From everything I read about, it seems to be agreed that LED black lights do not have nearly the same effect as fluorescents. But I need something DMX controlled, any suggestions or comments??
Original Post
Did you want suggestions for LEDs? Or for the other kind? We have a uv wash and it is not led. Check it out. Not too sure if it dims though.
Not 100% true jingles, you can dim fluorescents with a Sine Wave dimmer, which are very expensive.

All light sources emit UV. Nothing has the same effect as fluorescents because fluorescents output a lot of UV do to design. So much so that they are used to sterilize things. All fluorescents have a coating to block UV so it doesn't hurt anyone. Black light fluorescents don't have as strong a coating, allowing save levels of UV out. They are also colored purple because UV has no color technically. The purple color is a safety feature to know when they are on or off.

LEDs also put out UV, just not nearly as much. 'White' LEDs are actually UV LEDs with a coating to block UV so they look 'white' if I remember correctly.

You can also try UV filters on dimable lights. Companies like Apollo and Rosco make glass filters that block a lot of visible light and only let UV through. They still aren't as effective as fluorescents, because they are designed for visible light, not UV. UV is just a by product. They also still let some visible light through, so you get a glow. Very dark blue and purple gels can also give a UV effect, but again, they still have a glow.
We have controlled fluorescents with our lighting system by simply changing the dimmer to non-dim mode (it comes on full when the channel is at 50% or more - like a light switch). Would this work in your situation?
Originally posted by SerraAva:
You can damage your dimmer and/or the light that way, so I would not recommend it.

How would this damage the dimmer or the light? We have a neon light on one of our dimmer channels (new ETC rack) and the technician didn't have any problem setting up non-dim channels, plus the dimmers actually have a fluorescent setting on them that does the same thing. For the light, what does it care if the power is "switched on"?
I apologize in advance for the very long and off topic post I am about to post.

SCR dimmers work by chopping the sine wave of AC. This is how they 'dim'. AC is a wave.

DC is a line.

Now when power is created, is is created by a magnet spinning in a coil at 60 times per second, thus 60hz AC. This is how and why the wave is created. The little sine wave above, the start as 0 degrees, the first peak point as 90 degrees, the next mid point as 180 degrees, and the bottom peak point is 270 degrees on our spinning magnet. This is what makes the wave. Motors take AC and use the wave to work. Picture a piston. It will be in the middle at 0 degrees, one extreme at 90, back to the middle at 180, and the opposite extreme is 270, then back to zero. It's this cycle that let's your piston move up and down evenly and predictably.

Now what does this have to do with SCR dimmers? SCR dimmers work be varying the voltage for your lamps to dim. At 50% on 120v AC, you will be using about 60v. 25% would be 30v, so on, so forth. It does this by chopping the sine wave. How it does this is by turning on and off the power every millisecond. So your wave will be flat, then peak, go down gradually to the next peak, then instantly flat again.

Now remember our piston and the circle, between 0 and 89.9999999999 degrees, no voltage, it sits still. Then all the sudden, peak voltage and it slams to the one extreme. Back to the middle at 180 and next extreme at 270. Then at 270.00000000000001, no voltage instantly and your piston is sitting in the middle again. This is very bad for the motor, because instead of working smoothly, it is getting extreme, sudden changes, and works much harder to do what it needs to do, using more amps, and heating up the piston and dimmer in the process, and heat it the enemy. It is what causes things to break.

A simple way to explain it, stand still, then start running full speed instantly, continue, then just stop just as instantly. Do this 60 times a second and see how you feel.

Now if the dimmer is is doing this, why don't your lights turn on and off while dimmed? Well, since this is doing it 60 times a second, it is not enough time for the lamp to warm up and cool down again, so you never even know this is going on. The buzzing noise that you hear when you dim lights or run your lights below 100% is proof of this. This is also why it's the loudest at 50%, because this is the worst the sine wave is chopped.

I have to go off on a gig now, will return to post some more on this later.
Continuing on now:

The buzzing noise is known as lamp sing, it's caused by the power being turned on and off really fast. The way this is fixed is more expensive dimmers have what is known as a choke after the SCR so the power change is as dramatic as on/off. The better the quality of dimmer, the less lamp sing you will get.

Now why non-dim isn't really non-dim. Despite you setting a dimmer to non dim, either via the pack or the console, the power still passes through the SCR and choke. So, the power is still being turned on and off extremely fast. Now there are more modern dimmers that by-pass the SCR and choke when switched to non-dim on the dimmer itself, making it a true non-dim dimmer.

I believe Elation's DP-640B dimmer pack is an example of this, but without a wiring diagram to look at, I can't be sure. Maybe jingles or Elation_Pro can comment on this and answer this for us.

