Joule Thief

[brownsville]

Hi all,

I have been away for over a month and have a lot of catching up to do.

I took apart an old scanner / copier / fax machine about a month and a half ago and found that there is a long thin fluorescent tube and a circuit running the tube it works on 12 volt and mili amps. Have not had time to get it working but thought someone else here could take a look at one..They seem to be readily available for free. Sorry I don't have more time to send pictures that I took of the circuit. There appear to be a couple of 2n222 timers and a few capacitors and a high voltage coil that light up the tube.

Hi Bill.

Brownsville 

[jeanna]

@Brownsville,
Hi... welcome,

Wilby (aka wilbeinebriated, I think the sp?) lit one of those and made it into a funny joke with a beer jug. He called it a beer lite or something... If you missed that, go hunt it down. He gave specs.

Hi again, thanks everone for your response, its great to talk to people with same interests !
Well this toroid that i'm using on this circuit now is a 1.5 inch diameter ferrite bought from jaycar electronic in Aust

Excellent. This is great because once you get it right you can get another!

, and hand wound with 2 wires, each wire of 20 turns together (bifilar),

So, 40 turns? That is a lot of turns.
But since it did well, it may be what you need, so hold that thought.

I have one 14-16,000 mcd LED, it light very brightly with DC on this toroid at about 113v, when I connect double volts = 3v, I get about 240-256v on multi-meter,

I do not believe this is that many volts, because you can't do that to a led. They burn up at too many volts, and we have been blasting ours not by burning but by high volts high frequency. They get bright for one moment then nothing.

What does it mean "double=3v"?[EDIT:
Are you saying you use 3v input and get 240v output?
Something is seriously wrong with this.
The input voltage is there only to make the transistor work. I have never found much of an increase with the addition of a second battery. end edit]

can you get a neon from your electronics store?
It will light at the voltages you are reporting and then you will know.

so I went down to 4 turns with 2 wires, that = about 30-40v, ...
in that 60t, else it would be bright, so, dont honestly know whats wrong.
...
But the only thing i cannot seem to get past - is getting decent high volts of AC !

How do you know what the volts are?
They do NOT show up properly on a dmm.
The regular dc volts in the regular dc circuit is all you can read from a dmm.

I think you should be getting 60 volts with 4T4T60T set up but that will also depend on the value of the resistor at the base.(AND the kind of toroid, AND the transistor)
Have you ever told us what that resistor value is?
1k is where to start. Some toroids will work with a higher resistor but just go down from 1k for the start.
I have many toroids that like 245ohm as well as 35ohm, so there are 2 spots, but I learned this from a scope.
MK1 uses a potentiometer and rectifies the output from the pickup through a rectifier . Each end of the rectifier output is run further through another diode because the high frequency maybe ignores the diodes sometimes, and then he collects it in a big cap- the kind of cap you find in a disposable circuit.
The dmm can accurately tell you what the cap collected. Put it on HV for safety.
Is this how you are getting the ac output information that you are reporting?

There is no question about it, you must fiddle with all the pieces. But once you get it right, you can repeat the results in each room. This is my idea. I have used one led in each room for many years, but they are not bright enough in the normal circuit. These leds from the pickup are great. Not because one is brighter, but because you can light 15 of them.

I am not sure how to help. You just have to keep fiddling with different numbers of turns and resistance for each toroid and transistor you use.

sorry, I can't help better,

jeanna

[Mk1]

@freepow

Welcome, just make sure that every time you change anything on your jt ,you adjust the base resistor , usually toroid work better at some freq , so to make sure you improve things and not test blindly , use a pot at the base of the jt and always rectify and note the best value , once you get over 100 volts , you should be able to read the secondary (pickup coil) with out diodes on the ac set up .


2n3055 and 2n2222 works on my tube not 3904 .

Mark

[dllabarre]

@Jeanna, Bill, anyone

What was that website where you buy your toroids from?
I thought I saved the URL but can't find it now.

Thanks,
DonL

[jeanna]

What was that website where you buy your toroids from?
DonL

I got the tor-23 and the biggo and I am now testing the tor-61 from
http://www.allelectronics.com/
I got the filter which has made awesome MK1 setups
and the med 5/$1 which I find very mediocre from
http://www.goldmine-elec.com/
The filter is in the inductors section and has 1.39mH per side 2 sides already wound and you can save them or play with part of it or take it off.

jeanna