Joule Thief

[Artic_Knight]

This circuit lights fluorescent tube using only one wire. Not very bright but seems brighter than Fuji board and it is using less current than Fuji board.

i will bet if you ground that wire in the earth the one left hanging it will work better   all it takes is a nail.

[jeanna]

@xee,

I have some 47uF caps. If I put them in parallel in the battery rail won't I get the same thing you have in your 100uF in your battery rail? (less a few, obviously)
I also have a few of those fuji caps. Is that what you are using in your battery rail?

I only have a 7 watt fluoro tube (and larger) and my secondary is not as high a multiplication as yours, so I doubt if I can achieve this today, but since I am getting 260 to 370 v as shown on the scope, I thought I should be getting close.


Yesterday before I managed to get the string o leds to light I tried several times to light the fluoro tube, and it kept getting a hot spot just to the side of middle of the tube. This makes me think I am getting close to a light. I want to push it more today.
---
I have another question for you.

The other day you said something that made me think you were saying the amps draw from the battery couldn't come out through the secondary. I don't see why not. Do you remember what you were saying? I can find it if you don't. I have been mulling this over for a few days and now the quote is buried.

Is that the reason you are connecting directly to the pos on this?

thank you,

jeanna

[jeanna]

@xee
Here is that statement you made:

from: jeanna on May 17, 2009, 11:30:01 AM

    As I understand this to call a lightbulb 4 watts means that at 120 volts it draws 33.4mA and so V x A= W therefore 4 watts.

Yes. But it will only be 4 watts if both 120 volts and 33 ma are available. If 120 volts is available but only 10 ma is available, then the tube will only be using 120 X 0.01 = 1.2 watts. In the JT the output can have 120 volts but not also 30 ma and so it can not light the tube to its full brightness.

Actually, in the JT we are not using the tube the same as if it were in a light fixture. We are using it more like a neon tube.

In the battery many more than 33mA are available.
Why, if they can be drawn from the battery to do some work, can they not be drawn to do some more?

thanks,

jeanna

[xee2]

@ jeanna

I have some 47uF caps. If I put them in parallel in the battery rail won't I get the same thing you have in your 100uF in your battery rail? (less a few, obviously)
I also have a few of those fuji caps. Is that what you are using in your battery rail?

Yes two 47 uF in paralle is 94 uF. But the battery cap value us not very important since it has little effect on circuit. I am just using what I had handy. Fuji caps will work.

I am getting 260 to 370 v as shown on the scope, I thought I should be getting close.

It takes about 400 volts to light the 4 watt tube. I suggest you test your circuits using the neon until you are able to get 400 volts.

I have another question for you.

The other day you said something that made me think you were saying the amps draw from the battery couldn't come out through the secondary. I don't see why not. Do you remember what you were saying? I can find it if you don't. I have been mulling this over for a few days and now the quote is buried.

Is that the reason you are connecting directly to the pos on this?

No. I meant that when the battery energy is tranformed to a higher voltage at the same time (or as a result) the current is reduced. Look at basic transformer theory.

[xee2]

@jeanna

An AA battery is able to produce about 1 watt of energy. Watts = amps x volts. So if you had a 100% efficient converter you could convert the 1 watt from the battery into 1000 volts @ 1 ma, or convert it into 10 amps @ 0.1 volts, or any combination of amps and volts that equals 1 watt. The JT is a voltage converter.

The watts coming from the secondary can not exceed the watts coming from the battery. So if the battery is producing 50 ma at 1.0 volt then it is producing 0.05 watts and therefore the pickup coil can not deliver more than 0.05 watts. That 0.05 watts can be any combination of amps and volts as long as the product is less than 0.05 watts.