Self running coil?

[mscoffman]

Luc,

Ha so there seem to be two choices of mosfet now.

Either the RF510;   Ciss =135pf,    Rds =0.4ohms
Or the si1026x; Ciss =60pf,    Rds = 0.7ohms  [the build in set combined]

Gyula was that in series or parallel? Also, could a 2nd si1026x be added, and by such create something like: 2* si1026x; Ciss =120pf,    Rds = 0.35ohms  [the build in sets combined] without having negative other things happening?

Now if we only could find a single one that has Ciss=<120pf,    Rds=<0.35ohm

Anyhow, a little problem [for Luc] that could happen is that the frequency factor goes so far up that he might need to put his magnet closer to the coil... So Luc, if you go for any of the above mosfet types, and you can't get a good charge back [but still notice some effect], you probably would need to come closer with your magnet. You might having a hard time for a while finding the sweet spot back again.

NextGen67

If you study the data sheet: http://www.vishay.com/docs/71434/si1026x.pdf 

Rds ohms max = 1.4
Id amps = .5
Vgs(th) min = 1
Vgs (th) max = 2.5
Vdss Volts =  60
Ciss pf Max = 30
Crss pf Max  = 3
ton ns max = 15
toff ns max = 20

And these data are for a single device and I suggested using two in parallel because they are manufactured as double devices in a single SC89 SMD case.  NextGen has just mentioned using two such SMD cases also in parallel, which would mean 4 single MOSFET in parallel, this would still have about 120pF input capacitance but Rds would be  about  .35 Ohm.

rgds, Gyula

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another selection:

STMicroelectronics  STS2DNF30L,  Dual transistor Surface mount SO-8
each transistor;
Ciss =  121pf, Rds(on) Static drain-source on resistance = 0.09ohms

[NextGen67]

---

another selection:

STMicroelectronics  STS2DNF30L,  Dual transistor Surface mount SO-8
each transistor;
Ciss =  121pf, Rds(on) Static drain-source on resistance = 0.09ohms

mscoffman, Very good

Vds 30V
Vdgr 30v
Vgs 18v
Vgs 2.5v max
Rds 0.15ohm max [0.09 typ]
Ciss 121pf
Coss 45pf
Crss 11pf

Data sheet attached.

--
NextGen67

[gravityblock]

When I click the link I am asked to logged in when I am already logged in. whats up with that?

There has been 8 downloads of this file so far.  The problem may be on your end or a temporary issue with the server.  Maybe try to log out, then log back in.  If the problem persists, then you can view or download the file on Scribd, http://www.scribd.com/doc/25248289/How-to-Build-Solid-State-Electrical-Over-Unity-Devices

If you have any additional problems, send me a PM and I'll send the file to you.  Thanks for bringing this to my attention.

GB

[LightRider]

Hi all,

here is a new video demonstrating a pickup coil and a LED as load.

Link: http://www.youtube.com/watch?v=bgPR9r14zWE

Luc

Hi Luc,

I gather the material to make a replica of your experience 
But until now, it seems that I can't make the necessary adjustments to succeed 

Would it be possible to make a video of the steps to adjust the frequency, duty cycle, voltage, space between the coil and magnet ... etc...

And of course to show your connections to your measuring devices (capacitor bank at the back with the precision 1 ohm resistor ... this part hasen't been clearly filmed).

Thanks,
LightRider

[NextGen67]

Having taken a close look at Luc's scope shots [the non tuned and tuned ones], it clearly seems to show some capacitive effects at the begin of the ON pulse [see below enlarged image fragments].

For the NON tuned scope shot:

Instead of the vertical rise and then horizontal line we would normally see in a square wave, this one is like

1) Rise (normal - start of ON signal)
2) Horizontal, but below max amplitude [ capacitance effect ?]
3) Slope up [ capacitance effect, the capacitance seems NON fixed here ?]
4) Horizontal line (normal)
5) Fall (normal - end of ON signal)

This effect takes roughly some 14+17 = 31 percent of the ON phase. It is likely that this is caused by the capacitive properties of the FET. I have no good explanation yet as of *why* the capacitance effect is build out of 2 parts [one(1) the horizontal below max amplitude, the other a slope up to max amplitude], but this might have to do with the FET's switch on technique used].

Note that the end part of the ON signal [the fall] looks rather as what would normally expect [thus no capacitance effects happening here], and this could be explained by the fact that since the energy to from the signal generator wend off, the capacitance of  the FET is 'virtually' not there anymore [the capacitance is only there when the FET is in operation modes].

The 'fine tuning' [getting optimal resonance frequency], seems to have particular strong effects on *this* part of the ON signal. ( See some posts back where I posted Luc's non tuned and tuned scope shot, but with the yellow trace inverted and moved over the green one, to make the difference clear between non tuned and tuned ).

When a better type FET is used [one with the lowest possible Ciss] the 'length' of this effect will become much smaller and thus less important... It actually would make tuning more easy, since *exact* matching becomes a less important factor.

Also, with the better type fet, it seem appear to me that the 'charge back' factor [charging up the Cap bank] would *increase* , which is of course a good thing.

As for the TUNED scope shot,

You can clearly notice that step 2 and 3 mentioned above are 'corrected' by Luc, by having an *exact* tuned frequency.

in my earlier posted scope shots [the one with the red circles], the difference is pointed out, and one can see that the non tuned one has a mismatch, and this shows *why* the cap is unable to charge up [loss of energy, due to frequency tuning mismatch].

So, basically the FET capacitance is *NOT* really so important for the charge back (since only some 31 percent [less then 3 percent! with the correct FET] are accounting for the frequency 'mismatch'

Later on [when the better type FET is used], new scope shots like these could actually give some indications as for *where* the charge back is coming from.

also, with the new type FET, the tuning will have *more* effectiveness because the tuning part could *never* 'correct' the slope [step 3] part totally, because it is a variance capacitance there[that also is why there is a little ring signal afterward]. this slope part is almost totally removed with the new type FET, thus *more* effectiveness for he tuned frequency [thus *more* charge back].

A side note for the Cap bank charging.... Although you see Luc's meter gaining upwards very quickly, the actual charge going into the Cap is still at the very low border... Charging happens with some 62.4 uA, and if my calculations are correct, this will translate in some 0.005 mW.   This will become slightly better -hopefully- with the new FET, and if after all this we still get the charging effect, the resonance coil could be tweaked for lower ohmic resistance.

P.S.: At the end of the ON signal [the fall] it shows a rather *non* direct decay at the last 20 to 25 percent of the fall edge... what effect is responsible for causing this ?

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NextGen67