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

Nice transformer

You'll find many doorbell/thermostat transformers on Amazon... many are underpowered. This one is not. It is hefty, and appears well-built. It can handle multiple smart thermostats (to provide the C-wire power). I recommend it, and will use it for all future C-wire/thermostat installs.

Excellent Product.

The control board of my home security system went dead the other day. I started dreading the idea of unhooking all of the zone inputs, and then thought that I should just do some basic troubleshooting. I tried to take a multimeter reading off of the huge block transformer, and voila... nothing. First, I didn't really think there was anything to fail on a transformer (it being just windings). Second, in looking for a replacement, I was struck by the fact that there don't seem to be any switching power supplies as drop-in replacements. Weird... especially since we're only talking about under 2A. At that point, it just became a matter of WHICH transformer. I settled on the Hotop 24VAC, 40 VA AC Transformer Plug in with PTC Fuse, for no reason in particular.The transformer has screw terminals, but no capture plate. It's not a big deal, you'll just want to wrap the leads around the screw a little. The transformer is a bit of a chunk, so there's a securing flange at the top of the unit. If you have a long enough screw, it will secure the block using the screw hole in old-style outlets. It would have been nice if they included an appropriate screw, but they didn't. You're out of luck if you use Decora-style outlets. In operation, you get what you get... the circuit diagram is on the product page. You have two fuses, windings, and an LED. It works. Recommended

Used with isolation relay to power Ecobee Smart thermostat.

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!

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.

It comes without wiring info, had to rely on photos on AMZ page.I had a new Ring, so I temporarily wired it with a short piece of new wire just to test everything.First thing I noticed is when I bent a “J” onto the wires to connect , the terminal screws are so close to the indent its all but impossible to get the wire around the screws.Plugged in and pilot light on so all good, except Ring said it didn’t have powerThe thing is very heavy ( which means it probably gets warmer after awhile ) yet the housing has no ventilation. Doesn’t seem like a long term solution.Lastly, the cover came half off when I unplugged it - gently . Didn’t bother wasting more time getting multimeter to test output. Returned it.