need help for cfl lighting

[pier]

i need help to make a circuit which consumes very less current for lighting up a cfl tube (9watts) with starter from a 6 volt battery . please help me .

[audioguru]

9W for the light tube and maybe as much as 1.8W for the voltage stepup circuit is a total power of 10.8W.
Therefore the current from a 6V battery is 10.8W/6V= 1.8A. Do you have a huge battery to supply a current so high?

[pier]

i saw a circuit that has few components and has a 9 watts cfl tube, but the whole circuit pulls only 700mA from a 6volt 4Ah battery . That is why i asked for it . please do help me .

[audioguru]

700mA from a 6V battery is only 4.2W. The inverter is about 80% efficient so the 9W bulb gets only 3.36W. That would be quite dim. Is that what you want?

[pier]

that is not a bulb . it is a compact flurocent lamp(tube) with a built in starter . while it starts the lamp flickers about 2 to 3 seconds then goes to steady state

[audioguru]

A compact fluorescent light needs a ballast to make it work. A very old ballast was a big coil of wire as an inductor, then it had a starter with mechanical contacts or a small neon bulb.
Modern ballasts are an electronic circuit with a power oscillator driving a high frequency small stepup transformer and a high voltage current limiter.

Our projects section has two projects that light small fluorescent tubes. The 1st project uses a 6V or 8V battery and its bulb is about 9W but doesn't say. It uses a transformer but the project doesn't show it or say any spec's about it.
The 2nd project is similar but needs a 12V battery.

http://www.electronics-lab.com/projects/motor_light/002/index.html
http://www.electronics-lab.com/projects/motor_light/027/index.html

[pier]

no that dosnt work out . i really need it from a 6 volt battery that draws less current . please try to help me cause i am badly in need of it .

[audioguru]

The only way to reduce the battery current is to reduce the circuit's power output. That makes the light tube less bright.

[pier]

but will that effect the brightness of the tube ?

[audioguru]

but will that effect the brightness of the tube ?

Of course. It takes power to make light. Less current from the battery is less power so is less the amount of light.

[pier]

but the circuit i saw was bright enough and draws only 700 mA from the 6 volt battery . I think BPL has started one without starter in the tube . how does that work then ?

Ive attached an image of the tube . u can have a look at it .

[audioguru]

I have lots of newer compact fluorescent bulbs in my home. The tube is a spiral. Most use 15W and a few use 23W.

The electronic ballast which is part of my bulbs pre-heats the filaments at the ends of the tube for a moment then gives it a high voltage spike to start it without flickering.

The ballast has a rectifier and filter for the mains then a 40kHz stepup inverter. A current-limiting capacitor feeds the tube.

"700mA from a 6V battery is only 4.2W. The inverter is about 80% efficient so the 9W bulb gets only 3.36W. That would be quite dim."

[pier]

this is the ckt i told u , i saw .

[pier]

i'm sorry for that space

[audioguru]

It is a huge paper with a tiny schematic on it.
Make it, measure its current and see how dim or bright it is.
Are you going to take it camping? The bears might eat it. ;D

[pier]

i already measured its current . as i said earlier it draws only 700 mA from a 6 volt battery . and the brightness is very good and sufficient . but i dont know the transformer details . thats the problem . i know all the other values .

[audioguru]

I have never seen a transformer with an extra winding like that. It must be custom-made for the light.

[pier]

since it self oscillating it must be the one for oscillating , some say that it is a feedback winding .

[audioguru]

since it self oscillating it must be the one for oscillating , some say that it is a feedback winding .

It is a feedback winding. Your schematic shows it shorted, and a resistor is missing for one of the transistors.

[pier]

u are right . I made a mistake by missing one resistors .

Do u have any Idea about the winding details Or could i get a new one for that

Pier

[audioguru]

Do u have any Idea about the winding details

Every transformer is different. The number of turns for a feedback winding is a ratio with the existing number of turns in the low voltage winding. You don't know how many turns are in the existng winding.

There are lots of ways to make an oscillator without using an extra transformer winding.

[pier]

the low voltage winding is 8 - 0 - 8 and 0 is battery +ve

[audioguru]

Where are you going to buy an 8V-0-8V transfomer that has an extra feedback winding?
If the turns on the extra winging are not enough then the inverter won't start, If the turns are too many then the transistors will blow up.

[mvs sarma]

you may use 555 as oscillator and use one driver transistor like C1061 and use 6V/230V transformer [ if possible the core shall be repacked (All Es one side and all I s other side ], with a gaping paper placed between them and the whole Transformer repacked) to prevent saturation-- for oscillator you can also try cd4047b both in astable mode at say 40KHz. of course the component count will be more as compared to what you showed. Finally the CFL will not have filament drive and the CFL itself needs a modifivation in the sense that these CFLs come with a built in starters meant to work at 230v/115v AC with a suitable choke. this starter is to be replaced by acombination of 470K(0.25 W ) resister and 2n2  cap in parallel.

many chinese make lanterns use HiTachi type 6" tube without filament pre-heating

finally perhaps audioguru 's openion is right that the illumination may not be to the expectation??

you may however try it out

sarma