The Master Of Magnetics "Steven Mark"

[ronotte]

Meggerman & other,

I do obtain BEMF over the scope screen size (more than 700V) in similar conditions!! 

Listen to Otto...the key is in using a VERY VERY FAST  & HIGH CURRENT (low input capacitance) latest generation MOSFET = IRF 840 ...... I personally do use IRFP450 because I already had a lot of them  (Their are similar but the 840 has a faster rise time i.e lower input cap).

Roberto

[innovation_station]

hello all


if i could add a few words

in ordor to even begin to understand any thing one must read everything you can!  this was not at all spelled out as easyly for me or otto or others as it is now for you

we all must realize that this is far from a toy  if you truly have an intrest in this research you WILL READ ALL YOU CAN  many many times this is as sauron said the easy way i myself did not walk the same path you all now can we all have so verry much more to learn about this new and old alike

if for some reason you thought this would be an easy project  you were wrong!!!
there is so verry much more to it

you all have just begun to walk the many many steps to the finish line

we must understand everything about this to be safe with it

if you can not understand thease few basic test you will only become confused when this starts to get tough

this is the easyest part along the way please take the time to read everything you can as i have and many others have too

but as i said i have so verry much more to learn and i am far beond many of you the learning will never end on this tech
please do not rely on otto to show you

you must discover for yourselvs  please READ ALL YOU CAN!!

[bob.rennips]

Meggerman & other,

I do obtain BEMF over the scope screen size (more than 700V) in similar conditions!! 

Listen to Otto...the key is in using a VERY VERY FAST  & HIGH CURRENT (low input capacitance) latest generation MOSFET = IRF 840 ...... I personally do use IRFP450 because I already had a lot of them  (Their are similar but the 840 has a faster rise time i.e lower input cap).

Roberto

Excellent. Now try without the collector going through the center of the coil. Everything else exactly the same. What voltage measurement do you get ?

[bob.rennips]

Hi Otto,
Are you using a bench power supply or battery?
I was wondering if the spikes you are seeing may have come from a secondary winding of your PSU. You need to scope your supply possibly.

Are you getting any kind of current to go with these 400V spikes?
Is the 400V measured across the lamp?
What frequency and duty cycle?

I am amazed you can get such a large back emf with so few turns, no ferrous core and only 12v.
Look forward to seeing your scope shots.

Regards
Rob

Good thinking. I'm using a standard sized car battery.

What are other people using for a power supply ?

[Jdo300]

Hi Otto,

Thank you for the clarification on the circuit diagram. That definitely clears up the TON of confusion that I was experiencing 

@bob,

I'm going to be retesting this circuit as soon as I get home and you can bet that I will post lots of scope shots and photos (I'll probe it to death).

@Otto,

Ok, one quick thing, what pulse width did you use to get your best results? I'm assuming a very short pulse as I have been able to get 350+V spikes on some of my TPU experiments with extremely short pulses.

Also, I know someone else asked this but it would help to know how much amperage you are pushing through the coils. The 25V power supply I am using is current limited at 0.5A, though a simply 9V battery will push an amp easily (but it's only 9V though). So having some idea of the current requirement will make accurate replication easier too.

Finally, having some idea of the frequency range you are working in would help. We know that everyone's coils will have a different 'sweet spot' but were you finding this in the low kHz, 100s of kHz or MHz range?

God Bless,
Jason O