Joule Thief

[jeanna]

I've been away recently.

I apologize for the brevity in this post, but I'm looking for a JTC style circuit which produces AC in as clean a way as possible.  This means it should utilize two paths, or a center tapped transformer, this won't be a problem ...

Any suggestions would be appreciated.

- - - - - - - - -

On a side note, I recently pulled the driving board for a scanner bulb out along with the bulb itself - low an behold, it was a joule thief style circuit.

Hi Jadaro,
I assume by aC, you are meaning something that would light a neon on both sides?

The best examples of this that I have found are the MK1 designs type of secondary
these are the kind that have the secondary wire going from one central point and winding to the left,
then returning to center
then winding more to the right
and returning to center.

You do not need to make very many turns to try this out. All the ones that got posted were very many turns, but just some work that way too.

Interesting about the scanner.
It seems this is a widely used circuit.
(Go stubblefield!  )

jeanna

[dasimpson]

would you please try this with a bc337-25 as these are what i am using and i could not get a single wind secoundry to light a led
only the foule thief primery led works i havent as of yet added winds till i get an led to light thank you

dave

just an update i rewound a toroid black and it is 250mm 7mm 3mm i folded a single peace of cat5 cable and wound it round the toriod 10 times 20 turns in total draws 50ma from a full battery i have used a 1k resister and a bc337-25 and with one turn i light the led with 3 turns the led is at full brightness

@MK1

I just exchanged the 2222 that I have for the 3904 I have been using in my breadboard experiments. I may not matter, but just to be clear, the toroid in this is the half wound one with the 1 1/2 turn secondary.

The 2222 draws .44A from the same exact set up where the 3904 draws only 0.33A
So, the lights look about the same brightness, but the amp draw is higher with the 2222.

=======
May I get an explanation please?
About counting the turns. If I start at the outside of the toroid and feed both ends through the middle and end where I started, is that 2 turns? It seems one turn to me one complete turn. There are however 2 strands of wire going through the center to get there.
Ist used a way to close the wire by twisting it onto itself and so close it. Is that one turn?

Thank you,

jeanna

@MrMag    thanks. I will see if that helps. thanks for trying.

[jadaro2600]

jadaro:

Welcome back.

What do you mean by "clean" exactly?  A single frequency as opposed to multiple frequencies?  A good solid sine wave?

I am just curious.

Bill

Yes, something with a good sine wave ( with very little DC bias ).  Something that would light a neon on both sides.

[jeanna]

would you please try this with a bc337-25 as these are what i am using and i could not get a single wind secoundry to light a led
only the foule thief primery led works i havent as of yet added winds till i get an led to light thank you

dave

just an update i rewound a toroid black and it is 250mm 7mm 3mm i folded a single peace of cat5 cable and wound it round the toroid 10 times 20 turns in total draws 50ma from a full battery i have used a 1k resister and a bc337-25 and with one turn i light the led with 3 turns the led is at full brightness

Good job!!!

Hi Dave and welcome,

I assume you are trying to catch up since this quote is from last year.
I have learned almost everything I know SINCE then! 

Not getting a single secondary wind isn't a big deal. It astonished anybody that this would work and has a lot to do with the permeability of the toroid.
Usually, I recommend that people turn as many winds as make a nice bright light then multiply that number of turns by the number of leds they want to light and wind those turns onto the toroid.

Sometimes you can run out of room in the center and so must limit the leds.
Sometimes you 'choke' the primary with too many turns and need to back off some, but mostly,  it is a pretty reliable way to arrive at the number of turns you need.

And, please remember to remove the led from the C-E junction when you are using the secondary. when the led is in that C-E spot, then IT is the thief.

As for the high amps draw, it could be the transistor.
Now that you have successfully made the secondary light turn on, it is time to tune the primary.
To do that, begin by removing one turn at a time from the collector coil, checking for brightness and stop when the light gets dimmer and add back that last tuen then remove turns from the base side.
the collector side of the toroid does best when it has the higher number of turns so expect to take off more from the wire that touches the base resistor than the collector.

Later on last year we decided to name things and agreed on some conventions.
They are all collected in the joule thief 101 thread, I think.

Have fun,

jeanna

[dasimpson]

ty that has really helped clear alot up for me i got to 5 winds and damn got to remeber not to look stirght on at the bloody led so do you thin tuning the collecter and base winds will drop the amps used also when you said add the same winds per led is that led's in parallel or series
i was thinking of keep each 5 winds per led separate

Good job!!!

Hi Dave and welcome,

I assume you are trying to catch up since this quote is from last year.
I have learned almost everything I know SINCE then! 

Not getting a single secondary wind isn't a big deal. It astonished anybody that this would work and has a lot to do with the permeability of the toroid.
Usually, I recommend that people turn as many winds as make a nice bright light then A that number of turns by the number of leds they want to light and wind those turns onto the toroid.

Sometimes you can run out of room in the center and so must limit the leds.
Sometimes you 'choke' the primary with too many turns and need to back off some, but mostly,  it is a pretty reliable way to arrive at the number of turns you need.

And, please remember to remove the A from the C-E junction when you are using the secondary. when the led is in that C-E spot, then IT is the thief.

As for the high amps draw, it could be the transistor.
Now that you have successfully made the secondary light turn on, it is time to tune the primary.
To do that, begin by removing one turn at a time from the collector coil, checking for brightness and stop when the light gets dimmer and add back that last tuen then remove turns from the base side.
the collector side of the toroid does best when it has the higher number of turns so expect to take off more from the wire that touches the base resistor than the collector.

Later on last year we decided to name things and agreed on some conventions.
They are all collected in the joule thief 101 thread, I think.

Have fun,

jeanna