Relay for 16vac

Hi, I need a NO relay that operates on 16vac. It will be used in a door bell circuit so the amount of time the relay is energized is less than a second.

My question is if I can't find a relay with a coil designed to operate on 16vac, am I better getting one that will operate on 24vac, (will they generally energize at 16vac), or should I get one designed for 12vac since the coil will only be energized during the duration of the door bell push?

I appreciate anyone's thoughts.

Thanks,

Chuck

ChuckC said:

will they generally energize at 16vac

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Generally will bit you next year when the relay is old and less likely to work.
One option is to add a resistor in series with the 12V relay. We might have to experiment so to find a resistor that will eat up 4 volts.

I would use a 12vac version, or actually measure the 16vac as many of these bell transformers output a little higher.
Relays are not that critical devices, especially when used momentarily, an alternative is to use a bridge, electrolytic Cap and a 24vdc DC relay, I have found the hysterisis on the DC versions are Much wider.
Max.

ChuckC said:

My question is if I can't find a relay with a coil designed to operate on 16vac

Click to expand...

You may be able to use this, which is designed to operate from 10-30 VAC (see the data sheet for the connection leads).


Does your existing wiring correspond to one of these?
**broken link removed**

Are you using the signal out from a 16VAC transformer?

Thank you. It looks like the RIB RIBU1C-RD might do the trick. As far as the doorbell wiring diagrams, this is an "unconventional" connection; I'm integrating a Nest Hello video/WiFi doorbell into a Nutone intercom system.

You could use a 12v dc relay and something like a wo5 bridge rectifier module, the rectifier converting the ac to dc, and loosing 1.2v in the process, the extra bit of voltage could be dropped by a resistor, and its unlikely someone will be holding the bell push in for an hour, unless you havent paid your bills.

ChuckC said:

Thank you. It looks like the RIB RIBU1C-RD might do the trick. As far as the doorbell wiring diagrams, this is an "unconventional" connection; I'm integrating a Nest Hello video/WiFi doorbell into a Nutone intercom system.

Click to expand...

Hi Chuck. I'm trying to do the exact same thing. I'm trying to find a relay that will tie into my Nest Hello that will activate the door chime in my M&S intercom system. Bought an Alpha Communications PK407A - 16VAC relay. I mocked it up and tested it and it seemed like it would do the job. I was getting good continuity immediately after pushing the button on the Nest Hello, but my the time I went to permanently install it, the relay was no longer working. The transformer is actually putting out almost 18vac, so I'm not sure if it was too much for that relay.

Anyhow, did the RIBU1C-RD work out for you?

If you rectify and filter your 16 VAC (rectifier and capacitor) you'll have nearly 22 volts DC to operate the relay. Close enough to 24 unless you're using some massive industrial contactor.

Thanks for your reply. Here is what I'm trying to do....
I have a Nest Hello that is connected to a 16vac door bell transformer. My house doesn't have a traditional door bell, it has a whole house intercom system with the door bell/speaker at the front door. When you press the doorbell button at the front door, it completes a circuit inside the unit at the front door and activates the chime in the intercom system. The Nest Hello is designed to be attached to a traditional door bell and thus outputs a momentary 16vac current to activate the bell. This 16vac is not enough to trigger the chime in the 28v intercom system. So I was trying to use a 16vac relay so that when the relay is activated using the 16vac signal from the Nest, it would be wired so that it would complete the circuit at the intercom doorbell at my front door, ultimately activating the intercom chime when the Nest button is pushed.

I think that's the same thing Chuck was trying to accomplish. I bought the relay I mentioned in my previous post which is rated for 12-16vac. The 16vac transformer I bought us actually putting out 18vac, so I wonder if it was too strong for the relay I bought because it stopped working.

Any thoughts or ideas are appreciated.

Thanks!

The 16vac transformer I bought us actually putting out 18vac, so I wonder if it was too strong for the relay

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If you're talking about an actual transformer, then a higher than rated open voltage is pretty common.

On t'other hand - I've seen many small general purpose "24V" mechanical relays work quite reliably on as little as 5V. They tend to be pretty forgiving if they're not pulling a ton of armature.

Do you have any examples or links to share on something that might work? It looks like the RIBU1C-RD mentioned above could work.

Thanks!

Sorry I don't off hand. I could check Friday, but no idea as to how generic - or house - the numbers may be or vary. When I come across salvage bits I tend to play a bit loose and wild for "go/no go" initial checks (does it "Click"?). However, I can't recall off hand a small PCB mounted 24 relay that didn't pull in with 12. Even a handful of "plug ins" that came from industrial control salvage. I'd hazard a guess that the smaller physically the relay package is - the more likely it will actuate under rated voltage, where as five pounds of 24V contactor switching 600V three phase would likely be a bit more fussy.