Trailing Edge Dimmer
A dimmer type that cuts the trailing end of each AC wave cycle. Smooth, quiet, and compatible with most LED bulbs — the recommended type for LED dimming.
Trailing edge dimmers are the gold standard for LED dimming. They work by cutting the back end of each AC power wave cycle — hence "trailing edge." This gentler approach produces smoother dimming, less audible buzz, and better compatibility with the sensitive electronics inside LED drivers.
The difference between trailing and leading edge is audible before it's visible. A leading edge dimmer on an LED load often produces an annoying buzz or hum from the bulb — the rapid voltage chopping at the front of the wave creates vibrations in the driver components. Trailing edge dimmers cut from the back, which the LED driver handles far more gracefully.
Trailing edge dimmers also support lower minimum loads than leading edge, which matters when you're dimming a single 9W LED bulb instead of a 60W incandescent. Some leading edge dimmers need 40-60W minimum load to function — well above what one LED draws. Most trailing edge dimmers work down to 5-10W, making them suitable for even a single LED bulb on a circuit.
Specifications
| Also called | Reverse phase, ELV dimmer |
| Best for | LED and electronic low-voltage loads |
| Noise | Very quiet |
Related Terms
- Leading Edge Dimmer
A dimmer type that cuts the leading (front) edge of each AC wave. Originally designed for incandescent and halogen — can cause buzzing and flicker with LEDs.
- TRIAC Dimmer
The most common phase-cut dimmer circuit, found in most residential dimmers. Works by chopping the AC waveform. Some TRIAC dimmers work with LEDs, many don't.
- Flicker
Rapid, repeated changes in light output. Can be visible (strobe effect) or invisible but still cause headaches. Usually caused by incompatible dimmers or poor LED drivers.
- Minimum Load
The lowest wattage a dimmer switch needs to function properly. Many older dimmers require 40-60W minimum — a single 9W LED bulb won't meet that threshold, causing flickering or failure to dim.