Excellent article on Dimmers for LED Bulbs and why they do not always work properly

I was hoping they were going to pull this article out of the magazine - and today they did.
http://ledsmagazine.com/features/10/12/11

A very interesting article on the operation of dimmers and drivers which are designed specifically to be phase sensitive (whether in fixtures or bulbs.)
But it does not address the even worse problem of the older two wire dimmers which rely on conduction through the load and therefore are unstable when the impedance of the load is not constant.
In its least obnoxious form this is why an incandescent load will suddenly go out at the low end and not come back on until you have turned the control up to a higher level. When that type of dimmer is used in conjunction with the non-linear load of an LED driver you can get flickering and other more obnoxious effects.
But the article gives a good explanation of one way in which dimmers and drivers which are designed for "proper" interoperation can still be unsatisfactory.

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Most dimmers in North America new and old are two wire triad based. Even the three wire ones with neutral are still triac based and effectively as far as the load is concerned are two wire triad based.

Dimmers based on non triac switches are common in Europe where MR16 is more popular.

All triac based dimmers will cause issues for the load w.r.t. flicker/dimming issues due to hold current requirements of the triac and that interaction with the driver circuit.

I noticed that the drivers produced by this company still may require at least 2 loads in order to work properly and as well as only single voltage.

Semiman

One of the main reasons many LED bulbs only dim to 10%, which is still quite bright, is to eliminate flicker issues due to low loading on the triad. I have noticed that some SSL "compatible" dimmers dont go very low either.

Some "dimmers", particularly those used for fan speed control, actually contain an adjustment for the minimum duty cycle end of the range.


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Some of the newer high end dimmers allow you to adjust both the upper and lower max points.