triac dimmers in parallel

[DH]

Hi All,
I was wondering if any one here had experience with multiple
triac dimmers in parallel? I have a light track that at times has
twelve 100 watt incandescent bulbs (120v/60hz) running at full to zero
from a single rheostat. I need to replace the fixtures and was
wondeing how messy it would be to put a triac dimmer into each
fixture. The brightness is generally changes only when the lights are
moved on the track so I don't need convinient access. The next step
would be IR controlled but working is better than cooler right now.
This could perhaps be a nice cheap way to have many brightnesses on a
single track. The explanation of my use is because I don't know what I
don't know. I'm wondering if there are any problems with running so
many lil' clippers on the same circuit. Any guesses on how audible
they would be? if at all. They would all be shutting off at different
times (as in not at precisley the same time)- Would this generate
worse or more RF noise than a single unit dimming the whole track?
Would it be finally that frequency needed to talk to aliens? Is it
stupid? Also, Even at full does a triac dimmer drop the voltage?

Thank you all!
DH

 

[James Sweet]

Hi All,
I was wondering if any one here had experience with multiple
triac dimmers in parallel? I have a light track that at times has
twelve 100 watt incandescent bulbs (120v/60hz) running at full to zero
from a single rheostat. I need to replace the fixtures and was
wondeing how messy it would be to put a triac dimmer into each
fixture. The brightness is generally changes only when the lights are
moved on the track so I don't need convinient access. The next step
would be IR controlled but working is better than cooler right now.
This could perhaps be a nice cheap way to have many brightnesses on a
single track. The explanation of my use is because I don't know what I
don't know. I'm wondering if there are any problems with running so
many lil' clippers on the same circuit. Any guesses on how audible
they would be? if at all. They would all be shutting off at different
times (as in not at precisley the same time)- Would this generate
worse or more RF noise than a single unit dimming the whole track?
Would it be finally that frequency needed to talk to aliens? Is it
stupid? Also, Even at full does a triac dimmer drop the voltage?

Thank you all!
DH

You should be fine to do that, though that's not really in "parallel" (which
would definitly be a bad idea), so long as you can find a dimmer that will
fit in the head.

 

[NSM]

| Hi All,

| Also, Even at full does a triac dimmer drop the voltage?

Imperceptibly.

N

 

[Aldo Larrabiata]

Some years ago, I was involved in dimmer development.
Triacs may be connected in parallel but it's pretty hard to synchronize the
gates and the voltage drops must be compensated by series resistors
dissipating huge amounts of power with regard to the triacs' power losses.
Even considering the suppressor inductor, the circuit isn't optimized.

On another hand, if you have a low power dimmer, it's pretty easy to modify
it, adding a 25 or 40 Amps triac, like a Darlington.

The RF noise is mainly related to the voltage transients during the
transitions produced by the triac, you'll need a bigger coil, dealing with
the overall current. Of course, switching high currents will also cause
differential conducted perturbations. Computing a suppressor circuit isn't
easy. Better to look at the manufacturer's catalogs.

At full, the voltage drop of a triac is around 1.5 V. However, most of the
dimmers are two wires. The electronics is supplied by the voltage taken from
the triac's electrodes. Hence the max duty cycle is not 100%. But due to the
non-linearity of a bulb, this is completely transparent. You can decrease
the voltage of 15 V, the effect is negligible.

 

[Sam Goldwasser]

You should be fine to do that, though that's not really in "parallel" (which
would definitly be a bad idea), so long as you can find a dimmer that will
fit in the head.

There are 1200 W dimmers readily available. That would be a simpler
solution if you don't really need individual control.

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[James Sweet]

There are 1200 W dimmers readily available. That would be a simpler
solution if you don't really need individual control.

I thought that was the idea though, that he wanted individual control?
Otherwise yeah, just get a higher powered dimmer, they're not terribly
expensive.