40VA Control Transformer, Primary 120/208/240 V AC 50/60Hz Secondary 24V AC, Replacement for Jard 4031F Packard 42440 Gemline GT446 Robertshaw 620-206 HVAC Furnace Multi Tap - Amazon.com
Goodman 0130M00138S 240V to 24V Transformer - Amazon.com
HQRP 120V-240V to 24V 40VA Transformer Compatible with Nest, Ecobee, Sensi, Honeywell Thermostat, Nest Doorbell and All Versions of Doorbell Power Supply Adapter Door-Bell 120v-240v-to-24v, UL - Walmart.com
Lennox Parts 13H28 208-240V/24V 70VA Transformer: Amazon.com: Industrial & Scientific
Basler Transformer 110v to 24v – 20va – Airstream Trailer Parts
Source 12v dc transformator 24v to 220v step up transformer on m.alibaba.com