I would like to hook up an IOLinc to my doorbell to trigger a whole-house audio alert. Here's where we are:

Doorbell is a NuTone M516 with a front and a rear doorbell hooked up. I have found the doorbell wires. They are normally closed to supply a nightlight for the button. Measured voltage across them is 6.2v AC. When pressed, the contact opens and the voltage drops to 0.5 (not zero) or so momentarily and then jumps back to 10 v, falling again to 6v.

The IOLInc's S and GND are connected across the two doorbell wires. The IOLinc is set to send an "On" and log its state. The trigger (which never fires unless the IOLInc is disconnected) has been set up alternately to respond to an "On" or to detect any change in status, but no signal comes.

Suspecting a bad IOLInc I swapped another in. Neither will sense this level of voltage drop, although as noted when disconnected from the doorbell wires so there is no voltage whatsoever, they sense the drop from 6v to zero, respond appropriately and the trigger fires.

Thoughts? Seems like the IOLInc needs a zero voltage across the Sense/Gnd terminals. It's not getting that, and I don't know why there seems to be this leak voltage. Any way to get it to respond to a significant voltage drop?

Do the IOLincs do AC imputs? (not sure don't have one)
But remeber the AC signal hits zero volts 60 times a second. (swings above and blow zero.)

If they don't do AC, possibly a simple diode (to rectify) and a pull down resistor can solve the prob.

(I'm a bit 'off' right now to think it all the way through)

thanks, Anode. I may try that but would need a recommendation for the diode and resistor.

To clarify the post above, the only way I can measure a voltage change out of this doorbell and still have it work (it also broadcasts a chime through some intercom stations so is important to keep it intact) is to tie the IOLinc in parallel with the push button legs. I tried setting it in series, running one of the legs through the IOLinc, but there is not enough current -- or maybe the IOLinc just doesn't do AC as Anode says -- to pass thru the sense/ground loop and go back out to power the bell.

You asked on another thread what I did to interface small AC signals to an Insteon device. You can find these parts at any Radio Shack: 2 10K resistors, a 10 microfarad capacitor, a diode such as P/N 1N4007 (nearly any kind will work) and a terminal strip to mount and connect the parts.

Your doorbell circuit uses 6.2 volts AC, which may generate up to 9 volts when converted to DC. I'm using the two resistors to cut that voltage in half to avoid damaging the I/O Linc, which should not have more than 5 volts applied to its input (I hope it has not already been damaged by applying the AC directly to it). Wire it according to the following diagram, and let me know if you have more questions. I'm not guaranteeing that this will work is your case, but it was reliable in my system.


It looks to me that the input to the I/O Linc is not opto-isolated, so I'm a little uncomfortable connecting the doorbell wiring directly to it. (I used an EZIO device with isolated inputs.) Does anyone else have an opinion on that?

Otis, thank you very much for the detailed reply. Testing with a 1.5v AA battery, both IO Lincs are still working and Indigo is recording their state correctly.

I bought the parts you recommended - had to get a 22 microF cap as that was all that RS had - assembled, and measured a steady +2.88v DC. However, there was a measurable AC voltage of about 0.15 vAC. Don't know if that was significant, but the IOLinc is still not registering a state change. I added a second diode to rectify the other leg, but that appeared to make matters worse, with the IOLInc Sense LED barely glowing.

One other consideration might be an EZIOxx. I understand they can respond to voltage drops, not absolute ON/OFF conditions. Is that right?

Any further thoughts or suggestions?

Thanks again!

The first time I scanned through the I/O Linc manual, I missed the fact that it is designed to connect directly to a set of contacts, rather than having an external voltage applied to it. Sorry to start you off in the wrong direction. The circuit I showed should work with a device such as the EZIO6I. It's more complicated with the I/O Linc. You could probably fool the I/O Linc into working with this circuit, with some experimentation. If you want to continue with the I/O Linc, I'd suggest first finding out how low a resistor value placed across the S and GND pins of the I/O Linc will cause it to think it sees a closed contact. Then you could leave that resistor in place, and replace the resistor connected to the doorbell wires with one of the same or somewhat lower value. If it turns out that these new resistance values are high enough so that they don't affect the doorbell operation, then the circuit might work.

You'd need to make sure than when the doorbell is pressed, the voltage on the I/O Linc pins is low enough (probably one volt or less), and when the doorbell is released, the voltage is high enough (probably greater than 3 or 4 volts).

