect an old style wired doorbell only - nothing else

My doorbell uses a Pi. The long leads from the button are connected to the 5v from the pi and a resistor to drive the input of an opto-isolator. One side of the output stage of the opto is connected via a resistor to 3.3V and a GPIO. The other side is connected to ground. When the button is pressed...
by DaxTrajero
Fri Aug 10, 2018 3:45 pm
Forum: Beginners
Topic: How to detect an old style wired doorbell only - nothing else
Replies: 20
Views: 2370

Re: How to detect an old style wired doorbell only - nothing else

Thanks for all the info

As a future project, I wonder if its worth removing the chime box altogether...

Wire the doorbell button to the PI

Let the PI talk to something like an ECHO DOT to produce a chime?
by DaxTrajero
Fri Aug 10, 2018 3:33 pm
Forum: Beginners
Topic: How to detect an old style wired doorbell only - nothing else
Replies: 20
Views: 2370

Re: How to detect an old style wired doorbell only - nothing else

https://electrical.knoji.com/images/user/danmsnyder/doorbell-transformer-wiring-fbdaee2c.jpg Is the transformer could be ac or dc. Can you check? Basically you can connect and opto-isolator across the bell terminals and connect the output to a gpio. Connect it like a push button. Choose a series re...
by DaxTrajero
Fri Aug 10, 2018 3:31 pm
Forum: Beginners
Topic: How to detect an old style wired doorbell only - nothing else
Replies: 20
Views: 2370

Re: How to detect an old style wired doorbell only - nothing else

1. Don't try to put html code in your post. 2. It is unlikely that you can power the RPi from the existing bell transformer for several reasons: a. it may be outputting AC. b. even if outputting DC it is unlikely to be close enough to the 5 volts that a RPi requires. c. bell transformers are usuall...
by DaxTrajero
Fri Aug 10, 2018 2:21 pm
Forum: Beginners
Topic: How to detect an old style wired doorbell only - nothing else
Replies: 20
Views: 2370

How to detect an old style wired doorbell only - nothing else

(updated) Hi Everyone Just need a small bit of advice to get going. Not looking to fit any fancy camera/remote doorbell. Simply want to use a PI to detect when the old style wired doorbell button has been pushed. The wired doorbell button is wired to a chime in the hallway. There's two wires leading...

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