Prowinch Control Transformer 220/380/440-24V 50 VA All Series PWR 2 ton and up: Amazon.com: Industrial & Scientific
Amazon.com: Dean 8070800 TRANSFORMER 120 50/60-24V 50VA (8070800) : Electronics
24VAC 50VA Wall Transformer with PTC Fuse Compatible with All Versions of Doorbell,Nest, Ecobee, Sensi and Honeywell Thermostat,Water Solftener,Screw Terminal Output - - Amazon.com