D0M3STIC LED bulbs in Par16

[Emmien]

Would a normal dimmable LED bulb work in a birdie connected to a Betapack 2?

 

 

I thought that LED bulbs need special dimmers for household use, so won't they need special dimmers for DMX control as well? I'm pretty sure the LED dimmers are just PWM, but the Betapack 2 isn't (I think).

[adam2]

If your d0m3stic dimmable LED lamp is dimmable on a standard d0m3stic dimmer, then it should be fine on a theatre dimmer, they work in basically the same way despite one being controlled remotely and one by a knob on the front.

 

If however your LED lamp needs a special dimmer then it is probably NOT compatible with a theatre dimmer. MOST LED lamps sold as dimmable for d0m3stic use are claimed to be dimmable with a standard dimmer. The whole point of the advertising of them is that they are a drop in replacement for incandescent household lamps, without having to replace or re-wire anything.

 

 

 

[musht]

Within limitations, won`t dim to zero and will start somewhere north of 10% intensity.

 

Might need a tungsten ghost load on the dimmer as well to take minimum load up.

[Emmien]

I have tried all my dimmable LED lights, and none of them dim properly on my light switch, even though the website says they should. I don't know how my light switch works. It is an X10 dimmer. I'm pretty sure it isn't PWM.

 

My Light-O-Rama controller dims it fine. This is a triac based PWM controller, for small loads, so I guess I can use that for it.

 

Are all theater dimmers resistive or are there some triac PWMs?

[alistermorton]

Apart from sinewave dimmers, they're pretty much all hard fired triac (or thyristor) based choppers. Just like your light-o-rama, except probably using rather bigger triacs (5A, 10A and 20A are very common sizes in small theatre racks, for example). Resistive dimmers are fossils. You'll usually find them in the museum.

 

As has been said, a d0m3st1c "dimmable" LED on a triac dimmer will not dim smoothly from 0% to 100% and back to 0% - there will be a dead band where the electronics in the LED base stop working - usually the LED will dim down to about 10%, but when coming up will not "strike" until a bit higher than that. At very low levels an LED may slowly pulse on and off as the leakage current charges up the control electronics in the base.

[boatman]

As musht says, you'll need a dummy load (60W BC lamp somewhere out of sight) and you might find that the pre-heat level on the dimmer is enough to keep the LED alive. It may need to be reduced.

[musht]

Theatre dimmers , hard fire, they keep triggering the triac to keep it on. Lot of lesser dimmers just trigger the triac on and rely on sufficient load to hold it on until the voltage goes through zero point and triac switches off.

 

Dimmers are`nt really Pulse Width Modulation, thats for D.C., most dimmers are leading edge they switch the triac on through a mains half cycle, later in half cycle , less average power ,dimmer lamp.

 

Trailing edge dimmers, rare in theatres , use heavy duty transistors and switch the mains voltage off during the half cycle, this plays better with the driver electronics in line voltage LED lamps.

 

X-10 is getting long in the tooth, originally developed in Glenrothes, same design team came up with the Accutrac a vinyl turntable with track selection.

[Emmien]

I am pretty sure my LOR dimmers are Trailing edge.

 

I can just use that because it has a lot of channels and can handle enough load for a bunch of LED bulbs.

[alistermorton]

I am pretty sure my LOR dimmers are Trailing edge.

 

If they use triacs (which you've already said they do), they aren't. They're leading edge. As said, trailing edge dimmers use MOSFETs or other transistors.

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[boatman]

I am pretty sure my LOR dimmers are Trailing edge.

 

If they use triacs (which you've already said they do), they aren't. They're leading edge. As said, trailing edge dimmers use MOSFETs or other transistors.

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... and a large bridge rectifier!