Joule Thief

[xee2]

Some more tests on the 120 VAC LED bulb LaserSaber is using (current reduction tests):

video >>>>> http://www.youtube.com/watch?v=nKj4FGB2AyA

[Groundloop]

xee2,

Nice test. :-)

Do you know if those small LED bulbs (for 110VAC in US and for 230VAC in Europe)
have a IC circuit in the socket?

Also, do you get a lot of audio noise when running the transformer
circuit?

I did try to add a 5K variable resistor with a capacitor in parallel in my circuit, but every time I get some
"good" current usage with a reasonable good output to the LED lamp, then my transistor blows. So far I have
only been able to run my circuit at low voltages. I guess that when I add a series capacitance to my
transistor base then the core itself is free to oscillate, thus creating voltages that exceed the transistor
safe operating area. :-)

GL.

[xee2]

Do you know if those small LED bulbs (for 110VAC in US and for 230VAC in Europe)
have a IC circuit in the socket?

Also, do you get a lot of audio noise when running the transformer
circuit?

The Radio Shack transformer I am using does not make any noise at all. I suspect there is a full wave rectifier and maybe a transformer in the bulb, but I have not taken one apart.

[Groundloop]

xee2,

Thank you for taking time to answer my questions.

Tonight I did try out the attached circuit. The advantage of this circuit is that
we do not waste the base current since this current also must go through the
power coil. Same goes for the trigger coil current to the base. I'm now using
the BUX98A transistor, rated at 1000 Volt. At 4 Volt @ 0,35A current my 1,8 Watt
led bulb did go to approx. full brightness. So the circuit run very efficient.

I'm now working to find a way to pulse the Ferrite core without blowing up the
transistor. (Has blown up 5 transistors today.) Every time I try to find some
ferromagnetic resonance then my transistor blows up. Every time..............

GL.

[xee2]

@ Groundloop

That BUX98A looks very interesting.