Joule Thief

[jeanna]

  @ Jeanna,  I am waiting on a heap of superbright 5mm LED's from overseas, Is it possible to light say
                     12-18 LED's in series with 7-10 spiky volts per LED with a total current draw from a
                     JT of 5-25 mA's  and all LED's lit fully bright ?

                     

I don't think I have done that.
My circuit with multiple secondaries used 245mA when it lit 30 or 32 leds to full brightness.
With series inductors and maybe a cap in the right amount and in the right place, maybe you can.

Parallel is a different story.
I made a very bright light with 6 parallel strings of 7 leds that were in series for 42 leds. I don't think they were fully bright and 4 strings would have sufficed. (I think 4 strings would give the same total brightness.)
The experiment was also to see if the frequency seemed to hurt the leds.
I believe it did NOT.

Anyway, to answer your question:
If you have a 25mA circuit that produces 120-180 spiky volts, the answer should be yes.
Be sure you have a very high permeability toroid, or this won't work.
Maybe a higher value series inductor will do it. I love this idea... please try it.

@Artic Knight
NOT a choke... OK?
The joule thief uses a high permeability toroid. the highest permeability you can find.
Type W is what you want.
I wasted $35 on a minimum order of chokes that wouldn't even turn the circuit on.
Maybe this can save you some trouble.

thank you,

jeanna

[freepow]

@ Jeanna, What do you mean when you say... Maybe a higher value series inductor will do it.



@ All...   Does anyone here know if say you had a   2.7v 650F CAP, and you charged it up with mA's or Amps
             at only  1v, would the CAP still charge to its full capacity of Amps ,even though you only
             charged it to 1volt instead of 2.7v ?

[teslaalset]

@ All...   Does anyone here know if say you had a   2.7v 650F CAP, and you charged it up with mA's or Amps
             at only  1v, would the CAP still charge to its full capacity of Amps ,even though you only
             charged it to 1volt instead of 2.7v ?

For a capacitor the following formula holds:

Q=C*U

Capacity C is given.
So, if you charge it up to 1 V, Q (charge) will be 1/2.7 of the maximum charge it can hold.
Charge (Q) en current (I) relate as:

I = Q/t or Q = I * t

In other words:

I * t = C * U

You can draw the conclusions.

[freepow]

   To any one who may know the answer to this...
 
      Say I have a large Cap rated at  2.5v @ 55 F,  and I charge it at say  2.5v with so many mA's or Amps,
      Can I connect a meter to the Cap while charging and look at the meter to show the Cap charging up
     
      With the meter reading on Volts,  would I be able to tell when the Cap is fully charged by the meter

[jeanna]

@ Jeanna, What do you mean when you say... Maybe a higher value series inductor will do it.

Hi freepow,
I meant more henries.

@ All...   Does anyone here know if say you had a   2.7v 650F CAP, and you charged it up with mA's or Amps
             at only  1v, would the CAP still charge to its full capacity of Amps ,even though you only
             charged it to 1volt instead of 2.7v ?

I am pretty sure the amps will be in a kind of proportion and not full charge until you have 2.7volts.
As the charge fills the "plates" of the cap the voltage builds, so the charge (or the stuff that makes amps) will come first and it fills both elements together.

The exception is the voltage spikes.
They do something different, as always!

jeanna