HQRP Tri-Volt (8V 20VA, 16V 30VA or 24V 30VA) Transformer Compatible with Ring, Nest and Standard Doorbells Door Chime Power Supply Adapter Door-Bell 120v-to-8v-16v-24v Replacement, UL Listed
24VAC 40VA Plug in Transformer,Doorbell Transformer Compatible with All of Doorbell,Nest, Ecobee, Sensi and Honeywell Thermostat - - Amazon.com
24 Volt Transformer, C Wire Adapter for Nest Honeywell Ecobee and Sensi Thermostat, Doorbell Transformer Compatible with Wyze Video Doorbell - - Amazon.com
RepSupplements 40VA Transformer Primary 120V Volt 24V Secondary HVAC Furnace
PWS-2420 24VAC 20VA Class II Power Supply AC Adapter UL 24V Transformer Plug with terminals
Amazon.com: BASLER Electric BE242340RDD 40VA Class 2 Transformer, PRI:230V, SEC:24V : Electronics
STANCOR P-8575 Voltage Transformer 24V-CT 115/230V-AC: Amazon.com: Industrial & Scientific