video doorbell with mechanical chime relay needed

[bkenobi]

High level question:
Does anyone know of/have a link to a 24VAC relay that will be close to silent and be as compact as possible?


Background:
I have a mechanical 8-note chime in my house and have been using a Ring camera for years.  It's fine at best but a couple years ago they changed so now it requires a subscription to do anything useful.  I had no issue with extra features being offered at an elevated price, but once Amazon took over, they made it basically a 2-way camera with very slow ring notifications.  In any case, I'm going to replace with something else.

The current camera offerings do not work with 4- or 8-note door chimes because the motor that runs for up to 16 seconds uses power too long and kills the camera.  Most of these cameras have either nothing, a small capacitor, or a small battery.  If they have a real battery, they remove other features I want.  So, I'm left having to make it work without manufacturer support (what else is new!).

The solution is to add a relay to accept the trigger from the chime and simulate a button push and then provide power to the doorbell camera constantly from the transformer.  This is fairly simple in theory, but I'm not having luck finding a suitable relay.  The requirements are that it needs to work with 16-24VAC, must be small so it will fit inside the chime box, and ideally be near silent.  The AC relays I have found/used in the past are rated for ~110VAC.  If I can't find one for lower AC voltage, I suppose I could use a full bridge rectifier to convert to DC but that makes things a little bigger and space is at a premium.

[Brian H]

Have you tried looking on EBay?
There are some there.
24VAC USA sellers and Chinese so you have to read carefully.
I did see an IDEC but it my not be small as you would want.
https://us.idec.com/idec-us/en/USD/Relays-%26-Timers/Relays/RH-Power-Relay/p/RH1B-UAC24V

[Brian H]

Just a thought.
Have you verified it is 24VAC?
All the bell setups I have seen or have used are around 16VAC to maybe 18VAC

Search showed the 16VAC to 24VAC you indicated. If your setup has a 24VAC transformer. Then it should be fine. If it is a 16VAC doorbell transformer you my have to change it also.

[bkenobi]

My transformer is a Nutone 24VAC 10VA unit.  I suspect I will have to change it because most cameras recommend 30-40VA.  I ordered one from Amazon that looked like a good fit but it's outputting 27VAC and everything is getting super hot.  Many of the cameras are rated 16-24VAC and some down to 12VAC.  If everything above that is wasted in heat, that would explain why it got so hot.  I'm probably going to try again for the transformer but will test my existing one since it's been flawless for 40 years.

I looked on Amazon and ebay and found some that might work but wasn't having luck with anything small and no way to know how loud they are.  The alternative is to use a rectifier and a small DC relay.  That would be pretty small, I'd just have to figure out how to mount them together without it being too janky.  Maybe use the 3D printer to create an enclosure if I feel really outgoing!

[bkenobi]

I think any AC relay would work so long as it's rated for higher voltage than I'm using, right?  I have a couple 110/220VAC relays in my misc box so I could test.  If that's the case, then a simple Omron G5LE-14 would work.  And that is available on a little board Adafruit sells (https://www.adafruit.com/product/3191) If I felt the need to do that.  I was thinking that for AC I would need to have a minimum voltage for it to work and most only list the high end.  Seems like both min and max should be listed.

[bkenobi]

I called Digikey and they helped me with the filters on their site.  I was able to get the 35,000 relays down to a list of 19 that should work.  The issue is that there is a minimum coil voltage rating that I wasn't seeing (I knew it must be there somewhere).  Most of the 110/250VAC relays have a minimum coil rating on the order of 36VDC which would not work.  I think this one should work though.

https://www.digikey.com/en/products/detail/cit-relay-and-switch/J115F21A24VACS/14001911?s=N4IgTCBcDaIFYEYEFYBmYEEMwBYBumAxgM4gC6AvkA

[Brian H]

That may work.
As long as you have room and the normal coil current of 200mA is OK.
I have also seen some vendors not giving things like must pull in and must drop out ratings.

[bkenobi]

That was my initial problem.  I was trying to locate the minimum actuation and release voltage (must pull, must drop) but places like Amazon don't list that.  They include all AC relays with searches for 24VAC which is annoying.  If it's a 277VAC relay and it actuates at a minimum of 20% (55VAC), then no it will not work at 24VAC but they are sold as furnace relays.  Well they are good for a furnace internally since it runs at 220VAC but it is not good for the thermostat side for which they try to sell them.

Anyway, just have to place an order on one that looks small enough.