Joule Thief

[tinman]

Speaking about JTs,here is my cool joule working with no magnetic coupling between the trigger and driven coils.
Bit of a brain teaser for you all.-from 2.20 onward.And yes,that is heavy rain your hearing in the background.


http://www.youtube.com/watch?v=z7DlD8MIEes

And a replication from Jouleseeker
http://www.youtube.com/watch?v=UPHfqQFCNtw

[TinselKoala]

Hi Luca

I've redrawn your battery charger schematic to go into my notebook. I use this "rail-to-rail" format because it's easier for me to see what's going on this way. Please check and see if I've made any errors.

Have you tried just using a single, center-tapped winding on the toroid, with the same number of total turns as your six-filar winding? It would be great to have two toroids, one with the six-filar winding like you've got, and one with just one continuous wind, center-tapped, like I put in the schematic, for comparison.

[TinselKoala]

Speaking about JTs,here is my cool joule working with no magnetic coupling between the trigger and driven coils.
Bit of a brain teaser for you all.-from 2.20 onward.And yes,that is heavy rain your hearing in the background.


http://www.youtube.com/watch?v=z7DlD8MIEes

And a replication from Jouleseeker
http://www.youtube.com/watch?v=UPHfqQFCNtw

Nice demo. The fact that the signal doesn't change much when you put the trigger coil into the field of the stator magnets is telling me something: the coil seems to be acting more like a resistor, not an inductor.

Have you tried this:

Calculate the AC impedance of the trigger coil at the frequency you read on the scope when the thing is oscillating. Now just substitute in a carbon or metal film resistor of the same DC resistance as your calculated impedance, instead of the coil. You will probably have to "tickle" the system to get it to oscillate, probably, by briefly shorting base and emitter or base and collector with a quick swipe of a bit of wire. Can you get it to oscillate at all when you do this?

That is some little rain shower you've got going there! Sounds like a typical Texas summer thunderstorm, what we call a "gully washer" or "frog choker" here, but without the thunder. Good thing your lab is nice and cozy and dry.

[tinman]

Nice demo. The fact that the signal doesn't change much when you put the trigger coil into the field of the stator magnets is telling me something: the coil seems to be acting more like a resistor, not an inductor.

Have you tried this:

Calculate the AC impedance of the trigger coil at the frequency you read on the scope when the thing is oscillating. Now just substitute in a carbon or metal film resistor of the same DC resistance as your calculated impedance, instead of the coil. You will probably have to "tickle" the system to get it to oscillate, probably, by briefly shorting base and emitter or base and collector with a quick swipe of a bit of wire. Can you get it to oscillate at all when you do this?

That is some little rain shower you've got going there! Sounds like a typical Texas summer thunderstorm, what we call a "gully washer" or "frog choker" here, but without the thunder. Good thing your lab is nice and cozy and dry.

No,couldnt ever get it to work with a resistor inplace of the coil,but a lot of us got it to work quite well useing those little resister looking inductors.
Seems like it was the small amount of capacitance within the transistor that allows it to work with the uncoupled coils-inductors.

[gnino]

Hi i try this toroid and fail