Joule Thief

[jeanna]

Ist,
How do you blow up a coil?
What happened?

jeanna

[innovation_station]

im guessing because my wire was so fine ...  it found a week point and melted it  im not sure i have to inspect the wire ... lol

ist


maybe the uni ....  is telling me not to use the bridge lol 

what ya all think 

[Mr_Video]

@ ist

looks like you're just one step away from creating the world's smallest Tesla coil   LOL

how much current does that thing draw ?

maybe TOO much current, if it blew out your coil .

nice work though !

[sm0ky2]

Hi Sm0key2,

You must have an oscillation that starts and stops the coils. Without that, all you will get is the action of a single battery.

It is not the amplification of the transistor you are after, it is the switching.
So, knowing that it is working is great, but now, can you see it turn off?
I suspect it is fully on and not turning off ever.

Have you watched how Bre Petis connects the wires yet? [makezine video]
http://www.youtube.com/watch?v=gTAqGKt64WM
That is the first step in my suggestions.

keep on trying...

jeanna

you are probably right, it may very well NOT be turning off, theres a constant current flow through the base resistor, which tells me it should be always on. though i have no way of knowing for sure. if it is switching, its happening so fast i have no way to detect it without a scope.

So, the question now is. how to make it switch off?

[jeanna]

Hi Sm0key2,
That is the purpose of the 1k ohm resistor.
I am glad you can verify that it is indeed on all the time.

I guess if you didn't blow the transistor,  because you have the same trouble with several of them, it is in the way it is wound or the core.

You have not told us what the core is, if you know. You probably know where it came from. We have dump experts here who might be able to tell you what it is from where you got it.

The most likely thing is that the wires are not center-tapped.
It is the center tap that makes it turn on and off with a great deal of leeway.
So, they can be connected in a series way, if you want to call it that, but it must be a center tap. They must go around the toroid core in divergent directions from the pos of the battery.
The other ends of the wires connect to the base with its 1k ohm resistor, and the Collector. The light can go one way or the other so always try both ways.

tell me when you do that, OK?

jeanna