I have newish beer signs in my restaurant and they give off too much light at night. I have asked the beer guys to dim them and they show me a little switch on the ballast that knocks the light down maybe 10%. Not enough.
Today I found some dimmers from 20 years ago that you plugged the neons into and simply dialed down the light, but I’m told that they won’t work with the new-tech ballasts and I’ll blow everything up. Anyone got a handle on this? Thanks.
If it turns out they aren’t sufficiently dimmable, could you construct a smoked glass/plastic cover and nail it up in front of the tubing? If you’re going for low lighting, that’d be the first solution that comes to my mind.
Hopefully someone else wanders by who knows more about neon light dimming!
Have you thought about putting in a dimmer switch. To do it easily it would need to be wired into a circut that has a wall switch. Replace the wall switch with a adjustable dimmer available at one of the local big box home improvement stores. The wall mounted dimmers vary the amount of power sent to the light. Reduced power should provide the result you are looking for.
Of course I am not an electrician or neon sign expert. But I really can see why this wouldn’t work. The lower the power going into the light the less bright the light will be.
You need a lower powered inverter. I had this problem, so I built my own, using a TV flyback transformer. It puts out around 1/10 the power of a commercial neon power supply, so the sign is a perfect brightness. You might try one of these. Just disconnect your current power supply and attach this one and see if it works (you really can’t hurt the neon trying this). Don’t try to dim a solid-state inverter.
I guess “don’t dim a solid-state inverter” is what I’ve been hearing. Problem is I’ve got about a dozen of them spaced around the place and they’re not really mine…they come and go at the whimsy of the beer suppliers, so I’m reluctant to start cutting them up.
So cutting down the 110v will or won’t help?
This won’t work for the same reason it won’t work for motors or traditional flourescent lights. The chopped-up power coming out of a plain lamp dimmer will not play nice with the internal power supply for a flourescent or neon light. Nor a motor. It will work fine with a plain dumb glowing filament bulb though. And that’s what they’re sold for.
There are certain “dimmers” made to work properly with motors like in ceiling fans. And there are special types of CFLs which have internal power supplies which can accept the chopped-up reduced power from an ordinary lamp dimmer.
It won’t work. Dropping the voltage on a neon light won’t make it dimmer, it’ll make it start to flicker instead.
So these little $10 magic inverters will reduce the light level substantially?
Output Voltage: 6kV to 7.4kV
Input Voltage Range: 113VAC to 132VAC
What do you suppose the current to the tubes is now?
What kind of mess will I be making if I put one of these in?
Unfortunately, they don’t post the current output for these inverters. Most neon signs run on 15mA or so. If this little inverter puts out 5mA, it will reduce the brightness substantially. The interesting thing about neon signs is they only require the high voltage to strike - after that, the power supply limits the current to some very small value, and the voltage across the sign is quite low. So, you need to find a HV power supply with a smaller current limit than the one you have now. This is the inverter I made - it only has five parts. You can mess with the resistor values and windings to change the current and voltage output.
I don’t think you will make any mess - just be careful.
Look into the filters used on stage lighting.
They are called ‘gels’ (from gelatin, which is what they were originally made from). They are now plastic. They come in large colored sheets, which are cut to fit into a frame on stage lights. You would probably have to build some kind of a frame to hold them in place.
They come in hundreds of colors; you would probably want something in the gray range to dim these lights. They are pretty cheap. With high-powered stage lights, they fade & have to be replaced fairly quickly, that probably wouldn’t be a problem with colored neon lights.
A major supplier in the US is Rosco. There is probably a nearby distributor (a stage lighting supplier) you can buy from.
It sounds like the distributor owns the signs. If the signs are all neon without any graphics, I’d be tempted to ask the beer guy if I could spray the signs with spray window tint.
The gray thing would be Neutral Density Filters (which can drop the light level of a source from one f-stop to three). But gels are temporary solutions. Something that is off-screen or off-stage, they dont “look nice” (and if you have any wind or rain outside, you’ll have to replace them). I dont know how the ballasts for a neon sign work though. You might want to PM Snowboarder Pro, I remember that he works as a light DJ in Vegas. Might be the most appropriate Doper to ask.
If the signs come and go at the whims of the beer companies, look into having some shallow boxes made up of smoked plexiglas to hang over the signs. You’d want to have these made large enough to cover the most likely largest sign to be hung in a given spot, rather than sized to exactly fit whatever’s there now.
Alternately, ask the jobbers to bring you signs straight from the smokiest bar in town so the tubing is pre-dimmed with nicotine. 
The problem that most beer signs now use electronic “transformers” and even with an electronic-compatible dimmer, you only get about 10% dimming - just seems to be the nature of the beast and a generally acceptable tradeoff for not needing a 20 pound iron-core transformer.
If these were your own signs, you could have the transformer replaced with a dimmable design such asthis one. If you’re really brave, you might be able to swap these into the beer company’s signs, but the voltages are hazardous and the wires are a bit on the fragile side, not to mention the glass itself.
Sorry, I don’t work with neon. I work with theatrical lights (moving lights and conventionals) and the consoles we use to control them.
It looks to me like beowulff and gotpasswords and others have the whole neon transformer thing down, tho. I haven’t dealt with that stuff in more than 15 years now.
I suggest that you put a piece of smokes or tinted glass where you need it. Those signs are expensive and messing with the current could cost you.