Pulse Width Modulation

Pulse Width Modulation


Our LED circuits at Environmental Lights are designed to operate at a constant voltage; Typically 5, 12 or 24 volts DC. For this reason, to dim our lights, we cannot simply reduce the voltage or the current flowing through to them. We use a Pulse Width Modulation (PWM) to dim our products. PWM is a very common method of dimming LED lights that works by very rapidly turning them on and off (pulsing) for periods that visually appear as a steady dimmed light. We adjust the brightness level by adjusting the percentage of the time the lights are on (100%) to the time they are off (0%).

What is duty cycle? Hertz?


How is PWM measured? Where can I found output PWM frequency information?

PWM frequency is measured using an oscilloscope to view the period length. Each controller is tested in our lab for accurate results. This information is posted under the “Specifications” heading or can be found in the manual under the, “Documentation” heading for the particular controller on our website.

What is a good PWM?


If that’s true, then why does Environmental Lights sell controllers with such high PWM frequencies?


Video cameras, especially those used in professional studios, can pick up on flicker at much higher frequencies than normal cameras. For this reason, Environmental Lights has developed the Studio Line. All controllers in this line have a PWM frequency between 5,000 and 30,000 hertz, or they use a scrambled PWM (see Scrambled Pulse Width Modulation) of 2,000 hertz.

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