Joule Thief

[timmy1729]

Thanks  . That is good for my lacking ego . Again another accidental find . I just happened to be trying Various diodes and caps on different spots  and saw the leds get brighter and the current draw go WAY down.and Soldered that sucker . I tried Various caps last night and the optimum for this coil is 680pf or 68 pf . what i tried was more windings . it detuned and raised the current draw light went dim  . i took more winding off . same thing except the current went up and the lights got brighter than bright . i did not have enuff adjustment on my pot to see if i could decrease the current and have full lit leds. i tried adding a secondary with 5 or 6 windings ,nothing on the output . and no further current draw either . so i will try winding a large secondary past the 80 windings with smaller wire and see if i can get anything off the secondary and without increasing the current draw . Also i am using an germanium Transistor . I will try a Silicon transistor today and see what happens.. Oh one more thing . the c2 on my circuit is across the battery . i removed it and the current draw went up and the light got dimmer . So with the elecro cap across the battery the current draw decreased by .20 ma and the light s got brighter . the reason i can see a different in light is i was running 4 leds at 1.15 ma total and the slightest difference is seen.In My circuit it is needed .

What is pF in relation to uF? All of my caps are uF.

[xee2]

@ timmy1729 

What is pF in relation to uF? All of my caps are uF.

Converter here:

http://www.unitconversion.org/electrostatic-capacitance/picofarads-to-microfarads-conversion.html

[gadgetmall]

I got it Lower . i wound a Smaller torroid that everyone else uses the about 1 inch one and i wound serial 100 turns center tapped . then on the rest of it i wound 30 turns secondary.. well i am running 4 leds now with less than 1 ma . i can go lower than that which is full bright . but i need to find another resistor because i am bottomed out at 1 ma  same dead battery much brighter off the secondary with the cap on the var resistor  :thats 1 ma /4 =  0.25ma each ...still experimenting with germanium though . batt at .88.edit ok i got it as low as it can go . i can adjust to.43 ma and still see all 4 lights . here is .81 ma lit good !!! i added another 20k pot and 680pf to the new coil above circuit.thats 0.20 ma per led . Hows that for improvment . I can now run these leds for a Very Very Very  long time ..Off of dead batteries

[timmy1729]

@All

This is for all of you junk fanatics!
I remembered I had this old pc from around 1990 that I got from an old job and that I should be able to find some toroids in that power supply as well. I opened it up and let me tell you, this thing is a gold mine!

I counted six visible toroids of various sizes and windings! There are many different transformers of various sizes and a whole variety pack of caps! There are a couple of 200v 560uF caps on there and two 6.3v 6800uF caps and two 16v 3900 uF caps! Woohoo! 

One of the board in the pc had about four or five 2n3904 transistors on it! There are more resistors and diodes on this power supply than I could've imagined! It is a beautiful thing!

The point: With the two pc power supplies I've taken apart, the older it is the more cool parts you can find 
So, if you are looking for a good source of cheap parts, get an old pc at the flea market or junk yard and save yourself a LOT of money and save the planet at the same time    I will post some pics of the two halves of the power supply before I start taking parts from it. It's just a beautiful sight!

Can someone tell me how to test these transformers to see if they are 1:1 or are step-up/down and by how much?

Also, I need a little clarification on something. When I have a cap across the + and - of my LED(just for example), what matters more, the uF or the voltage? like above, I have 200v 560uF or 6.3v 6800uF. What would make my LED brighter, in theory? Caps still confuse me to no end. Does the voltage rating just say that it will output the current at that specific voltage and the uF just say how much current the cap can hold at that voltage? Can it hold current at a lower voltage and output it at that lower voltage? Or does it always output at that rated voltage? Can they hold more current at a lower voltage than it is rated for?

[Mk1]

@all

I just got 5 more 7w led to play with!