Hey guys,
Just joined these forums and have what I hope to be an easy question. Basically I want to tie into my doorbell switch to trigger an on/off event. I have a USB joystick I dismantled and have code working to monitor the joystick to see if one of the buttons is pushed, from what I can tell it's grounding the button to create the circuit on the joystick. I also have a pair of leads coming from the doorbell switch separate from what goes to/from the 16v ac transformer (standard for wired doorbells). Trouble is, I'm pretty sure because I'm connecting to the same switch as the doorbell transformer I've got 16v AC running all the time through one of my switch leads and momentarily through the other side when the switch is pressed, and that doesn't help me trying to trip this joystick switch. I was thinking a relay of some kind would work ok but hoped there would be a simpler/more elegant solution (though I can't seem to think of one). Any idea how to remove the 16v ac from the line but still keep the functionality of the switch intact?
Tom

 

Tom,

I think the easy way is to use a relay.

Ante :roll:

 

Any suggestions on a relay that operates at 16V AC and hopefully won't interfere with the doorbell?
Tom

 

Tom,

Who is your supplier, and what can they offer in relays?
Maybe there is a 12VAC relay with high resistance coil and you can add a series resistor.

Ante :roll:

 

I don't have a supplier... I am not sure about the 12v AC with resistor, won't that drag down the line so much that the normal doorbell won't get enough power?
Tom

 

Just a side note about doorbell transformers... most are what is called "class 2", meaning that they have a fuseable link incorporated into the windings that will open if the transformer is overloaded or shorted. Keep that in mind, since if you blow the "fuse" you get to buy a new tranformer, its not a serviceable item. It doesnt take long to blow either, a momentary oops shorting the wires together can do it.

 

Tom,

Just to straiten a few things out: A relay does not draw that much current and adding a resistor makes it draw even less. The thermal fuse in this type of transformer usually blow at 120C and this will take at least a minute of short before this occur. This thermal fuse is in series with the primary winding of the transformer and there is no way it will blow by “a momentary oops shorting”. If you feel insecure just add a fuse before experimenting.

Ante :roll: