Looking for a CFL design

[alphacat]

Hey,
Thank you very much for the great info about CFLs in the previous thread.

I'd like to build a "CFL driver" that would fit any watt rated CFL.

Where could I find articles/app notes that include schematics (and explanations) of CFL drivers?

Thanks a lot.

 

[tcmtech]

Dont all CFL's come with the power supply circuit built into them now?

 

[EN0]

Dont all CFL's come with the power supply circuit built into them now?

Yes, they do. You could break one open and find a small circuit board with discrete parts. This, however, is not recommended; CFLs have mercury vapor which is harmful. When DC electricity goes through the mercury vapor it creates UV light. This in turn is filtered by the white coating inside the glass which makes it into pure "white" light.

Austin

 

[Sceadwian]

alphacat you'd need one that has the ability to vary it's total wattage, generall the driver circuits are designed around the tubes so you can't really have a universal solution, nor should there be any need for it, a low wattage CFL inverter should be more than enough to test basic functionality of any gas filled tube.

EN, CFL's arent' that difficult to take apart, even the ones that are welded shut are easy game if you have a dremel tool and a steady hand, it's very easy to avoid breaking them, they're designed to be modestly tough.

Also just a few notes. CFLS run off AC not DC, and the mercury vapor is only harmful if you breath it =P. It's a pretty simple rule to keep reminding yourself, if you ever break a mercury lamp simply stop breathing and slowly walk away, there's very little risk, more risk from getting a shard of glass in the eye when the tube implodes. Also, fluorescent lamps don't actually produce white light, they produce a few narrow bands of light which approximates to the human eye to look white, that's why CFL's generally only have a CRI of 70-80 where an incadescent bulb has a CRI of 100 because it produces a very broad spectrum of light.

 

[audioguru]

When DC electricity goes through the mercury vapor it creates UV light. This in turn is filtered by the white coating inside the glass which makes it into pure "white" light.

No.
Compact fluorescent light bulbs have a power oscillator that feeds the light AC at about 40kHz, not DC.

No again.
The bulb produces ultra-violet light and the white coating is a phosphor that glows white when it receives ultra-violet energy.

 

[tcmtech]

To clarify my point how or where are you getting the tubes for a home made CFL? Thats what I am curious about?

I have taken many apart and they are typically just snap together plastic bodies. just pushing a small screwdriver between the seems and twisting is enough to get most open.

As far as the Mercury vapor its not actually a vapor until its electrified and converted into a gaseous plasma state. In a cold bulb its just microscopic droplets that stick to the ends around the electrodes and sides.

The problem you may run into with making a variable power CFL driver is that each bulb takes a combination of different current and voltage to work right. But being variable it would give you the possibility of making a normally non dimable CFL dimable as well.

On one aspect of CFL's if you could come up with a way to produce a higher striking pulse voltage and driver circuit so that the two end filaments dont need to be used you could conceivably run some old CFL tubes a bit longer.
I have found that about half of the dead ones I have had the starting filaments burn out but the bulb itself will work fine when powered off of a lower voltage neon sign transformer.

 

[audioguru]

They design the bulbs so that the filaments burn out in a year or two so you must throw it away and buy another.
They lie about them lasting for 10 years.
Guess where they are made. China.

 

[HarveyH42]

They design the bulbs so that the filaments burn out in a year or two so you must throw it away and buy another.
They lie about them lasting for 10 years.
Guess where they are made. China.

Do you think Canada would give you free, 'High Quality' American made bulbs? Of course they are made in China. I got a hunch most lights are made with a short life span, they want you to continue buying them. Not much future in building something that will last forever.

 

[audioguru]

Do you think Canada would give you free, 'High Quality' American made bulbs? Of course they are made in China. I got a hunch most lights are made with a short life span, they want you to continue buying them. Not much future in building something that will last forever.

My Osram/Sylvania CFL bulb failed early. I called their customer service and they took my address. Then a box full of them came that were made in Germany, not China like the one that failed.

