Re: Homemade Voltage Divider

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Yurtle Turtle <yurtle_t@xxxxxxxxx>

I used to use my 15/120:

http://www.hot-streamer.com/adam/garage/NST_15-120a.jpg

with a set of x-ray diodes:

http://www.hot-streamer.com/adam/garage/diodes_125_kV_1_amp_1.jpg

http://www.hot-streamer.com/adam/garage/diodes_125_kV_1_amp_2.jpg

to charge up mine. I simply used my DMM with a HV
probe to measure cap voltage, and a variac to control
the voltage. Once I was charged, I disconnected the
DMM and the PSU and fired it. I found that if I ramp
up the voltage pretty fast then turn it down as I get
close to your target voltage, I could get pretty
close. Since my NST is current limited, you may have
to slowly ramp up your bombarder. You can always put
an amp clamp on the bombarder LV side, just to see
what's going on.

Adam

--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: "David Rieben"
> <drieben@xxxxxxxxxxxxxxx>
>
> Dr, all,
>
> Yes, this is true, but when you're measuring the
> voltage of a charging capacitor bank at the
> capacitors' terminals while charging the caps
> up, the measured voltage will be considerably
> lower than the applied voltage until the caps'
> charge voltage reaches equalibrium with the
> charging supply voltage. This is due to the
> heavy load that the caps place upon the power
> supply while charging and also the reason that
> the power supply's voltage must reach higher than
> the desired charge voltage of the caps. Otherwise
> it would take an excessive period of time to fully
> charge the caps if the maximum available supply
> voltage was only about equal to the max charge
> voltage of the caps. Since the power supply's
> voltage must reach higher than the caps' rated
> voltage, the measured DC voltage at the capacitors'
> terminals must be measured and the power supply
> immediately shut off when the voltage at the caps'
> terminals reaches their rated voltage to prevent
> over-
> volting of the caps, thus my reason for measuring
> the
> DC voltage at the caps' terminals.
>
> Also, I was wanting to know if I would need some
> type of HV resistor in series with the HV DC input
> to the caps since the bombarder transformer supply
> isn't current limited? I would gradually ramp up the
> voltage input to the bombarder with a variac while
> monitoring the voltage at the caps' terminals but
> the
> bombarder can act almost like a dead short while
> charging >400 µFd of capacitor towards 10 kV
> until the capacitors' charge gets close to the
> applied
> voltage. I have a ~250 watt, 3 kOhm resistor that I
> could use. Would this be about the right size and
> resistance for this purpose?
>
> Thanks,
> David Rieben
>
>
>
> ----- Original Message ----- From: "Tesla list"
> <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Tuesday, January 31, 2006 10:35 PM
> Subject: Re: Homemade Voltage Divider
>
>
> Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>
>
>
> You never need to measure the DC voltage.  It's
> always 1.414 x the Erms, so you are actually
> measuring Erms and then just recalibrating the
> meter face to reflect the actual measured DC
> potential.  No messing around with HV resistors,
> etc.
>
> Dr. Resonance
>
>
>
> When I mentioned the NST method I was thinking he
> wanted to measure the AC input to the DC filter -
> didn't engage brain. Transformers don't work well at
> DC.
> Jim
> ----- Original Message -----
> From: <mailto:tesla@xxxxxxxxxx>Tesla list
> To: <mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx
> Sent: Saturday, January 28, 2006 12:00 PM
> Subject: Re: Homemade Voltage Divider
>
> Original poster: Yurtle Turtle
> <<mailto:yurtle_t@xxxxxxxxx>yurtle_t@xxxxxxxxx>
>
> An NST will work for AC, but not DC.
>
> Adam
>
> --- Tesla list
> <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> wrote:
>
>   > Original poster: "James Zimmerschied"
>   > <<mailto:zimtesla@xxxxxxx>zimtesla@xxxxxxx>
>   >
>   > I am pondering a way to reliably measure 10 KVDC
>   > across the terminals of (2) 100 µFd energy dis-
>   > charge caps Original poster: "David Rieben"
>   >
>   > David
>   > Richard Hull showed the use of a NST is reverse
>   > to measure high voltages. This might be bulky
> but
>   > reliable.
>   > Jim Zimmerschied
>   >
>   >
>   >
>
>
>
>
>
>
>
>
>


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