WUYELIN 24VAC 40VA Plug-in Transformer for Doorbells & Thermostats – Nest, Ecobee, Sensi, Honeywell Compatible

Powerful, reliable 24VAC 40VA transformer for doorbells and thermostats

The WUYELIN 24VAC 40VA plug-in transformer is designed to deliver steady, adequate power to both your doorbell and smart thermostat. By providing a sturdy 24-volt supply with a generous 40 VA rating, it can reduce the need for frequent battery changes and help you avoid power-related interruptions.

The unit supports a standard 120 VAC input and delivers a clean 24-volt output. A no-load voltage around the mid-20s (approximately 26.6 V) is typical, and the secondary line is protected by an auto-resetting PTC fuse to help guard against minor faults while keeping power ready when you need it.

Key specifications and safety features

• Input voltage: 120 VAC, 60 Hz
• Output voltage: 24 V, 40 VA
• No-load output: ~26.6 V
• Auto-resetting PTC fuse on the secondary for safer operation
• LED green power indicator shows when the transformer is powered

Compatibility at a glance

• Compatible with popular thermostats: Nest, Ecobee, Sensi, and Honeywell
• Also suitable for doorbell systems and video doorbells such as Video Doorbell, Video Doorbell 2, Video Doorbell Pro, and Nest Skybell

Installation and cable management

The transformer outputs with screw terminals, allowing you to cut and route the connecting cable to fit your space. This makes wiring neat and visible cables easier to tidy for a cleaner install.

Testing and notes

• When testing with a multimeter, use an AC voltmeter to measure output voltage
• Measured no-load values around 26.6–28 V are normal and do not indicate a fault
• The brand names listed are for compatibility reference and do not imply endorsement

In short, this transformer is a practical upgrade for setups that require steady 24 V power to support both a doorbell and a thermostat. It focuses on reliability, simple installation, and clear status indicators to help you manage your smart home more smoothly.