24VAC 40VA Plug in Transformer,Doorbell Transformer Compatible with All of Doorbell,Nest, Ecobee, Sensi and Honeywell Thermostat - - Amazon.com
24V 830mA Thermostat and Doorbell Transformer, Wall Transformer with PTC Fuse Compatible with Nest, Honeywell, Ecobee and Sensi Thermostat, Nest Hello and All of Doorbells - - Amazon.com
Amazon.com: Accessory USA 12VAC 5A 60VA AC AC Adapter for TDC Power Model No.: DA-60-12 DA-6012 Class 2 Transformer 12V 5000mA Power Supply Cord : Electronics
60VA-102/12V Solid State Transformer - - Amazon.com
Halogen Transformer ET60T Self - 2 (60 W) Operating voltage 10–60 VA Small Electronic Transformer : Amazon.de: DIY & Tools