RE: [TCML] NST Measurements

["Lau, Gary" <Gary.Lau@xxxxxx>]

Bart wrote:
> My measured output at 120.2V input was 16390 which is a voltage ratio of
> 136 (not 125 as spec'd).

I wonder what the secondary voltage would measure if it were loaded with a 30mA load?  Unfortunately that requires a 500K/750W resistor - not something I have in my junkbox.

How linear is the 136X forward ratio over the 0-120V input range?  Could a much lower wattage 500K load be used at a reduced input voltage to predict the full-power loaded voltage?

Regards, Gary Lau
MA, USA

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of bartb
> Sent: Tuesday, January 20, 2009 11:53 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] NST Measurements
> 
> Hi All,
> 
> I made some extreme low voltage measurements:
> 
> Feed      Meas.      Integer
> Vsec      Vpri       Ratio
> -----     -----      -----
> 120.2     684mV      176
> 110.5     625mV      177
> 100.7     565mV      178
> 090.1     502mV      180
> 080.5     445mV      181
> 070.5     386mV      183
> 060.1     326mV      184
> 050.4     271mV      186
> 040.6     216mV      188
> 030.1     158mV      190
> 020.1     104mV      193
> 010.2      52.5mV    195 **
> 008.15     42.1mV    194 **
> 006.06     31.1mV    195 **
> 004.02     20.6mV    195 **
> 002.106    10.8mV    195 **
> 001.069     5.5mV    194 **
> 
> This data presents some obvious questions.
> 
> When I managed a low enough level (10V down to 1V), the voltage ratio
> showed about 195 consistently (what was affecting the voltage ratio
> seems to have stopped). Did I manage to get below shunt inductance
> influence? Is it possible the turns ratio is 200, yet the voltage ratio
> is entirely something different thanks to the shunts at greater voltages
> (and the manufacturers account for this in their Voc rating)?
> 
> My measured output at 120.2V input was 16390 which is a voltage ratio of
> 136 (not 125 as spec'd). Voltage ratios and assumed turn ratios are very
> different. There is now no doubt about that, but still, how to determine
> the real turns ratio is a mystery (and maybe not possible?).
> 
> Bart
> 
> bartb wrote:
> > Hi Dave,
> >
> > Yes, I agree. The magnetic shunts are causing the non-linearity. As I
> > mentioned a moment ago in my reply to Phil, the voltage ratio is
> > non-linear because of this. Were trying to use the voltage ratio to
> > determine turns ratio. This won't work "IF" the shunts have influence
> > because it affects the voltage ratio. I think everyone measuring is
> > seeing this affect.
> >
> > The problem I have is the inductance factor is based on the turns
> > ratio. So, how to remove shunt influence? The only way I can think of
> > is to use "extreme" low voltages. Maybe instead of inserting 120Vac to
> > the secondary, we need to bring down the voltage to something between
> > 1 and 10V input to the secondary and measure the millivolts at the
> > primary? There must be a point at which the shunts have little affect
> > and the voltage ratio becomes linear enough for a decent approximation.
> >
> > Take care,
> > Bart
> >
> > sparktron01@xxxxxxxxxxx wrote:
> >> Bart
> >>
> >> Is it possible that the inductance varying is hosing the apple cart?
> >>
> >> Instanteous voltage for an inductor (complete) is:
> >> V = iR + L (di/dt) + i (dL/dt)
> >>
> >> The last term in "linear" circuits tends to zero and (usually) has
> >> no bearing on circuit.  But with a magnetically shunted circuit
> >> the third term starts influencing the second, and vice versa
> >> (i.e the whole circuit becomes VERY non-linear...)
> >>
> >> Regards
> >> Dave Sharpe, TCBOR/HEAS
> >> Chesterfield, VA. US
> >
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla