Joule Thief

[Pirate88179]

@ ist:

I have taken apart cfl's before to get parts once they quit working.  Of course, this is dangerous because if you break the tube, the mercury leaks out and you are supposed to call a hazmat team to do the clean-up. But, I was thinking. (also dangerous)  Somewhere in there is a transformer to convert 120 v ac to whatever the bulb needs to light.  We already know it will light on dc at the right freq.  So, my thought is.....can we by-pass the ac stuff and put our power in and still use the high freq. transformer to get it to light with an AA bat or something else small dc?  It is just a small pc board in there with a minimal amount of components.  I just think that if we put our dc in at the right point, it will still light.  Maybe have to use a JT circuit before going in, I don't know.  What do you think?

Bill            PS  I am playing music and watching my Christmas tree light up using my $15.00 board and components from Electronics Goldmine.  It works great!  It is driving 200 leds and 80 incandescent bulbs on three frequencies and also responds to volume/amplitude.  This was a great project.  (all projects are great when they work)

[WilbyInebriated]

yes you can do exactly that bill, remove the AC circuit and just hit the tube with high voltage to light it.

edit: i may have misunderstood, were you suggesting stepping up a 1.5V to 120V and then running the cfl from that? that should work too, although i think you have more losses going that route instead of just going from 1.5V to 350V or higher.

[Pirate88179]

@ Wilby:

No, you had it right before.  I was just thinking of lighting the cfl tube from 1.5 volts dc....no 120vac at all.  It may not be full brightness but...I still think it would be cool.  Any idea of what part/parts to by-pass on the round pcb?

Bill

[WilbyInebriated]

i'd say all of it. just go right to the tube itself. i would think one of those 1.5 to 350V inverters would do it just fine. just try and stick to the lower wattage variety. like groundloop said earlier, there is a limit to how big you can go.
you can also do the inverse, if you break the cfl twist bulb, you can use the circuit to drive a plain old tube.

[Pirate88179]

@ Wilby:

Thank you.  I think I'll give it a go.  What's the worst that could happen?  Wait, don't tell me.... ha ha


Bill