Re: [TCML] SRSG "sputter"

[Joe Mastroianni <joe@xxxxxxxxxxxxxx>]

Hi Gary,

Actually I was.  I had to set the variac to "0" to get the motor to sync, but if I applied power I'd get pretty bad output.  I'd have to rotate the dial to what it called "20" volts to get proper output.
I just moved to a propeller gap.  I'm seeing something different, which I presume is a result of the mechanical adjustment.   I get full output at close to "0", but then I get some arcing across the safeties.  If I move the variac to 10, I can get to full power smoothly.
I just put a video here  <http://yfrog.com/2opropellerrunz>
Thanks again for all the help,

Joe

On Jul 11, 2010, at 7:43 PM, Gary Lau wrote:

> Hi Joe,
> 
> Yup, your Freau adjuster appears to be doing just what it should.  What size
> cap do you have across the motor?  I think you could get more range of delay
> with a larger cap..
> 
> I think the sanity check discussion came about because after you adjusted
> the mechanical phase, you weren't getting the performance that you saw when
> you were getting the sputtering, so I wanted to be certain that the motor
> phase was being affected.  That makes me think that the phase may still not
> be hitting the sweet spot.  With my Freau adjuster, when the phase Variac is
> all the way CCW (no phase delay/zero inductance), the sparks are very small,
> despite 100% power Variac.  I increase the phase delay, the sparks smoothly
> grow longer and longer, until the safety gap fires and it becomes very
> erratic.  Backing off slightly, that's the sweet spot.  Do you see something
> like this?
> 
> Regards, Gary Lau
> MA, USA
> 
> On Sun, Jul 11, 2010 at 6:29 PM, Joe Mastroianni <joe@xxxxxxxxxxxxxx> wrote:
> 
>> HI Gary -
>> 
>> Ok - some measurements available on YFrog
>> <http://yfrog.com/13t2qj>  This is the maximum phase shift I've measured.
>> What you're seeing is the sine wave from utility power against a distorted
>> triangular wave.  This is the voltage between my household hot lead (black)
>> and the household neutral lead (white).
>> 
>> That triangle wave is measured from the point where the variac L output
>> connects to the run cap and feeds into the motor relative to the neutral
>> connection (white).  So the motor is across the neutral and this point which
>> I am measuring.  Notice the maximum phase shift appears to be between 1.2
>> and 1.6ms (lets say 1.4).  That would put the max phase shift, as measured
>> from the power supplies, at 360*1.4/16.67 = ~30 degrees.
>> 
>> Now, we could argue that the waveform from the power supply going into the
>> motor may somehow not relate directly to the motor timing angle.  Ok, I
>> would kind of wonder why that might not be so, but for the sake of argument
>> I have added these videos.
>> 
>> I attached 2 rectangular neodymium magnets to 2 of the rotating tungsten
>> rods on the SRSG wheel  with wire ties.  I then wrapped 20 turns of 26gauge
>> magnet wire around one of the stationary tungsten electrodes.
>> 
>> The first video shows 2 waveforms.  <http://yfrog.com/0jrelmotdrivez>
>> Channel A is the power feeding the motor, out of the variac/cap circuit.
>> Notice how that waveform distorts as the variac L is progressed from "0" to
>> about 1/2 way.   Channel B is the voltage "blip" taken off the coil as the
>> magnets rotate past.  I think we can presume TDC is when the magnet/timing
>> waveform crosses "0".  I rotated the variac until the motor began to lose
>> lock (you can hear it in the background, and see the waveform begin to
>> oscillate).  Notice the magnet pulses do not change phase with respect to
>> the power supply to the motor, even though that voltage waveform begins to
>> distort when the variac L is moved off "0".
>> 
>> The second video shows 2 waveforms.  <http://yfrog.com/bcrelutilz >
>> Channel A once again is public service power, taken from the feed to the
>> coil.  Channel B is the voltage taken off the 20-turn magnet wire, measuring
>> the passage of the magnets attached to the spinning tungsten electrodes.
>> Here you can see the phase change quite dramatically, and it's clearly
>> about 30 degrees before the motor loses lock.
>> 
>> Apologize for the video quality - this is taken from my iPhone as I kneel
>> beside the coil and rotate the variac.
>> 
>> Hope this data is useful.
>> 
>> Cheers,
>> Joe
>> 

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