Self running coil?

[gotoluc]

Excellent scope pic's. Well both the signal and the noise has to flow
through the terminating resistor and the signal is winning power wise
with the resistor. Notice how the signal *Transistions* are much more
rapid and much squarer. The Fourier decomposition to sinewaves
would show much greater high frequency action with the squarer wave. 

The other thing is that clearly your coil seems to be resonating at
the frequency you are driving it at. This is seen in the one to one
lower power sinewave base seen in the gate current. The pulses
are due to coil inductance. The sinewave is due to coil re sonace and
you are *not* seeing it in the generator voltage with the t-resistor.
The coil power is beginning to overpower the transistor. And that
is beginning to effect your signal generator leads as noise in those
drooping high levels. With the cleaner signal you can tell that
the resonance sinewave is not a function of drive voltage.

On the NE555 how are you powering it? It may make sense to use
an external ~5volt dc supply for the NE555 then a voltage divider
to set the voltage. for comparison to the SigGen. You need to look
at the *exact upper and lower gate voltage levels* If you just want to
convert the signal to be *more* sinewave like and slower use an RC filter.
Hopefully you have already tried that gate series variable resistor. ie VrCiss =
RC when used with the NE555. In this circuit you won't necessarily get any
operational browny points for using clean digital signal level drives. It's
nicer to look at though. RC filter = series resistor then cap to ground.
put the scope on the actual gate. If you still come up with the same
answers then perhaps OU is based more in coil resonance and less in
the high speed inductive kick?

So:

a) set up variable gate resistor, tune with t-resistor vs tune with remote
powered NE555. Should be same. Also *maybe* same now as witout Vr and
t-resistor.

b) Set up RC filter, tune with t-resistor vs tune with remote powered NE555
Should be the same. Also should be same now without RC filter and
without t-resistor.

c) NE555 under remote power vs NE555 under bulk or pickup power with
voltage set exactly the same - difference in operation? = difference of
power drain of NE555 on operation of circuit.

:S:MarkSCoffman

Hi Mark.

I think we are getting closer to what is needed to make this circuit work.

If I use the 555 and match the pulses to the exact specs as the Wavetek output (I mean perfect match) and connect the 555 to the gate then the sine wave is gone and so is the coil sending back energy. I connect the Wavetek and all is back.

Something inside the Wavetek is allowing the gate to switch and the coil resonance to come through the switch and shunt resistor. Using the 555 it loses this since you don't see the sine wave on across the shunt resistor, which maybe a braking effect on the resonating coil.

Could it be that the Wavetek output has an impedance matching transformer and this is what is helping not to cancel the coils resonance as what is leaking trough the switch is resonating in the Wavetek impedance matching coil?

If this is what is happening then the sine wave that is going back through the shunt resistor should not be calculated as power that is coming from the generator but rather from the coils supply.

Are you following me on this? Let me know what you think

Luc

[mscoffman]

Hi Mark.

I think we are getting closer to what is needed to make this circuit work.

If I use the 555 and match the pulses to the exact specs as the Wavetek output (I mean perfect match) and connect the 555 to the gate then the sine wave is gone and so is the coil sending back energy. I connect the Wavetek and all is back.

Something inside the Wavetek is allowing the gate to switch and the coil resonance to come through the switch and shunt resistor. Using the 555 it loses this since you don't see the sine wave on across the shunt resistor, which maybe a braking effect on the resonating coil.

Could it be that the Wavetek output has an impedance matching transformer and this is what is helping not to cancel the coils resonance as what is leaking trough the switch is resonating in the Wavetek impedance matching coil?

If this is what is happening then the sine wave that is going back through the shunt resistor should not be calculated as power that is coming from the generator but rather from the coils supply.

Are you following me on this? Let me know what you think

Luc

Yes, I think it has something to do with the
100 ohm resistor in the ground lead of the signal
generator. The sinewave is possibly fake as current
goes.

Is the NE555 grounded? Or is it grounded through
100ohms?
Is the NE555 remotely powered by a dc supply?

Try implacing and unimplacing a 10.0ohm resistor
across the 100ohm resistor and see if that doesn't
cause a relative decrease in the ratio of this sinewave
to the rest of the signal. Try to see if shorting the
100Ohm resistor changes circuit OU behavior.

Try attaching a 100ohm resistor in the ground lead
of the NE555? Finally it may be time to implement
the opto remotely powered by a dc supply. That
should behave just like the NE555 when led is
driven by signal generator. You know a 1:1
isolating transformer in the SigGen leads could
show something too.

If the NE555 is grounded then the output driver
impedance of the NE555 can inhibit formation of that
sinewave but the mosfet transistor may be reverse
amplifying it when it exists. Making a resistor-to-
ground makes the NE555 effectively less powerful.
Also try leaving the SigGen Ground in place when
operating with the NE555.

Something in the above should help determine the
problem. The main things are the probable grounding
of the NE555 and the probable bulk capacitor or
pickup coil suppling the NE555 power.

Secondary is 100ohm resistor in the ground lead
of the signal generator. Or some 60Hz AC pickup
in the ground lead of the signal generator. Or a
SigGen signal on the ground lead between it's
ground and utility ground.
 
:S:MarkCoffman

[forest]

To eliminate ground you have to connect 555 to capacitor bank as a power source.
Can you precharge capacitors , connect 555 into it ,connect battery for a moment to start oscillations and look what next ?

[gotoluc]

Hi everyone,

I have an update video: http://www.youtube.com/watch?v=1Gy-kkJKNOU

Scope shot is from video test.

Luc

[gravityblock]

Tutorial of Series and Parallel LC Resonant Circuits, http://www.scribd.com/doc/28956060/Resonance-Tutorial

[Edit:]  @Luc, Good update on the SK2806-01 Mosfet and the modem transformer to self-oscillate with the sine wave.  Good work!

GB