Compact fluorescent circuit

[davej]

I'm talking about the CFL's used to replace incandescent globes. Is it possible to take, say, an 18 W CFL, dismantle it and use the controller circuit to run a regular linear 18 W fluorescent tube? If so, wouldn't it be more efficient than the typical magnetic ballast?

 

[audioguru]

The filament voltages and currents will be different. The high voltages will also be different due to the different lengths of the tubes.

An 18W fluorescent tube uses such a low amount of power that little is gained if an electronic ballast is made for it.

They make new fluorescent tubes that are 48" long and use 34W or 40W in a new smaller diameter and with different pins spacing from older ones and have very efficient electronic ballasts for them. The tubes last much longer.

 

[Nigel Goodwin]

The tubes last much longer.

But probably only in 110V land?.

 

[CheapSlider]

It is possible.

I have done this using a 13W CFL ballast to drive a 13W linear tube. The measured power consumption was 12W.

Fluorescents are supposed to be about 10% more efficient when driven at a higher frequency. I have no means of measuring but the brightness appeared similar to a magnetic ballast. (It's very hard to assess brightness due to the fact that the eye is very good at adjusting to different lighting conditions).

I have no idea if there may be any long term effects on the life of the linear tube due its being driven harder by the CFL ballast.
Main cause of ballast failure in a CFL unit is due to the heat from being next to the tube. The ballast can be located away from the linear tube to prevent it getting hot

Without access to a free source of discarded CFLs (from which the ballasts could be removed) I doubt if would be worth doing. CFLs are available very cheaply especially if a lookout is kept for promotions or offers.
There does not seem to be any point in buying a CFL just to remove the ballast.

These may be of interest **broken link removed** also CFL ballast circuits

 

[Ocelaris]

When dealing with the electronic ballasts, there are problems with mounting them remotely, namely, 2' ~80cm is the max distance you want to mount the ballast from the bulb because of increased capacitance...

Advanced Transformer has some good information on their electronic ballasts... which I believe is owned by Philips lighting, NAM etc...

http://www.advancetransformer.com/uploads/resources/2006-07_Advance_Atlas_Section_2_Electronic.pdf

But the most useful page was the bulb manufacturer, USHIO, spec page for their CFL bulbs...

**broken link removed**

It has the operating voltage and current rating for various biax (2 pole) or other multi tubed CFL bulbs... so you can presumably determine which ones have the same voltage and/or current to operate...

The general understanding I have is that tube length determines compatability... meaning a bi-ax 2 tube bulb of 18" length = 36" total length, will generally run on the same 36" tube T-8 electronic ballast...

But I have no idea how some ballasts will run different length bulbs, can anyone explain that? I bought a couple dimming dual 24w Advanced transformer electronic ballasts on ebay for silly cheap, and it says it will run 18, 26, 32, or 42w bulbs... the current ranges from .220 to .320, and voltage from 100-135v respectively... so not sure how it auto-selects?

Electronic Metal Halide ballasts are terrible if you mis pick the bulb to ballast... for example the 150w bulb has 3 different voltage specs, the older versions ran a higher voltage, but some of the newer ceramic bulbs run a lower voltage, but pulse start... which meant basically it couldn't ignite the bulbs, but eventually the bulbs would explode because of overvoltage across the arc tube... I don't think that's a problem with CFL, but just saying specifying the wrong ballast for the wrong bulb can cause rupture... so be careful.

Ebay is your friend, I ended up with 4 of these dimmable ballasts (normally 50-75$) for 10$ a piece, 4 bulbs for 8$ a piece 42w, 4100k, 82CRI, and 4 sockets all for about ~100$, ~25$ a piece... for 80 lumens/watt light source. These are instant on supplements to my Metal Halide 100w bulbs I have in the rooms...

 

[davej]

Thanks everyone.

An 18W fluorescent tube uses such a low amount of power that little is gained if an electronic ballast is made for it.

I was thinking of overdriving them a bit but don't know if that's possible or safe with the CFL circuit.

I doubt if would be worth doing.

In the name of recycling I have a few laying round the place. I was trying to compare the efficiency, costs, and risks of using the CFL ballasts to buying a proper multi-tube electronic ballast. But obviously you get a lot more features and safety with a commercial setup. And thanks for the links.

When dealing with the electronic ballasts, there are problems with mounting them remotely, namely, 2' ~80cm is the max distance you want to mount the ballast from the bulb because of increased capacitance...

Not any more. When searching for electronic ballasts I found a few that could be remote mounted a fair way away. One is the range of GE UltraMax ballasts. The instant start models can be up to 18 feet away, while the rapid start can be 12 feet. Well, that's what GE say in their ballast catalog.

In the end I don't think it's worth it. I have read that many of the CFL ballasts are made to "self-destruct" after a while so they don't keep working after the tube has died. Think I'll try to get my hands on one of those GE ballasts. A lot safer idea, don't you think?

 

[Hero999]

A CFL ballast won't power a standard fluroscent tube of the same wattage because the dimensions are totally different. An 18W linear fluroescent is wider and shorter than an 18W CFL which is narrow and coiled up. Longer tubes require a higher voltage and wider tubes require a higher current therefore your ballast won't provide enough current to your linear tube and the voltage will be lower which might cause the ballast to overheat.

 

[davej]

A CFL ballast won't power a standard fluroscent tube of the same wattage because the dimensions are totally different....

I don't think I'll go ahead with the plan now, but the first link CheapSLider posted shows it is indeed possible. About a quarter of the way down the page the guy explains how he did it, and how it ran for 8 years (guessing fairly intermittent use). Whether the same could be done with higher wattage tubes is another thing though.

 

[mvs sarma]

Why not givea try Devaj, afterall a salvaged part. you gain experience. -- may need HF choke mod with thicker wire. and few cahnges for Transistor / mosfet(if used) to be replace by littel higher wattage.like BU505

 

[Hero999]

I don't think I'll go ahead with the plan now, but the first link CheapSLider posted shows it is indeed possible. About a quarter of the way down the page the guy explains how he did it, and how it ran for 8 years (guessing fairly intermittent use). Whether the same could be done with higher wattage tubes is another thing though.

I haven't read that yet.

Don't get me wrong I'm sure it's possible, powering a fluroscent tube is easy. However: will it power the tube at full brightness? Will it give maximum tube life? Is there a chance the ballast might overheat?

You can power a fluroescent tube from a simple single blocking oscillator but the tube doesn't work at full brightness and tends to go black at one end.

You can even power a fluroescent tube by standing it under a power line but it will flicker.