LED dimmers do not vary the voltage, they vary the period of time (ie part of mains waveform only) during which power is applied to the LED.

I neither have buzzing nor flicker with typical light switch dimmers.

rather than ordering from epay where there is little control over quality I’d suggest find your nearest trade dealer eg City Electrical, TLC (they have a useful paper catalogue), Rexel etc and buy matching lamps + dimmers – they will usually give trade discount if asked + have advantage stuff can be returned if faulty

To back up John’s point – most dimmers intended for heavy loads have a minimum load that far exceeds a puny LED lamp.

Edited By Frances IoM on 20/08/2019 16:29:31

Edited By Frances IoM on 20/08/2019 16:30:04

That might be roughly true of a silicon diode but it ain't so for an LED, as they don't use silicon as the semiconductor. As a rough guide forward voltage drops of LEDs are as follows:

Red ~2V

Yellow ~2V

Green ~2.1V

Blue ~3.3V

White ~3.6V

Like silicon diodes the forward voltage drop of a given LED is dependent upon the exact type, manufacturer, forward current and probably the phase of the moon.

Andrew

Nick is quite correct – And therein lies the problem. most of those driver electronics are basic buck switchmode types, with constant current control to the LED in the lamp. So, varying the input voltage ( the mains) has , over a very broad range, no effect on the LED's brightness, as the controller simply adapts to ensure the LED receives a constant current. So, many of the basic LED lamps do NOT dim , or do not dim well. You may notice the splurb on some lamp's packaging indicating that the lamp is dimmable – That is there for a reason…

Some LED drivers ( the electronics inside the lamp) may dim, sort of, as the input voltage is varied down to a level. The electronics will increase the pulse width in its control loop, trying to keep the LED happy with enough current, until the PWM controller runs out of input voltage and the control loop is simply fully on – the PWM pulse width is then at max, and as you drop the input voltage further, the voltage of the pulse drops as well, and so the lamp dims.

The effect is that at full volume, the lamp is brightest, with NO change in brightness as you dim down, and then suddenly , at some point, it starts dimming. Dimming further most often results in the lamp dimming and then just cutting of, before you reach minimum setting on the dimmer, where the PWM controller itself runs out of functional voltage. During this dimming process, some lamps not intended for dimming even succeed in popping..

Just try make sure the lamps you use indicate they will work with conventional wall dimmers…

Joe

And also, as has been mentioned, Hi powered dimmers don't really work well on with low power lamps, esp the more common Triac dimmers – they start flickering at the low settings and drive you mad. There are more specialized wall mount dimmers that work with low wattage lamps. I have fitted dimmers that specify down to a 10watt load, using them on a 25 watt reading lamp above the bed headboard..

Edited By Joseph Noci 1 on 21/08/2019 07:40:00