Joule Thief

[Pirate88179]

@All
I was wondering if we could get more power out of a Darlington transistor setup, using Power Transistors.
http://en.wikipedia.org/wiki/Darlington_transistor
One reason for using the smaller transistors is they have a higher hFE factor then power transistors.
But the Darlington setup will take care of this. 

What transistors can we use to make up this pair?  Would we benefit any from making up the other pair mentioned in the link you posted?  (PNP and NPN)  As xee2 suggested, it would not be too hard to replace our little transistor on the Fuji board with something else a little more robust (and heat sinkable) and whilre we are doing that, maybe we should try the Darlington Pair approach as well?  I can see it now.  I need a bunch more of the AA boards.

@ All:

Since there is really not much left on my Fuji board as far as components go, would it not be possible and probably better to just copy the transformer, transistors, etc and rebuild on a proto board?  This would make it easier to test different transistors including the above mentioned Darlington Pair configuration.  I would have to figure which pins are being used on the little transformer and how to hook it up but, once we did this, we could find the most efficient combination and then really see what it can do.  If we found a set-up we liked that worked well, it would not be hard to make our own pc board for a permanent device since there are only a few components.  What do you guys think?

Bill                                    Happy New Year!!!!!!!!!!!

[Pirate88179]

Here is the visual difference from the outside of the camera. THE BOX IS THE SAME FOR BOTH!. I moved---sorry for the fuzz.

The AA has a push button and is a smooth rubberish button you hold for 1 flash or lift up the door for continuous flash.
The AAA has a green button with 4 bumps that you slide up into position for flash.

I hope this uploads.

jeanna

Wow, I had to go back about 12 pages to find Jeanna's post.  I wanted to repost this because it is important for those of us that are going out to seek "FREE" Fuji's from the photo places.  If they say we can look through their barrel, or if they have a bunch and ask which ones we want, Jeanna has come up with a quick way of identifying what is inside by looking at the push button.  I think this is important enough to repost here now that I went back to find it.

Thank you Jeanna, this will save a lot of us a lot of frustration from bringing home the "wrong" cameras.

Bill

[xee2]

@ Pirate88179 

I only ran Fuji AA board for 5 seconds at a time with 3 volts because I was afraid the transistor might melt if I ran any longer. To use 3 volts I think that the 220 ohm resistor will need to be increased and the transistor will have to have a heat sink. But if seems like the transformer can handle the higher voltage (that is what I was checking).

It certainly would be easier to experiment on a proto-board. The only thing I think you need from the camera is the transformer. I think freezer's transformer pins may not be correct for the Fuji AA boards I am using. If you remove the transformer from the board you will need to confirm the pin out.

[Pirate88179]

@ xee2:

Yes, I agree with you.  Also, I believe that with a little searching, we can find an OEM supplier of these transformers and probably buy a bag of them for maybe $5.00. 

Yes, I remember what you said about the 5 seconds.  I didn't mean to imply that one could just pop 3 volts into the board and it will be ok. (I hope no one tried that based upon my comment)  I do remember you saying that the transformer seemed ok with it.  Also, we need a transistor (or pair) that can handle 6 watts or so correct?

I am looking around online for a full size proto board.  I only have a 3 x 5 inch one.  I can most likely find a cheap one somewhere.  I am not sure about that metal cased capacitor as far as its value.  Mine does not have any readable markings on it.  That is the only thing, other than the transformer,  I may have to use from the board until we can figure out what it is.  Thanks.

Bill

[WilbyInebriated]

yup bill, they light both ways cause it's ac. so you should be able to reverse the polarity on half your led strings to get the most out of what is coming out of the circuit.