My 1970 built house has a 16v, 10VA doorbell transformer. I measured 19.5v at the button. It has a conventional chime. I know the specs say => 10VA but there’s a long thread about it not working with a 10VA transformer. Just wondering if anyone has gotten the chime to work with a 10VA transformer. Not sure I want the hassle of replacing mine just to get the chime. I could just get the v1 doorbell instead.
Welcome to the Wyze User Community Forum @lmacmil! 
I’m confused. If it is a 16v transformer, how are you getting 19.5v if it is operating normally? Per the specs, you only get 16v at .625A
If your transformer holds true to the Amps per spec, at 19.5V you will actually be at 12.19VA. if the VA is true at 10, then you only get .513A at 19.5V
But, that still doesn’t mean it will have enough power to run all three.
I’m just reading what’s stamped on the transformer and what my voltmeter read at the doorbell button. I may have another issue because this morning with the outside temp at 20F, my doorbell would not ring. I have had this issue in the past. I don’t know if it’s the button or something else. I will measure the voltage again at the button to see what it is.
Update: the voltage at the button is less than 1v. At the transformer which is in the basement at 68F, the voltage is about 2.2v. So something in the wiring between the transformer and the button is temperature sensitive and causing the voltage to drop off to almost nothing. I have no idea what that would be. At least one other neighbor has told me their doorbell doesn’t work in the winter either!
A 1.2 V drop from the Transformer to the Bell is not that much and would be expected over a long run low voltage wire when the transformer volts are that low.
The issue is with the Transformer output. First you had a 16V Transformer putting out 19.5V, now you have a 16V transformer performing at 2.2v. That is an issue. It is all over the map. Like us old people, old transformers don’t like to work in the cold.
Time to upgrade to a new 24V 20VA+ transformer.
Thanks for the reply. I figured I would need a new one to work with a video doorbell. What I can’t figure out is why the transformer, which is in my room temperature basement, is affected by the outside temperature.
I use and recommend this transformer. It has been in operation since November 2019
Elk TRG2440 24VAC, 40 VA AC Transformer with PTC Fuse
Thanks but I need something that mounts on a junction box and has wires to connect to the 120v wiring. There’s no outlet close by.
Amazon or your local Box hardware store. Just do a search for 24V 40VA Doorbell Transformer. There are oodles of possibilities.