Joule Thief

[Pirate88179]

@MK1:

That is really cool.  I have been subscribed to that guy for a little while now.  he does some nice work.

@ Jeanna:

Thank you for the input.  I will use your winding recommendations on this one.  Since this same tube lit pretty bright on the Fuji, I would think that your circuit will do an even better job of it.

Thanks,

Bill

[crowclaw]

@ jeanna,

Sorry for not coming back to you sooner.  An additional  winding on my JT, 4 turns of mag wire  = 22 volts. BTW, I made a mistake with the output voltage it is infact just under 300volts I had not calibrated the scope probe!
This JT configuration... is 28T+28T, 5k base and BC547 transistor. frequency = 5.7kHz. with 9 strand insulated hook up wire. I agree as you have suggested, large power transistors are not necessary when looking at higher amplitude output voltages. It  depends on the  number of primary/secondary turns affecting  the switching currents and hence the current handling capacity through the CE junction of the device, plus the base current required to turn it on. This is the majority of your draw current. Incidental I have an old analogue milli_amp meter I use in series with the source battery.  Regards M

[crowclaw]

@ Bill

High Bill, We are experiencing the worst weather conditions in the UK for well over 30 years
Deep snow in many regions with temperatures of -17 C. Satellite Pic's show GB white over. M

[kooler]

question
i just torn down a rockford fosgate amp
and ripped the toroid in it out
with 9 turns on the secondary i get 60 volts dc
the collector has 5 turns and the base has 3 turns
and the transistor gets very hot hot hot
mpsao6 i have got 10 volts bemf on collector
" what am i doing wrong.." do i need more turns on the collector windings
reducing the turns still gets it hot
it will run with one turn on base but still gets hot

[jeanna]

Hi kooler,
I would raise the base resistor to a higher value first.

jeanna