Trailing Edge Dimmers Detailed Explanation for Home Lighting

Are you feeling uncomfortable about the glare of the led lights in your bedroom, study room, or office? To dim the brightness of the led, we will usually use a dimmer. However, not all adjustment tools adjust brightness equally.

Here, we will help you better understand trailing edge dimmers and how to differentiate trailing edge dimmers and leading-edge dimmers.

Why do you need to adjust the LED brightness?

Dimmer helps to adjust light intensity of LED light to meet everyone's needs
Dimmer helps to adjust light intensity of LED light to meet everyone’s needs

LED technology today has many outstanding developments and can be adjusted to arbitrary brightness. The light quality of LEDs is much better than incandescent and fluorescent lamps.

However, in the process of using it, sometimes you will be glared at by the light of the LEDs so we need an LED dimmer. The need to reduce the brightness of the lights may also arise if you have been on vacation or watching TV and you absolutely do not want to get out of bed.

LED dimmers allow adjusting the quality and light intensity of the led lights to meet everyone’s needs. They are used to ensure the correct voltage of the lamp.

At the same time, dimmer helps to stabilize the power supply and the life of the LED lights. The reason is that LED lights want to operate stably and have a long life, the power source is an extremely important factor.

However, you need to make sure that the LED and the regulator are compatible with each other. You need to be able to distinguish how to use it properly.

***Refer to more articles: Top 6 Best LED Filament Bulbs: Perfect Choice for Classic Style

3 ways to adjust LED brightness

3 ways to adjust LED brightness
3 ways to adjust LED brightness

#1. Method 1: Use the brightness control switch

  • This accessory is also known as Dimmer. Not all LEDs are suitable for use with a control switch. Therefore, customers need to carefully read the product information on the packaging announced by the manufacturer.
  • Dimmer works on the principle of adjusting resistor values. When changing the resistance values, the amperage will also change accordingly. Thus, the light intensity in the general model is also adjusted.
  • Dimmers fall into two main categories: digital tuning and internet-linked tuning.
  • Note: when installing a Dimmer for luminaires, the power of the control switch must be greater than the full capacity of the lighting system.

#2. Method 2: Use an LED dimmer circuit

  • The essence of this regulator circuit is to use a triac to change the light intensity of the LED bulb.
  • When using a triac regulator circuit, two cases occur. One is, the light is still on but the light mode is not adjusted or changed. Second, the light is still on, the light intensity has changed, but the change is uneven.
  • Use a MOC3021 circuit and a bridge circuit to detect zero points in the 220V AC circuit.
  • The installation of a triac regulator circuit is quite simple, but the efficiency of using this circuit is not appreciated. Therefore, it does not have much practical application, only suitable for expanding knowledge.

#3. Method 3: Adjust LED brightness with Arduino

An Arduino to adjust LED brightness
An Arduino to adjust LED brightness

Need to prepare the following components: Prepare an Arduino circuit, connection cable, a red light, update Arduino software.

There are 3 main steps:

  • Step 1: Connect the USB end to the computer via the connection cable.
  • Step 2: Plug the other end of the cable into the Arduino circuit.
  • Step 3: Access the pre-installed Arduino software, create the appropriate software to control the light intensity according to your wishes or needs.

Compared to the above two forms of tuning, using an Arduino is more complicated, requiring many skills related to programming and specialized knowledge.

Types of dimmers

When considering the dimming of a typical power supply, there are two main types of dimmer to look out for. These are called leading and trailing edges. Other types of dimmers including Dali and digital still exist – however they are often used in much more sophisticated lighting solutions than tend to be found in homes and offices.

Together, the leading and trailing edge dimmers are called phase-cut dimmer and they are named for the part of the AC wave they cut away to dim the light.

The leading edge dimmer switch cuts off the front edge of the half-cycle of each AC wave, while the back edge dimmer cuts off the second half of each half-cycle.

Dimmable LEDs are available in both front and back edge versions depending on the manufacturer, so it’s important to be sure the type of LED dimmer you’re looking at to make sure they’re correct to your specific application.

***Refer to more articles: Dimmable vs Non Dimmable LED Light: Which is better choice?

What are Trailing edge dimmers?

Trailing edge dimmers are dimmers that use switched-off currents. When the AC wave ends, before it crosses zero, this current turns off. This modifier is used with electronic drivers and avoids overcharging of the light source.

Differences between leading edge and trailing edge dimmers

Differences between leading-edge and trailing edge dimmers
Differences between leading-edge and trailing edge dimmers

To dim the LED’s brightness, we often use dimmers. The most popular modifiers these days are leading-edge dimmers and trailing edge dimmers. So which regulator do we use? Which regulator will suit your usage better?

# Leading-edge dimmers

This is a rather outdated lamp dimming tool. This tool is suitable for lighting systems that are more than 20 years old. This tool works with resistive or inductive loads. As a result, the electrical load can be reduced by shortening the alternating current (A/C) cycle at the leading edge of the input waveform.

To be able to distinguish the types of switches, you can rely on their capacity. For leading-edge dimmers, typically 100W – 600W is used. Their minimum power will be from 25W – 150W. However, leading-edge dimmers will not normally be used for LEDs, because the voltage of the LEDs is too low to meet the minimum voltage of leading-edge dimmers. Furthermore, current leading-edge dimmers have quite outdated technology, if your home is using this type then we recommend you to upgrade.

# Trailing edge dimmers

This is the most modern LED dimming switch available today. Of course, for the same reason, trailing edge dimmers are more expensive than leading-edge dimmers.

This dimming tool works with resistive or capacitive loads, helping to shorten A/C cycles. This tool can be used with a 240V load, with a minimum of 12-24V. So it is friendly with LEDs and effectively dims LED bulbs. In addition, this regulator also works with very gentle LEDs, keeping the LEDs long.

Therefore, trailing edge dimmers are the leading tool for us to dim the brightness of LEDs, with a very simple operation. However, before using you also need to consult an electrician or other professional.

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Things to keep in mind when using trailing edge dimmers

Things to keep in mind when using trailing edge dimmers
Things to keep in mind when using trailing edge dimmers

Not all LEDs are dimmable – make sure you check product specifications before purchasing.

If you have a dimmer installed but are unsure of the type of dimmer it uses, you should check with the dimmer manufacturer before considering possible LED bulbs. Incompatible combinations can cause LED bulbs to flicker and dimmer buzz

Be sure to check that the minimum and maximum load of the dimmer switch matches the number and combined wattage of the lamps and lamp fittings in the circuit.

Do your research to make sure that your lamp and dimmer are compatible with the same type of dimmer. If possible, it may help to compare the lamp manufacturer with your dimmer manufacturer. For example, we recommend using the BG dimmer switch with the BG Luceco dimmer

If matching your lamp manufacturer with the dimmer manufacturer is not appropriate or you would like more flexibility in case of future lamp manufacturer changes, you may consider the module dimmer Hamilton LEDIT-B100 or Click Scolmore MD9014 Dual Mode dimmer module. These modules allow you to easily choose between leading or trailing edge blur depending on your application.


Nowadays, the use of LED lights is more and more popular, leading to increasing demand for led dimmers. Many units were established to meet this need. Therefore, it is inevitable that many units work without reputation and provide poor quality products.

Before buying trailing edge dimmers, you should choose a reputable supplier to buy quality products. At the same time, before deciding to use, you need to consult with experts or electricians to choose a suitable installation place.