speaker relay

Are you switching the positive or negative with the door bell switch?

I was thinking of a setup like this:

Pushing the button will pull the relay in

The relay will stay pulled in for as long as the button is pushed

Releasing the button will start the adjustable timer (0-30s roughly)

Does that sound about right?

AC Voltage works different than DC Voltage.

We are dealing with 24vac.

No Positive or Negitive.

You could get a time delay relay relay from grainger with a 24v control voltage.

http://www.grainger.com/Grainger/wwg/viewCatalogPDF.shtml?browserCompatable=true&adobeCompatable=true&toolbar=false&CatPage=410

Yeah I guess a transformer with no rectifier kind of gives that away, I'm not sure what I was thinking.  Thats brings up a different question, the OP asked for a 24VDC relay in the first post, so what kind of relay are we using?

My circuit should work with AC voltage, as long as its below 30v.  I'll just have to software filter the AC signal to a DC signal.  Outputing a signal to the relay may be a bit more tricky, but shouldn't be an issue,  I'll have to go out in the garage and see if  I can dig up a transformer and do some testing.

All the componenets showed up yesterday, but the circuit boards won't be here till next Wednesday.   

hotwaterwizard and KPierson-- You guy's are great and it looks like this topic has taken on a life of its own.  Thanks for all the great information.

Just to clarify the issue of voltage (AC vs DC), I am using 24Vdc.  THe chiming unit uses -24Vdc and I ended up using 4PDT relays to break the speaker cirucits just after it leaves the volume control (as opposed to just after it leaves the hub as depicted in my earlier drawings).  THis alows everything to work in a normal music environment and the relay only takes over when the doorbell button is depressed.  As soon as it is released the relay closes and music starts back up.  Installing the relay this way takes the volume control out of play when the doorbell rings thus allowing the chime to go directly to the speaker terminal without having to worry about whether that particular volume control is turned up.  The only remaining thing I have to figure out is how to keep the relay activated long enough for the preprogrammed chime to play (roughly 3 seconds) and then where to insert this timer.

I have looking at the  DEI-528T but have never used one of these and don't know if it will sove my problem.  THe current relays are already "wired in" and all of the cables are dressed....so I really hope I don't have to install a new set of relays.  I would prefer to insert a timer in the button circuit as it is much easier than having to undress and rewire the entire panel.

Thanks again fo all your assistance.

Chris,

The board should be here today!  Where are you getting your 24VDC?  Do you have a power supply providing it?  We will need a 7-30vdc power source to power the microcontroller.  The module will hook up to power, ground, door bell switch signal (which I will need to  know if its a (+) or (-) signal, and the output will hook to the relay coil.  Should be a simple install, no need to rewire the relay contacts at all.

Thanks,

Hi Kevin,

The chime unit is using -24Vdc.  I am suppling this power via a 24Vdc 500ma transformer that simply plugs into the wall.  It has screw terminals on the power supply so I hard wired it directly to the Valcom Chimer.  I have access to either voltage (+ or -).  I also have an additional power supply so if need be, I  can use it to power your circuit.  Let me know what questions I can answer......Thanks  Chris 

The existing transformer should work fine, the module will only pull roughly 25mA. 

How is the coil of the relay hooked up now?  Are you switching the (-) feed to the coil, or the (+)?  With my module, we will have a switched (-) out capable of 100mA.  So, technically, we would need the (-) side of the coil switched.  This way, you could remove the (-) feed to the relay, input it in to my board, and then connect the output of my board to the (-) side of the coil.  How does that sound?

Oh, and I have one of the boards in my hand right now!  All I have to do is write about 100 lines of code or so, and we'll be in business!

Sounds good.  I believe that I am running -24 to the coil of the relay wheneve the button is pressed.  As soon as the button is released....the coil de-energizes and go to N.O.

Chris

PS I am about to go out for the night (wife's xmas party) so I won't be able to respond to questions until tomorrow am.

Got the module built and programmed last night.  The module works just as I had described above.

4 wires:

When you apply a (-) input to the orange wire the (-) output is turned on.  The (-) output stays on until the input is removed.  Once the input is removed the (-) output will stay on for a period of time proportial to how far the know is adjusted.  The delayed output is adjustable from 0-30 seconds in 1/1024 increments (10bit resolution).

The first pic is of the circuit itself.  You can see the adjustment knob in the top right corner of the board.  The IC chip operates at 1mhz, and draws roughly 8mA at idle.  When the output is on the current draw will be roughly equivalent to the current draw of the relay coil itself + 10mA. 

The bottom picture is the module in its final state.  Unfortunately for you, this was the first enclosure that we drilled a hole in, and its kinda sloppy, but I don't think you'll mind  :)

Please send me your shipping info (including full name) via PM and I'll drop in in the mail tomorrow or Tuesday.

Thanks!