cold cathode dimming

Want to know more about dimming cold cathode (CC).

In general, what's the main technical difference in dimming universal dimmable cold cathode transformers and say, leading edge transformers? I don't have specific brand in question, but I guess there is something fundermental different.

Why Professional Dimmers require NEON adaptors for CC dimming, whiles other units do not need? What does the adapter do? What happens if it is not used when dimming CC with professional dimmers?

Apart from C-Bus dimmers, what else can we or can't we use for CC dimming?
For example, simple clipsal Rotary dimmers; wireless C-Bus dimmers...etc...

 

The CC tx is normally a step up from 240V to some kV level. The ones I have come across have all been iron core so dimming them with Leading edge Phase Angle control SHOULD be straight forward, BUT two spiders are in that particular fruit bowl, 1, the neon load is typically fairly high impedence so a small amount of secondary current is all that is needed to keep the Neon glowing, 2, most dimmers have an amount of off state leakage current that is required to allow them to meet EMC regulations on radiated electronic noise.

Put those 2 together and you have the situation where at low dimming or even off state there may be enough leakage current to keep the neons running/flickering.

The CC adaptor that fits to C-bus PRO dimmers simple acts as a current sink to limit/remove any significant primary current in the step up tx.

Pretty much the same effect could be expected with any EMC complient Phase Angle Control Dimmer but slight variations in design and what the total load current for that particular dimmer channel is may result in some make and models being less suseptable and my memory tells me that by and large the DIN range of dimmers do not require the CC adaptor (but it may be required with some make and model CC tx).

 

Something else to watch out for is that there are an increasing number of electronic transformers for cold cathode lamps entering the market. These are generally cheap but not dimmable.

It seems to me that the dimming of cold cathodes is at a similar stage to where low-voltage down-lights was about 5 years ago. Most of the early electronic LV transformers were not dimmable and even some iron-core trannies could not be dimmed. It's a similar situation with cold cathodes now.

The DIN dimmers are generally OK with iron-core ballasts on CC lamps however if they're not then the neon lighting adapter solves the problem 9 times out of 10.

The new DIN universal dimmer has been tested on a range of iron-core and electronic ballasts for CC lamps and all iron-core units worked fine however some electronic ballasts required the NLA and others didn't dim smoothly even with the NLA. This gets back to the design of the electronics inside the transformers not being compatable with phase control dimming.

 

Any test on wireless c-bus dimmers with these kind of ballast? While Wireless C-Bus has significant leakage current too, could we use a NLA for CC dimming?

 

A C-Bus wireless unit is certainly capable of dimming a Cold Cathode lamp & ballast provided that the ballast for the lamp is compatible with phase control dimming. The NLA will most likely be needed. As I stated earlier, at the moment it's a bit pot-luck as to whether an electronic CC transformer can be dimmed. Make sure you use the correct Wireless dimmer type - LE for iron-core ballasts and TE for electronic ballasts.

 

not flickering cold cathode???

some one pls help me, i have just install a cold cathode,the lenght of that cold cathode = 3 meter, the surounding it about 5cm. what i want to ask it's how to make the cold cathode not flickering in a low dimming??? i use an electronic ballast. and how the percentage of minimal dimming, is it possible to dimm down to 1%?

 

Is your electronic ballast compatible with phase control dimming? If you don't know then the answer is probably not. You may be able to get it to work by adding the 5100NLA but there is no guarantee. Because you are using an electronic transformer, which work best with trailing edge dimming, your chances of success would be increased if you used the C-Bus Universal Dimmer, but it's still no guarantee.

 

thanks newman for the answer, but the problem is, i'm not connected it to a c-bus, but just connected it to an ULTI dimmer.. i have try to add an 5100NLA but there is no effect. actually which type is the ULTI dimmer, is that leading edge or trailing? i also have try to change the e-ballast with a conventional ballast, its not flickering but still remain about 10% current,and the ballast its huge. so i decide to use the e-ballast?? give me some advice plss

 

I think ULTI is not sold in Australia and they probably tranform them into wireless C-Bus (just my guess). Ulti has different model/type/version for different countries during different period, and you should try to find an answer from your dealer. Anyway, most likely they are leading edge Dimmer (The unsal model, with big power unit). Depending on their EMC type, (EMC model and non-EMC model) they may behave a bit different too.

I don't think Ulti can dim a Cold cathod porperly, because it is never in their compability chart. So the best you can try, according to the posts in this discussion, is to connect the dimmer to 5100NLA and conventional ballast. Ideally it should not flick and the NLA should be able to handle some of the leakage current. However, with the small load limit of Ulti dimmers, you have to make sure, with the power loss, the conventional ballast doesn't overload the dimmer itself.

If you have a type 2 Ulti dimmer (smaller in size), you may try to program it to a Trailing edge dimmer (Type 2 is an universal dimmer, and you can force it to LE ot TE, I think), and try the e-ballast.

These are what I would like to try later if there is no formal testing result from Clispal.

By the way, I am not CC expert but I think CC will flick under 5% or 10% (depending on the ballast again) with most dimmers.

 

In the ULTI / EZInstall product range there is both Leading Edge and Universal dimmers available. In the MK1 product range the dimmers are LE only. In the MK2 product range the Universal dimmer is available, which automatically switches between LE and TE dimming based on load type. If you have an eletronic cold cathode ballast then you have the best chance of it working with a Trailing Edge dimmer of some kind. If you have tried the 5100NLA without success then you can try changing the dimmer to the ULTI universal dimmer or a C-Bus Wireless TE dimmer. They may still need the 5100NLA. If that still doesn't work then you'll need to change the ballast to one that is compatible with dimming.

Note: C-Bus Wireless and ULTI have nothing in common.