Joule Thief

[dasimpson]

i got upto 7 leds but every time i add one the other dimm slightly they ran for about 4 or 5 hours my current draw is anyware from 20 to 100 ma i think im going to stop untill i get some 2n3904 as i see ppl have had some really good results
if i wonted to run the led's in parrallel would i need less turns or would running them in series be best i really dont have a clue i keep trying but to no avail

[dasimpson]

would apper on a fully charged aaa 600mah bettery my joule thief pulls 120ma

[resonanceman]

if i wonted to run the led's in parrallel would i need less turns or would running them in series be best i really dont have a clue i keep trying but to no avail

dasimpson

Series or parallel  depends on the JT.
It you have plenty of  voltage but not much current   series works  best. ........  if you have low voltage  but plenty of power parallel works best ........ If  you have  plenty of power and  voltage   you can do  a few parallel and a few in series.......



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have you tried  using less turns  on your primary?
Some toroids need  around 10  turns........but if  you can  get by with less........ you will need less turns in the secondary  to get the same voltage........


gary 

[dasimpson]

i use 10 bifilar for the primiery and about 5 turns for every led secondry but i find each time i do that the other led get a little dimmer i am at moment out of enamel wire going to strip a hobby motor in a bit i wont to light 22 leds so by what i have read that sound be a 110 turn secondry but what i dont know what to do is if the 110 choke the oscerlation how to cure that and keep all led at full brightness

the parts i use are 1k resister bc337 transister untill i can get some 2n3904's a 1 inch black toroid and cat 5 wire

dasimpson

Series or parallel  depends on the JT.
It you have A of  voltage but not much current   series works  best. ........  if you have low voltage  but plenty of power parallel works best ........ If  you have  plenty of power and  voltage   you can do  a few parallel and a few in series.......



`````````````````````````````

have you tried  using less turns  on your primary?
Some toroids need  around 10  turns........but if  you can  get by with less........ you will need less turns in the secondary  to get the same voltage........


gary

[jeanna]

Hi dasimpson,
Gary is correct about the series and parallel.
It really makes little difference.

I have 2 lamps made in this simple way we are discussing. One has 24 leds with 6 in series but 4 strings of them, and the other has 42 leds with 6 in series again, but 7 strings of them. They are both bright and both last a long time with one NiMH AA that has 2500mAH. If you are using a 600mAH battery, you are doing really well if you get more than 8 hours, especially with that transistor.

Also,
You do not want to kill your rechargeables by taking the voltage too low over and over.

I also want to mention that my best tuning for one of my toroids is 2Turns on the base and 9 Turns on the collector.
another is 5T on the base, and 8T on the collector.
If you are using the 5/$1 kind from goldmine, I think the best tuning is 6T,6T even, but I am not exactly sure there.
The point is there is a wide range and do not be afraid to get really off balanced.

When you have 2 secondaries, one often goes out, so maybe concentrate on using just one secondary. You can get the 2 to both light the leds but you need an extra inductor in series... more fiddling!

It is great to see you doing this so well and so quickly.

jeanna