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Author Topic: Self running coil?  (Read 301313 times)

gotoluc

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Re: Self running coil?
« Reply #30 on: March 14, 2010, 12:32:33 AM »
Well, it's no go with the 10K resistor on the 555 output and the mosfet gate :P

Back to the drawing board ;D

Luc

Magluvin

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Re: Self running coil?
« Reply #31 on: March 14, 2010, 12:39:51 AM »
Ok so we know something.  I need to get rid of my 10k resistor. lol

I wonder if you can put a pickup coil on the opposite end of that magnet without disturbing the tcore.

Mags

Magluvin

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Re: Self running coil?
« Reply #32 on: March 14, 2010, 12:41:54 AM »
Heck  try the 12v in the cap. Run it all on the cap. give it an alligator clip.  the effect may be better at higher volts.

Mags

gotoluc

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Re: Self running coil?
« Reply #33 on: March 14, 2010, 01:26:06 AM »
Ok so we know something.  I need to get rid of my 10k resistor. lol

I wonder if you can put a pickup coil on the opposite end of that magnet without disturbing the tcore.

Mags

I've mentioned that anything ferromagnetic brought close to the Toroid coil affects it. Seems to be an indication of a Resonant state.

Luc

gotoluc

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Re: Self running coil?
« Reply #34 on: March 14, 2010, 01:30:12 AM »
Heck  try the 12v in the cap. Run it all on the cap. give it an alligator clip.  the effect may be better at higher volts.

Mags

I've also mentioned that 2.80vdc is about the maximum voltage the input can be. Anything higher and it starts to consume current from the input capacitor.

Luc

Gyula has explained this at the Energetic Forum:

The 2.8V limiting is explained by the drain-source capacitance change vs drain-source DC voltage: if the voltage is increased the capacitance decreases, hence the resonant frequency of the LC circuit created would also change. But because the input frequency does not change from the 555, the voltage on the drain side should stay where is was earlier, if it is changed by force from outside for instance then the drain-source capacitance would also change so the parallel LC resonance high impedance would suffer where the max voltage come from.

Gyula

Magluvin

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Re: Self running coil?
« Reply #35 on: March 14, 2010, 01:33:57 AM »
Well could the resonant freq of the coil be changing as the voltage there rises? Could it be possible to follow the ring with the freq gen?

Mags

gotoluc

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Re: Self running coil?
« Reply #36 on: March 14, 2010, 01:52:16 AM »
Well could the resonant freq of the coil be changing as the voltage there rises? Could it be possible to follow the ring with the freq gen?

Mags

Frequency change is one part of Gyula's explanation that is not quite so. I did experiment with changing the frequency as the voltage rises some days ago. The best score was 2.83vdc. Anything higher than that it starts to consume current from the cap bank no matter how much tuning I do.

I wish it was not so but it is.

Luc

Magluvin

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Re: Self running coil?
« Reply #37 on: March 14, 2010, 02:24:26 AM »
Hey Luc
Just one more thing,  what is the voltage of the output pulse from the 555 on the gate of the fet?

Mags

gotoluc

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Re: Self running coil?
« Reply #38 on: March 14, 2010, 02:58:23 AM »
Hey Luc
Just one more thing,  what is the voltage of the output pulse from the 555 on the gate of the fet?

Mags

Scope says 10.25vpp and 3.75vrms with 20% Duty at 20KHz

Luc

gotoluc

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Re: Self running coil?
« Reply #39 on: March 14, 2010, 03:04:53 AM »
Hey Mags,

maybe we can work on this idea: http://www.youtube.com/watch?v=rLDgQg6bq7o

Seems strait forward ;D

Luc

ramset

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Re: Self running coil?
« Reply #40 on: March 14, 2010, 03:52:32 AM »
Well
My rejoined reciprocating angle arm
Blew out at the Deflatchulater Or I would definitely be in!

