Picture of Doorbell to Arduino 'Interface'
Hi Everybody
In my first Instructable I want to show you how to build an cheap and easy Doorbell to Arduino 'Interface' so you can let your Arduinoproject get triggered through it or simply use your Arduino as a bell.

Almost endless possibilities :D
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Step 1: What you need...

Picture of What you need...
Here's what you'll need, its not that much...^^

First of all you need the 'heart' of the interface, the relay.
-My Doorbell has 12V DC so I used a FTR F1CA012V which is a 'Double Pole Single Throw'-relay but you can use 'Normally-open' or 'Change-over'-relays as well.

You also need:

1x 100k Ohm Resistor

1x small 3 port luster terminal

some bell wire

about 20cm control wire cable

shrink tubes to isolate the contacts and protect the 'Interface'

soldering tools

Thats it!

Step 2: Lets build...

Picture of Lets build...
Ok, lets Build the Interface.

- solder the bell wire to the relay coil connections and isolate the contacts with shrink tube

- solder one single control wire (red) to the relay common terminal and isolate the contact with shrink tube

- prepare an other control wire (black), take the resistor and solder it to one end

- solder a third control wire (yellow) and the black wire with the pull up resistor to the relay 'normally-open' terminal, take some shrink tube and isolate the contact all over the resistor

- cut off a ~10-14cm long piece from the control wire cable isolation, pull your 3 control wires through it and insert them into the luster terminal

- at last do a big piece shrink tube and shrink in the whole relay with the cables to protect them from getting broken.

Here it is! Your very own Doorbell to Arduino 'interface'

... go on to see how to install and use it...
kInstructor3 years ago
You forgot the diode. You MUST put a diode in parallel to the relay, elsewhere a current flows backwards when the relay is going off, which can damage the arduino!!!
Michelangelclone (author)  kInstructor3 years ago
Thanks for your response :)
Do you mean that current will flow from the GND to the Arduino I/O pin if there's a positiv current on GND and the relay 'off' respectively if there's a higher current on GND as on Vcc it will flow into Vcc?!
I thought about it too but it wasn't treated yet :( Doesn't the pull up resistor do the job?
What diode do you prefer?
Almost any standard diode should work. I tend to use 1N1004s, because it have them lying around. You should put it backward across the relay. This way, when the relay turns off, the positive voltage spike on gnd is shorted back to other sided of the relayy coil. Here is a schematic of this:
Michelangelclone (author)  E_MAN3 years ago
Ok, now I think I got it xD
You both mean a "flyback diode" to protect the relay coil-circuit (not the Arduino) from voltage spikes...
Yeah, I really should fix it.
Thanks for giving me food for thought :)
agis683 years ago
no need of any programm for arduino?
Michelangelclone (author)  agis683 years ago
Well,.... what?!
Of cause you need to programm your arduino^^
But there's no need for a special progamm or library to use your D2A-'Interface' with, use it just like a normal pushbutton.
Everyone who is in arduino should know how to use a pushbutton...