Joule Thief

[crowclaw]

@crowclaw:
I have several working joule thief circuits, and have learned a lot.  My desire is to run a Newman motor that I am building.  I will need help in designing a JTC to deliver around 1000v.  If you have not seen my videos yet here is a link to one:
http://www.youtube.com/watch?v=F6qLiAeyPng

I am willing to use, say a 12v source.  I just need to know what is a proper transistor to deliver 1000v.  I have used a disposable camera's flash transformer to get up to 350v from a AA battery.  Technically, I am not concerned about how much current there is.  In a Newman motor, it is desired to keep the current as low as possible and the voltage high.  Though the coil in the video link above is only about 50ohms, and that would try to pull way to much current from my current JTC setup.  I have come across some bigger transformers, and want to use them.  So the question is, what components (transistor mainly) do I need to go from 12v to what ever I can get out of one of these transformers I have? 

Thanks for your input Crowclaw, it has me thinking.

Hi detrix

OK You'll need a transistor that is well suited for high voltage pulse use, so go for one of the old TV scan output devices, many of these can cope with over 1200 volts VCE. There are many scrap TVs around since plasma and LCD sets have come along so take a look in disposal sights for an old set, older the better. The types you are after are BU208 or BU508 the "D" versions have an integral diode. Also older sets have usefull ferrite transformers to wind your coils with, or the line scan output transformer from a scrap TV could also be used. You will have to experiment with your base resistor value and I would use say 22R in series with a 1K pott for the base bias to "tune up" your circuit. Don't use laminated power type transformers as they tend to be OK for lower frequencies, you need to get fairly high frequency pulses. Be prepared to experiment to find the right voltage levels... you shouldn't have any problems otherwise; and with the right transformer the current draw should be within your spec. Let us know how you progress. Kind Regards

[crowclaw]

@ detrix,

The transistor types I have mentioned are just two fairly common devices, however there are many others that will be suitable for your project with similar spec's. Regards

[forest]

It should be possible to have JT generated 3kV from 4.5V input. I state that because I have now in my hand disassembled circuit from small ozone generator.Unfortunately it's all covered by epoxy resin :-(

[detrix42]

Ok, I am in the process of removing the flyback transformer from a 32" american television. Due to the high voltage that this thing can generate, I would like someone from this tread to walk me through steps to hook up a joule thief output to this flyback transformer.  I only want about 1000v for now.  I am trying to look up the pinout but I am not gettng anything from google with the part numbers I am seeing.  (TFL2AA002 from a panasonic tv).

[forest]

Ok, I am in the process of removing the flyback transformer from a 32" american television. Due to the high voltage that this thing can generate, I would like someone from this tread to walk me through steps to hook up a joule thief output to this flyback transformer.  I only want about 1000v for now.  I am trying to look up the pinout but I am not gettng anything from google with the part numbers I am seeing.  (TFL2AA002 from a panasonic tv).

Hmm..that would be hard task because TV flyback likes to generate much more then 1000v