Now why are things like fluorescents bad for the light and/or dimmer. First, in-rush currents. An in rush current is caused by a lower resistance in the circuit. This is caused by cold filaments in tungsten lamps. A filament's resistance can be as much as 1/17th of what it is when it is hot. Remember, heat is the enemy, more heat, more current, more chance for things to break. Let's look at Ohm's Law and the Power real quick to understand this. Warning, this next section contains use of algebra Wink.

Ohm's law states that V=I*R where V=Voltage in volts also sometimes displayed as E, U, or emf, I=current in amps, and R=resistance in Ohms. Power is P=V*I, where P=Power in watts, V=Voltage in volts, and I=current in amps.

Let's take an Opti-Par lamped at 575w. Now in the states, our AC is 120v. So, 575w=120v*I or 575w/120v=I and I equals 4.79 amps. So now we go to 120v=4.79a*R or 120v/4.79a=R and R equals 25.05 Ohms. Remember when I said something cold has less resistance, here's where is comes into play. If I take that 25.05 Ohms and divide it by 17, I get 1.47 Ohms, or 1/17th of the lamp's warm resistance. Now, back to our formula: 120v=1.47Ohms*I or 120v/1.47Ohms=I and I equals 81.63 amps. PS, the symbol for Ohms is the Greek sign for Omega, or W in English.

Now the question is, if you have a 20 amp breaker, how come it doesn't trip with 81.63 amps going through it. The reason is the lamp warms up so fast, it doesn't even register. Fluorescents have a longer warm up cycle, about 30 seconds or so. The fluorescent pulls more juice longer. Remember, heat is the enemy, while the heat is power given off, but the heat is caused by current. The more current, the more heat. This is proved easily. Plug in a quad box to the wall with a 20 amp breaker, or even a dimmer with 2400w per channel. Then plug 4 575w lamps into it, provided your power is exactly 120v, if not, 3 will do. Then plug just one into the wall with an extension cord. Let them sit for about 10 minutes or so, then go back and feel the cables. 3 or 4 times the lights, 3 or 4 times the current means much more heat.

Next, remember the turning on/off extremely fast, fluorescents don't like this. They want constant power. The extreme, sudden changes in voltage may damage it because: A) it is designed to work between 100-120v because B) the internal parts are designed to handle a certain amp load and with C) sudden, fast, voltage drops, the light will pull more current to keep working but D) won't trip the breaker because of how fast this is happening all the while E) more heat is generated because there is more current now and finally F) heat is the enemy and what causes things to break.

The UV Wash is 100w. Warning, more algebra ahead: 100w=120v*I or 100w/120v= I and I equals .83 amps vs 100w/90v=I and I equals 1.11 amps. Now, what happens when the voltage drops to 1v, thats 100 amps going through something meant for 1.11 amps at the most. 100x the load. But again, this is happening so fast that breaks won't trip and you won't even see the light turning on and off.

This is why anything that is not a lamp with a filament should be plugged into a normal dimmer.

Now, Pacman, you had mentioned that you had new ETC dimmers. First, ETC is the number one dimmer manufacturer in the world, or at least rated as such. Second, there are Non-dim dimmers that ETC makes. Third, some modern dimmers have a fluorescent setting. Fourth, ETC might now make a dimmer that bypasses the SCR and choke for non-dim mode. Finally, ETC also makes Sine Wave dimmers which actually dim the wave instead of turning it on and off via a SCR circuit, which can safely dim just about anything.

Any more questions? I will be more then happy to answer them. If you haven't figured it out from the past two posts, I am a physics and math junkie. I use this (math and physics) all the time to check power situations, like loading 3000w worth of lights onto a 2400w (20amps at 120v) dimmer and not tripping 15 amp wall breakers.
Last edited by serraava
Thanks SerraAva for taking the time to explain this. I guess we have been lucky the few times we have used fluorescents on our dimmers. Our neon light continues to function well without use of a special dimmer (and it is 12 years old now), but we are looking to replace it soon with some LED lighting so we can get rid of the high voltage transformer which causes noise on any electric guitars that get too close.
And again, nothing might ever happen. The same time, it might be affecting the dimmer and you don't know about it. It over heats and starts to blink on filament lights, and that might be caused by using neons, fluorescents, etc. You won't see anything blow up and go down in flames, the issues are more likely to be unseen, your neons and fluorescents might burn out early, ghosting dimmers, or you might be very unlucky and have the things stop working.

Just as a general rule of thumb, don't plug things besides filament lights into dimmers.

Add Reply

Link copied to your clipboard.