A few more Chinese bulbs failed early and now their customer service is not down the street, it is in southern USA where they can hardly speeky zee English (African?). They sent me a coupon for one but the minimum package has three.

 

[HarveyH42]

I was of course joking, most American made stuff has an usual habit of failing months after the warranty expires. Happens way to frequently to be coincidence. Chinese stuff breaks quickly, because shipping it overseas costs more than buying another one. African, sure it wasn't Spanish? Seems like our new national language anymore, and I only have learned a few phrases from work, which probably aren't too appropriate.

 

[alphacat]

So there is no way to design a generic CFL's driver that would fit all CFLs?

 

[JimB]

So there is no way to design a generic CFL's driver that would fit all CFLs?

Probably not, but then why would you want to?
These things are produced in millions, so there is no particular advantage to the manufacturer to have a compromise generic driver.

JimB

 

[alphacat]

alphacat you'd need one that has the ability to vary it's total wattage, generall the driver circuits are designed around the tubes so you can't really have a universal solution, nor should there be any need for it, a low wattage CFL inverter should be more than enough to test basic functionality of any gas filled tube.

Isnt there a power supply that you can build which can provide a range of watts to drive different kinds of CFLs?

 

[alphacat]

Probably not, but then why would you want to?
These things are produced in millions, so there is no particular advantage to the manufacturer to have a compromise generic driver.

JimB

Yes, you're right.
I thought of building my own CFLs and drive them with my PSU.

 

[BrownOut]

I have a simple design for a CCFL supply from a recent publication. It's not the most efficient design, but it's a starting point. I would say that rather than try to build a universal supply, start with a basic design and optimize for the bulb you're using. Designing the supplies are easy, getting proper magnetic components might not be so easy.

 

[tcmtech]

I have several different wattage units all from one manufacture and the power supply layout is basically the same from smallest to the largest. Its just a few capacitors, resistors, and coils that are different.
The actual circuit layout and schematics are the same. They just tweak them for slightly more or less power in reference to each other.

For my experience with CFL's the American made ones do fail a suspiciously short time after the warranties are up just like most American made stuff seems to now.
I have bought 4 packs of an American made brand and all four died in the same kitchen and bathroom fixtures within about one weeks time of each other in said fixtures. Once the first one went out all four where dead within a normal weeks use.

The Chinese ones I replaced them with one out of the 8 went out the first day and the other 7 are about 3 years old and used every day.
The Chinese ones either quit the first day or last for years. They dont seem to have much in between unless they are in too hot or too cold or harsh environment for their design.

Unfortunately thats also where so many CFL's regardless of manufacture die at. No one reads the box and finds the ones designed for their intended application.

They do make them in cold, hot, and harsh environment designs if you bother to go and look to find them. If it doesn't say specifically rated for XX degrees below zero or above XXX degrees its a generic middle range unit that will die right away when used in a place that too cold or too hot!

 

[tcmtech]

So where are you going to get bulbs that dont already have the power supply built in?
The only ones I have found on the shelf that dont have built in power supplies are the replacement 40 and 65 watt units for my yard lights. I have not seen any smaller than that that dont have a power supply built in.

Unless your planning to use the mini strait tube type that are in under cabinet lighting fixtures.

 

[mvs sarma]

So where are you going to get bulbs that dont already have the power supply built in?
The only ones I have found on the shelf that dont have built in power supplies are the replacement 40 and 65 watt units for my yard lights. I have not seen any smaller than that that dont have a power supply built in.

Unless your planning to use the mini strait tube type that are in under cabinet lighting fixtures.

we too get Chinese stuff but marketed by branded companies. perhaps they insist for some QC, they are serving us for almost an year.

 

[Sceadwian]

alphacat what is the purpose of creating such a wide ranging power supply for fluorescent tubes?

 

[audioguru]

Aren't we talking about little compact fluorescent light bulbs that are used in homes, not fluorescent tubes that are used in stores?
13W compact fluorescent light bulbs cost about $1.00 each when on sale so why bother making them?