Triac Series

Leading Edge vs Trailing Edge TRIAC Dimming

TRIAC dimming works by cutting portions of the AC waveform, commonly referred to as phase-cut dimming. There are two main types:

Leading Edge Dimming (Forward Phase)

• Cuts the beginning of the AC waveform

• Traditionally used with incandescent and halogen lighting

• More affordable but may cause noise or flicker with some LED loads

Trailing Edge Dimming (Reverse Phase)

• Cuts the end of the AC waveform

• More suitable for modern LED lighting and electronic drivers

• Provides smoother dimming performance with reduced flicker and noise

In modern LED applications, trailing edge dimming is generally preferred for better compatibility and stability.

Universal (Leading & Trailing Edge Compatible) Dimmers

In addition to standard leading edge and trailing edge dimmers, many modern TRIAC dimmers are designed to support both dimming modes. These are often referred to as: Universal TRIAC dimmers, Leading & trailing edge compatible dimmers, Auto-detect dimmers.

These Triac controllers can automatically detect the connected load and adjust the dimming method accordingly, ensuring better compatibility with different types of lighting such as LED drivers, dimmable bulbs, and power supplies.

For a deeper understanding of how TRIAC dimmers work, including waveform control, compatibility considerations, and real-world applications, check out our detailed Triac Dimming Guide.

How Does TRIAC Control LED Strip Lights?

TRIAC dimming can be applied to LED strip lighting in several ways, depending on the system design:

1. Direct Control of High-Voltage LED Strip Lights

A TRIAC dimmer or controller is connected directly to high-voltage LED strip lights (AC LED strips), allowing direct brightness adjustment.

2. TRIAC Control with AC Power Supply (AC → DC)

A TRIAC controller or module controls the input of a standard AC-to-DC power supply, which then powers low-voltage LED strips.

3. TRIAC Dimmer + TRIAC DC Controller

A wall TRIAC dimmer is connected to a TRIAC-compatible DC controller, which regulates the output to LED strip lights powered by a separate DC power supply.

4. TRIAC Dimmer + TRIAC LED Driver

A TRIAC dimmer is paired with a TRIAC dimmable LED driver, which directly controls the brightness of connected LED strip lights or fixtures.

Each method offers different levels of compatibility, control precision, and installation flexibility, making TRIAC a versatile option for both retrofit and new lighting projects.