Joule Thief

[xee2]

Thanks xee2
answer!

for which these details are needed in the scheme of JT?

100 uf is not needed. Other parts are needed for measuring voltage but not for lighting neon.

[xee2]

@ kooler

Five neons seems to work better than four (fails to fire less often), and of course gives bigger sparks.

[crowclaw]

@ All,
Regarding JT circuits, there seems to be  misunderstandings between the nature of the waveform being produced from this circuit. I notice on various threads the term AC being mentioned when in fact the waveform is a series of very narrow positive going pulses. The on time period compared with the off time period is considerably small, (known as the mark / space ratio) these very narrow pulses give rise to low operating current demands. An AC waveform has a  completely different characteristic altogether. This waveform rises in a positive amplitude from a zero axis then falls and continues in a  reverse direction below the zero axis to produce a negative amplitude... this sequence repeats at the oscillating frequency. The oscillator circuits that produce these waveforms are of a different design from that of the JT commonly used here.
For further understanding regarding the nature of various waveforms for those who are unfamiliar take a look here.
http://www.allaboutcircuits.com/vol_2/chpt_1/1.html

[jeanna]

..... I notice on various threads the term AC being mentioned when in fact the waveform is a series of very narrow positive going pulses. The on time period compared with the off time period is considerably small, (known as the mark / space ratio) these very narrow pulses give rise to low operating current demands. ....

You are correct in much of what you are saying and I have learned a great deal since a year ago when I wanted to use the term AC

What you must have missed is that very often, and frequently when using the MK1 designs, or conical etc, the waveform is NOT all on the positive side.
So, while what you say in general about being able to use the volts with a very low amps need is true, what you have assumed about what we are getting for the waveform, is incomplete.

Thank you,

jeanna

[jeanna]

for which these details are needed in the scheme of JT?

Hi zhak,
I agree with what xee2 said, and I will repeat it.

These 3 things marked in red are not necessary for a jt.
I do not use them when I make 1,000v or 2,000v joule thief lamps.
xee2 uses them for measuring and boosting, and I do not.

thank you,

jeanna