Joule Thief

[SkyWatcher123]

Oh and I just put a 6 turn base and 12 turn collector JT on the 1" diameter toroid shown with the tape on it, 26awg. and it works very well, easily lights 8 leds to full brightness I would say, because it is painful to look at. My amp meter shows 180 milliamps at 1.25 volts AA nimh. I intend to wind a 30 gauge secondary and see what it can power, maybe a fuoro, i hope.
peace love light
Tyson

[conradelektro]

@ Gary (resonanceman):

Thank you for explaining your air coil ideas. It looks really simple to build and I guess that such a coil works well for a "low voltage" Joule Thief (just a few LEDs over collector - emitter with no secondary, or only a few LEDs on a secondary).


In order to get high voltage from a Joule Thief (1000 Volts and more) one needs a BIG AIR COIL according to my experiments.

By BIG I mean at least 75 mm diameter and very high like 360 mm (about 1000 turns of thin wire for the secondary),

or 250 mm diameter and 100 mm high (250 turns of thin wire for the secondary).

The bifilar primary (wound over one end of the secondary) should have about 15 turns. And it is also o.k. to wind the two primaries apart as two separate coils. It had little influence to use a different number of turns for the primaries (if one uses a huge secondary). Too few windings for the bifilar primary are as bad as too many. I plan to go into a pancake type primary in my next experiments.


If one wants high voltage from a JT a good toroid (at least 40 mm diameter) is a simple and space saving solution. And I saw that people used fly back transformers with success. If one goes into air coils and high voltage a lot of space is necessary.

But for low voltage JTs without a secondary (only a few LEDs) one can wind very small and crude air coils like Gary does. Just wind 40 turns bifilar over your finger (can have multiple layers), fix this thing with tape and you have a coil for a JT. I think it was Gary who showed that even a tangle of wire also works or a twisted pair of wires.

As I said so often, air coils allow high frequency in a Joule Thief (1 MHz and more) and this is why I am so interested in them.

Greetings, Conrad

[Artic_Knight]

@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

jenna actually i started with a choke. it works but very poorly. in short your milliamps will be much higher then with a good ferrite but it works

[Artic_Knight]

@ All,    I know this is a little off topic here but if I had a solar panel producing very low volts
            at high Amps 10+,  would  normal thin insulated wire work ?

be careful with large amps and small wire, it can over heat the wire and burn it out. but considering your at a low voltage it might be ok depending on the diameter of the wire.

power companies step up the voltage for 2 reasons 1) high voltage low amps travels better with fewer losses over long distances  2) smaller wires can be used with less amperage traveling over the wires thus saving on costs of materials

[Artic_Knight]

Thanks,  just one more question... I will be getting a small digital panelmeter that measures 0-20v,
                 Now if I have a solar panel that puts out 3v at 8-20 Amps, would the meter be alright with
                 Amps like that ?

reading volts it should be fine but if its also a amp meter make sure you do not exceed the rated amps for reading. otherwise you will either blow a fuse or fry the meter.

when the volt meter is set to read volts it does not pass amps through it. however when its set to read amps it has to be placed into the circuit IE power goes through it and thats when you risk blowing it. of course if its rated for 20 volts and you send a 1kv surge through it that could fry it too