# Dimmer Switches ...



## waldiddy (Aug 4, 2008)

I've got an effect in mind where I have 2 lights: red & blue tied to the same dimmer switch. I start out with 100% red and 0% blue, then slowly turn the dimmer and at the end, get to 0% red and 100% blue. 

Is this possible with 1 dimmer switch?


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## Erebus (Jul 28, 2009)

No it is not. You are talking about manual dimmer that people use inside their house, correct? If so, then no. When you turn the dimmer switch, it limits how much power goes though it. If you tie two lights on the same switch, the will both be on, and when you turn the knob, they will both dim.


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## Otaku (Dec 3, 2004)

I don't think one dimmer can do that. What you're talking about is a cross-fader. The effect can be done with two dimmers, though.


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## GhoulishGadgets (May 13, 2010)

Hi, 

It can be done easily, IF you're happy to re-wire the electronics in the dimmer.

basically, you need a dual gang dimmer (that's what they're called here in the uk, 2 dimmers on one plate)

here, they're typically two dimmer modules on the same plates, so you just remove the nut on one of them to remove it.

then you will see the control pot, the part with the spindle, typically on this there will be 3 connections next to each other in-line, the outer two are the ends of the resistor track, the middle is the wiper that travels from end to end of that resistance track.

it's a simple task to disconnect the end two connections and reverse them, so the left hand connection on the pot is connected the to right hand pcb point and the left is the opposite of that.

there may be a few other connections - if the dimmer has a switch option, just ignore these and leave them as they are.

then put it all back together, set both to either minimum or maximum, wrap an elastic band around the control knobs - tight enough that when one moves, so does the other... done and sorted

as one increases level, the other will decrease.

the other thing to note is that that pot (potentiometer) - the control component, can be one of two flavours - log or lin (typically log over here), this is the rate of resistance change across the track, lin (linear) means that the resistance change as the wiper moves is the same across the disance, log on the other hand starts with a slow change moving to a more rapid change in resistance across the track.

With Log type device, you will get a min-max crossover, but with a slight level variance in-between, but should be ok.

I have a dual gang dimmer in the garage, I'll dig it out and take some pics of the conversion process.

Si


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## GhoulishGadgets (May 13, 2010)

sorry, dupe post again, everytime I use quick reply it happens...
Si


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## The Pod (Sep 15, 2009)

Instead of a rotary dimmer, use a slide dimmer. Buy two like Otaku said and mount them both in a double gang electrical box but install one upside down so up is off. Then you just move both sliders in the same direction at once dimming one while brighting the other.


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## Otaku (Dec 3, 2004)

Another option is to use two rotary dimmers, mounted with the knobs (wheels) facing each other. Set one to full on, the other to full off. Tape or bond the wheels together. Rotate the bonded wheels - as one side dims, the other brightens.


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## DarkLore (Jan 25, 2009)

Otaku said:


> Another option is to use two rotary dimmers, mounted with the knobs (wheels) facing each other. Set one to full on, the other to full off. Tape or bond the wheels together. Rotate the bonded wheels - as one side dims, the other brightens.


Using two rotary dimmers sounds quite messy. There's already a post on the forum that pertains to cross fading lights, but I don't have a link for it.

I think photos would be great. Including an estimated pricelist of components if possible. I was considering something similar with rope lighting.

Cross Fader Thread


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## DarkLore (Jan 25, 2009)

As noted in the old thread....cross fading is useful for Pepper's Ghost effects, Ghost Paintings, etc.


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## Otaku (Dec 3, 2004)

I don't plan to build one, but I found 600W dimmers at Lowes for $4.97 each. A dual receptacle goes for about $1.25.

Explain messy?


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## DarkLore (Jan 25, 2009)

Otaku said:


> I don't plan to build one, but I found 600W dimmers at Lowes for $4.97 each. A dual receptacle goes for about $1.25.
> 
> Explain messy?


Mounting two slide dimmers side by side wouldn't be much different than mounting them to a wall joist with a switch cover. Using a commercial cross fader would be easy and unobtrusive.

http://www.digitalsl.com/products/lighting/selc/lc/lightingcontrolers.html

Mounting two dimmers to face each other, would lead to several "messy" problems to solve. 1.) ...mounting them to a surface while maintaining proper alignment. 2.)...gaining access to the control. Taping them together would hardly be durable...and I would presume to be a bit "messy" to join. Using a connector as described in the linked thread I posted earlier, would work...but you still have the access issue.

I figure there is a reason music DJ folks use sliders on their control panels for fading....because it's easy to grasp the concept and presents a fairly clean solution.

And, with sliders, you get the thrill of feeling like a U.S. Air Force jet fighter pilot, every time you push the fader throttle forward. Facing two dial controllers at each other would only be neat if you mount a large wooden lever in there, so Igor can pull the massive lever to initiate the fade. Therefore, this brings me to the conclusion.....Igor versus U.S. jet fighter pilot = messy.


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## Otaku (Dec 3, 2004)

Yeah, I knew about that fader and $30 isn't too bad. You don't get "on demand" control, though, you can only set a cycle speed. I use a similar one in a coffin.
Tape was just one option. Bonding the knobs together would be better, and I don't see any issues with getting the correct alignment. Keep in mind that this is just brainstorming - not a final solution by any means.

Igor? You know me better than that lol!


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## pshort (May 6, 2008)

Or mount the dimmers next to each other, with knobs that are touching (perhaps with a bit of rubber band on one of them to increase/control the friction). If the knobs touch each other, rotating one clockwise would rotate the other counter-clockwise.

Just a thought, I don't know how well it would work in real life.

Edit: or maybe use gears glued or otherwise affixed to the dimmer shafts...


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## Otaku (Dec 3, 2004)

Yep, that'll work, too.


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## DarkLore (Jan 25, 2009)

Now yall are crawling around in the dark corners searching to find a way out.

If I could get a couple pretty girls to dress in skimpy outfits, pulling and tugging on the knobs while breathing heavy and screaming, "I can do it for you master" - ya, that would pretty much sum up my ideal solution. And it would work. But I can't afford that, so I'm still offering up my prior recommendations as the best available, non-messy solution.

Just think how many neighbors would praise me for my holiday spirit and set out lawn chairs for next years display. And, nobody would give a damn whether the red light was on or the blue light was on. I think maybe I'm onto a new theme for next year.



Otaku said:


> Igor? You know me better than that lol!


I knew that'd getcha. Yes...I know you well enough. And I'm pretty sure wouldn't settle for gluing to light switches face to face.


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## fritz42_male (May 5, 2009)

DarkLore said:


> If I could get a couple pretty girls to dress in skimpy outfits, pulling and tugging on the knobs while breathing heavy and screaming, "I can do it for you master" - ya, that would pretty much sum up my ideal solution.


Know what you mean - I'm rather jealous of Chris Hanson getting up close and gruesome with 2 lovely ladies on his Scratch Built Corpse DVD.

I was lucky year before last, 2 mum's decided to turn up at our kids Halloween party dressed in rather skimpy costumes. I was dribbling all night - luckily it just added to my costumes effect!


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