Joule Thief

[Tink]

The two 470 Ohm resisters limit the current so the leds won't blow (or the transistor if it is a low amp-rated one).

[nievesoliveras]

The two 470 Ohm resisters limit the current so the leds won't blow (or the transistor if it is a low amp-rated one).

I think that I posted the wrong graphic.
This one is the correct one.

Jesus

[protonmom]

Thanks everyone for your help on the neon.  For some odd reason I had the idea that the neon took a lot of juice to light and that was why I couldn't understand why the neon would light up and not the cfl.  Anyway, I went back to the old boards and put them back together with good parts and they are working once again, along with the others.  From now on, I will be checking the alligator clips to make sure they work properly before I blame the boards for any malfunction.

[MrMag]

Bill and all the other Joule Thief experimenters,

Congratulations on reaching 1000 pages !!!!!!

Amazing how a simple little circuit can bring about so much discussion. Great job guys!!

[resonanceman]

It is simple. The current flows where there is less resistance.
The space between the neon filaments is less than rhe space between the cfl filaments.
Less space means less resistance.
The current choses the neon and the circuit has not enoufg juice to light both devices.

Jesus

I agree......... I will add that a neon takes around 90V to light
and doesn't need much power.
A CFL takes more like 250V to light and requires more power.


gary