TSSP: List Archives

From: "Barton B. Anderson"
Date: Thu, 16 May 2002 19:40:12 +0000
Subject: Re: [TSSP] Topload breakout potentials

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Hi Paul,

Paul wrote:

> Bart's secondary Fres was about 5% higher than predicted, which is
> a big discrepancy.  I had the walls at 60" and the roof at 120".
> I took these away altogether and got
>
>      Measured     Modeled      Error
> ba0:  69.8 kHz    69.9 kHz     +0.1%
>
> which is more like it.  I guess that even though there is a wall
> and a ceiling present, they are not terminating much of the E-field.

The wall nearest the coil is the garage door. Rather thin plywood (built
in the 60's). The ceiling is wood also and is at an incline from the
edge. The 120" measurement is nearest edge above the toroid. The farthest
edge of the toroid to ceiling is 142". FWIW, ETesla6 predicted ~68kHz.


> Bart's coil present an even bigger mystery now, because as well as
> the good match on the secondary we also have for the primary
>
>      Measured     Modeled      Error
> ba0:  61.3 kHz    61.5 kHz     +0.3%
>
> so the -12% tuning is genuine and we ought to be getting less than
> 17kV/cm on the toroid.
>
> Is there any possibility that some resonant effect in the charging
> circuit is giving a larger than expected bang?  Bart, can you confirm
> the toroid dimensions 30"x9", sorry if I've asked before but so
> much stuff crosses my desk at the moment I'm losing track!

No problem, any time. Yes, it's 30" outer edge diameter and 9" cord.

I thought you had the coil up around 26kv/cm after the surface gradient
doubling error or was that prior to the 12% differential? BTW, my gap
rate is 4.17ms and charge time is 6.33ms, so the cap should charge to a
time constant of 3.3 or 97% of Vp. This should lower the Vp at the cap to
14.8Vp and 6.69j (if you want to pull bps in, but that can get messy
fast).

I grabbed a low Fr current sense transformer from Digikey this week.
Maybe I can use it as an input current measurement temporarily (it's good
only up to 30A, so I'll have to be careful). Also, can this be used for
secondary base current or would I need a high Fr current transformer? I
think this ones spec'd at 50 to 400 Hz.

Take care,
Bart

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Hi Paul,
Paul wrote:
Bart's secondary Fres was about 5% higher than predicted,
which is

a big discrepancy.  I had the walls at 60" and the roof at 120".

I took these away altogether and got
     Measured     Modeled     
Error

ba0:  69.8 kHz    69.9 kHz    
+0.1%
which is more like it.  I guess that even though there is a wall

and a ceiling present, they are not terminating much of the E-field.
The wall nearest the coil is the garage door. Rather thin plywood (built
in the 60's). The ceiling is wood also and is at an incline from the edge.
The 120" measurement is nearest edge above the toroid. The farthest edge
of the toroid to ceiling is 142". FWIW, ETesla6 predicted ~68kHz.

 
Bart's coil present an even bigger mystery now, because
as well as

the good match on the secondary we also have for the primary
     Measured     Modeled     
Error

ba0:  61.3 kHz    61.5 kHz    
+0.3%
so the -12% tuning is genuine and we ought to be getting less than

17kV/cm on the toroid.
Is there any possibility that some resonant effect in the charging

circuit is giving a larger than expected bang?  Bart, can you
confirm

the toroid dimensions 30"x9", sorry if I've asked before but so

much stuff crosses my desk at the moment I'm losing track!
No problem, any time. Yes, it's 30" outer edge diameter and 9" cord.
I thought you had the coil up around 26kv/cm after the surface gradient
doubling error or was that prior to the 12% differential? BTW, my gap rate
is 4.17ms and charge time is 6.33ms, so the cap should charge to a time
constant of 3.3 or 97% of Vp. This should lower the Vp at the cap to 14.8Vp
and 6.69j (if you want to pull bps in, but that can get messy fast).
I grabbed a low Fr current sense transformer from Digikey this week.
Maybe I can use it as an input current measurement temporarily (it's good
only up to 30A, so I'll have to be careful). Also, can this be used for
secondary base current or would I need a high Fr current transformer? I
think this ones spec'd at 50 to 400 Hz.
Take care,

Bart

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Maintainer Paul Nicholson, paul@abelian.demon.co.uk.