Joule Thief

[jeanna]

@xee,

I think your guess that the voltage was marginal was probably correct. I still recommend adding more turns to the pickup coil. I think your problems will go away if you add at least another 100 turns.

This is probably correct, but it is not an easy thing/ not possible to 'add' turns to an MK1 type pickup.

I will think about doing another with more turns, but later.

@theNOP

I have a wimhurst machine and it barely glowed this fluoro light, so, I am not sure this is the answer either.

It is surely involved, but the voltage was very high passing through the tube. I could feel it on my fingertips. Perhaps the magnet delivers a spark in the right way to switch the light on.

It has been 3 hours and the light is still on in just the same way as before.


jeanna

[Mk1]

@all

Really nice site , with basic magnetic and electric laws , with animation , so nicely done worth a look , its like a 101 experiment book .

http://micro.magnet.fsu.edu/electromag/index.html

[Thaelin]

   Thanks Nop:
   Was not sure if it would. That clears that up then.

thay

[the_big_m_in_ok]

xee2 said:

...Two 47 uF in parallel is 94 uF at half voltage. ...

@xee2,
Not to be critical, but I might be missing something?

If the positive and negative rails maintain the same voltage, the voltage across the capacitors should be the rail voltage with the capacitance doubled as you said?

If they were in series, the capacitance is half, but voltage the same across each positive and negative terminal, doubling the tolerance for both combined, which would be reasonable to me.  You did say or imply that?  I do agree with that part, then, if you did.

[xee2]

@ the_big_m_in_ok

xee2 said:
@xee2,
Not to be critical, but I might be missing something?

If the positive and negative rails maintain the same voltage, the voltage across the capacitors should be the rail voltage with the capacitance doubled as you said?

If they were in series, the capacitance is half, but voltage the same across each positive and negative terminal, doubling the tolerance for both combined, which would be reasonable to me.  You did say or imply that?  I do agree with that part, then, if you did.

Yep. I got carried away with a quick answer.

It is the voltage rating of the pair of capacitors compared to the voltage rating of a single capacitor. Two caps in series will handle twice the voltage of a single cap before blowing up.

For parallel caps the voltage at which they blow up stays the same. It does not get cut in half.

Thanks.