Very funny Luc [very]

Chet

Magluvin

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Re: Self running coil?
« Reply #41 on: March 14, 2010, 05:25:53 AM »
Hey Luc

Actually I had sent that to a few people earlier today, I initiated the link as to say that it explained an idea that they had and that this guy did it already.
Here is his other one that adds to the vocabulary even more. Starts the same but a bit better lingo as it goes.

http://www.youtube.com/watch?v=lVZ8Ko-nss4&NR=1


Magslaffs

Omega_0

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Re: Self running coil?
« Reply #42 on: March 14, 2010, 09:11:32 AM »
Thanks for clearing up the mosfet doubts.
I noted that the trace is exactly the same with coil disconnected, so the coil is essentially acting as an open circuit. One reason could be the high time constant (L/R) of the circuit. We don't have circuit diagram here, still assuming L=44mH, R=1ohm, V=1.2V, we get L/R as 44 ms.

Frequency is 18kHz so pulse cycle is 0.055 ms. and pulse on time is 55.5*22/100, or 0.012 ms.

Imax will be 1.2/1 = 1.2 amps
I at the end of 0.012 ms will be 1.2*(1-e^(-0.012/44)) = 0.0003 amp or 300 microamps !!

So you can see that the current rises to 300 uA and the pulse switches off. There is not enough time for the current to rise beyond your scope's detection threshold and it shows it as 0, which is right as 300 uA is practically 0.

You will need about a 100V supply to see any current flowing there. I'm pretty sure that the coil is not generating anything and merely acting as an open circuit, it can't switch on due to very high inductance and L/R and low voltage and tiny pulse width.

But I don't want to discourage you or anyone, so I'm leaving this thread now. It seems you did not like us "correcting" you, anyway. So simply assume that I'm wrong and go ahead, all the best.....
« Last Edit: March 14, 2010, 12:40:06 PM by Omega_0 »

gyulasun

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Re: Self running coil?
« Reply #43 on: March 14, 2010, 11:10:12 AM »
Hej Omega_0,

Please do not leave this thread... lol  You (or others) here need not feel the 'need for leaving'.  As long as conventional explanations are correct and scientific for clarifying the operation of a circuit, anybody should be welcome to come forward with correct contributions.

I agree with your calculations, one addition is Luc measured his toroidal coil DC resistance as 6.8 Ohm so the peak current was 1.2/6.8=0.176A and the the current at the end of 12ms was 322uA but this pretty much the same low current you got with the 1 Ohm assumption.

rgds,  Gyula

EDIT:  Just noticed, member EMdevices calculated the same order of small current (he got 350uA) at another forum.
« Last Edit: March 14, 2010, 12:25:55 PM by gyulasun »

gotoluc

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Re: Self running coil?
« Reply #44 on: March 15, 2010, 07:02:42 AM »
Thanks for clearing up the mosfet doubts.
I noted that the trace is exactly the same with coil disconnected, so the coil is essentially acting as an open circuit. One reason could be the high time constant (L/R) of the circuit. We don't have circuit diagram here, still assuming L=44mH, R=1ohm, V=1.2V, we get L/R as 44 ms.

Frequency is 18kHz so pulse cycle is 0.055 ms. and pulse on time is 55.5*22/100, or 0.012 ms.

Imax will be 1.2/1 = 1.2 amps
I at the end of 0.012 ms will be 1.2*(1-e^(-0.012/44)) = 0.0003 amp or 300 microamps !!

So you can see that the current rises to 300 uA and the pulse switches off. There is not enough time for the current to rise beyond your scope's detection threshold and it shows it as 0, which is right as 300 uA is practically 0.

You will need about a 100V supply to see any current flowing there. I'm pretty sure that the coil is not generating anything and merely acting as an open circuit, it can't switch on due to very high inductance and L/R and low voltage and tiny pulse width.

But I don't want to discourage you or anyone, so I'm leaving this thread now. It seems you did not like us "correcting" you, anyway. So simply assume that I'm wrong and go ahead, all the best.....

Hi Omega,

please don't think that I'm not looking for corrections. This was the very reason I started the topic and why I had the ? at the end of the topic title.

Electronics is not my strong side so when I find an effect I usually ask for opinions from everyone. I have no problem learning something new.

@everyone, I may have been to quick to conclude when I added the 10K Ohm resistor on the 555 output. I looked at it today with the scope and it's way to much resistance for the mosfet gate to operate. It looks like the maximum resistance that can be added without affecting the gate would be around 200 Ohms.

I'm testing a few other things and will post what I find in a few days.

Thanks for all your interest and help.

Luc