1 Pack 24 Volt Transformer, 40 VA AC Transformer Plug in with PTC Fuse Competible with All Versions of Ring Doorbell and Thermostat, Compatible with Nest, Ecobee, Sensi, Honeywell, 24V Adapter

I purchased the Hotop 24VAC 40VA plug in transformer to replace the 25.5VAC 25VA plug in power supply that came with my Rainbird ESP-Me irrigation controller. The original power supplies are notorious for breaking, and used ones in good condition go for $70 on EBay. The Hotop plug in transformer is a little over-rated for what the Rainbird system needed, but the Hotop was one of the very few 3 prong grounded 120VAC inputs with a 3 wire 24VAC grounded output that I was able to find to match the original Rainbird power supply. I used the 3 wire cord from the original supply and connected it to the 24VAC screw terminals on the back of the transformer case. The measured voltage output from the Hotop read 27VAC with 124VAC input from my house outlet. The original power supply (25.5VAC output) supplied 29VAC, so I'm not worried as the 27VAC is within the range of the 24VAC control valves in my system. Excellent product for an excellent price.

I installed a Nest Thermostat (the basic non-Learning one) in my home, but was unable to use the transformer on my zone controller - it was way too old and not outputting nearly enough power to keep the thermostat on. This solves the problem! If you have the same problem (2-wire heat only, no Common wire) here's how to power your thermostat. Doing it this way, you'll plug in the transformer near your furnace and won't have to have the wire or transformer visible from your living space. You will need:1. A transformer (this item)2. A Nest Power Connector3. Nest Thermostat already installed and firmware updated4. Pages 10-11 of the Nest Power Connector Pro Installation Guide - The "Pro" guide has the necessary info for installing with an external transformer, the basic version does not.5. Some 18/2 thermostat wire to connect the transformer to the Nest Power Connector.Good luck!

Product works and easy to install as advertised. One caution: do not connect it to a doorbell chime if the chime is powered by a 16-volt transformer.

The adapter works well, and I like the LED shows it has power. The only thing is it gets warm and this is power being used 24/7. (that's about 31 kWh per year or about $11 a year @ $0.38/kWh )

Used with isolation relay to power Ecobee Smart thermostat.

I purchased it for my ring doorbell. That way I don't have to change the battery in charge it up. I can just run it off of this device.

Needed a 24VAC transformer to power my new zone board for my AC unit. This transformers provides power to the zone board and full time power for two thermostats. It is great that it has a built in auto resetting fuse and plenty of power for multiple things at the same time. It does output slightly higher than 24V at just around 27V so make sure what you are using it for can operate at slightly higher voltages. In my case this is driving two zone damper motors, two thermostats and providing operational power to the zone board. Have had it in use now for a little over a month without any issues. I purchased the two pack to have a spare on hand. It is operating in my attic so will be susceptible to the heat of the summer and the zero degree weather of the winter. It does run warm to the touch when in use so be aware if you are using it openly in a living space. So only time will tell how it holds up to all the temperature swings and rigors of 24/7 usage.

Bought it for Ring doorbells but after 3 months, it stopped working and cannot provide enough voltage anymore.