If you have more questions, let me know the AC and DC voltages that you see on the I/O linc inputs with the doorbell both pressed and unpressed.

This is a pretty kludgey way to get it working, but it's probably worth a try before buying a module like the EXIO6I. By the way, the EZIO6I can be a hassle to get working unless you use resistors to pull the analog inputs up to 5 VDC (which is not supplied by the module). A promising future choice might be the DLP-IO8, whenever some gets around to writing a plugin module for it (see www.perceptiveautomation.com/userforum/ ... 085#p42085)

If you could find a relay that would open and close as the doorbell is pressed, then you could just wire the relay contacts directly to the I/O Linc's input. That's the simplest solution, but you'd have to find a relay with a 6 VAC coil that would draw only a small amount of current.

Expensive, but Smarthome also sells this doorbell detector as part of an I/O-Linc Kit.

Also, look at Sean's post on this thread. If you rewire the doorbell button to the SNS and GND pins and then use the relay in the I/O-Linc to control the actual bell, then you don't need any more complex circuit.

Thanks for the followup. I think I'll order the Elk unit as it looks like it will get the job done. I had seen Sean's thread response prior to my initial post, but want to keep the Indigo system separate from the doorbell.

The hobby board was fun too - been a while - and I appreciated the effort and good advice. Will post back how it all works.

+1 on the Elk detectors; I've been using them for a while now and they work great.

Sure wish it had worked for me. I received the unit and read the instructions. Since it requires a 900 mA draw to execute, it needs to be hooked up to a real doorbell transformer that, when closed, delivers 24v AC and good current. As I have worked with this silly intercom/doorbell I've finally realized that it is really a primitive whole house audio system. It doesn't fire a doorbell, it sends a chime tone through the intercom speakers.

I called NuTone tech support. AFAIK there is no way to get 24vAC, DC or anything else out of the system to close a contact. Also there are no drop in replacement units. While I could easily just hook up the IOLInk to the doorbell button in place of the intercom, I don't want to lose the whole house doorbell as currently done by the intercom as my "real" whole house audio system is dependent on Serial Bridge, which, while quite reliable, is a bit shy of 100%.

My latest attempt is to get a bridge rectifier and put it in parallel with one of the legs of the doorbell to detect the voltage change when the button is pressed. So far it seems to kill the doorbell circuit by rectifying all the AC on that leg, but I'll try again.

very frustrating for something that should be so simple. Any other ideas would be welcome.

Thinking WAY outside the box, but a IR LED and IR receiver based solution? (basically a kludge of an opto-isolator, but Radio Shack obtainable parts)

Interesting. Can you suggest any parts? How about another illuminated doorbell in line with the current doorbell, and when it went dark (main doorbell pressed) it would trigger a photocell?

hamw wrote:Interesting. Can you suggest any parts? How about another illuminated doorbell in line with the current doorbell, and when it went dark (main doorbell pressed) it would trigger a photocell?

gimme a bit of time.

Success at last! Anode was on the right track to sense what **could** be sensed....

I recalled reading this thread some time ago: viewtopic.php?f=5&t=2062 re sensing the dryer. At the bottom of the first page Ricks suggests the SmartHome Audio/Video probe: http://www.smarthome.com/8016/Video-Pro ... obe/p.aspx

Since the intercom transmits the chime through speakers, I ordered one of the probes, hooked it to an I/O Linc, and lo and behold it worked! I think these probes might be quite useful for a number of applications. Thanks for all the suggestions on the thread; it was fun if a little frustrating!

Hi Guys or Matt,

I have a wireless doorbell button that sends a signal to a wireless receiver that is plugged into the wall (120V)
Is there a way to have something send a signal to Indigo when this doorbell goes off? It is a sealed receiver, so I think it would have to be something that senses the sound? (it would have to just attach to the outside of the receiver chime)
It is a "Ding Dong" type of sound, not a buzzer.
I saw on this post the Elk-930 from smarthome, but that requires wires to be run to it from the chime itself, which like I said can't be done. I need something that can just attach to the outside of the chime, that senses the chime sound.
I had originally thought I could run 2 wires from the actual doorbell button to a door/window switch, and have that send the signal to Indigo, but the doorbell button doesn't have any inputs to screw the wires to. It's a basic Lowe's/Home Depot wireless doorbell kit.
I know this would be extremely easy if the doorbell button had contacts that wires could be connected to.