[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Homemade Voltage Divider
Original poster: Yurtle Turtle <yurtle_t@xxxxxxxxx>
In that case, you could always calibrate your
home-made voltage divider with your HV probe. It
doesn't even matter if you're not linear, or off a
little, as long as you know where 10 kV is.
Adam
--- Tesla list <tesla@xxxxxxxxxx> wrote:
> Original poster: "David Rieben"
> <drieben@xxxxxxxxxxxxxxx>
>
> Hi Adam,
>
> Yes, I forgot that you also have some huge "quarter
> shrinking"
> caps yourself, so your applications of measurement
> would be relavent
> to my situation. Actually, I'm using a 240 volt to
> 30 kV bom-
> barder transformer that's only being fed up to 140
> volts in
> through a 120/140 volt variac. This allows for up to
> 15 to
> 17 kVAC output and I've constructed a FWB rectifier
> from
> HV diodes from an x-ray transformer to make it a 20
> kVDC
> power supply for cap charging. I've measured the
> full HVDC
> output from it with the variac maxed out and with a
> 50 kV,
> .025 µFd Maxwell across the HVDC output to filter it
> for measure-
> ment and got a 20 kV reading with my Beckman probe.
> Since
> the bombarder isn't current limited, I'll have to
> increase the
> voltage to charge the huge caps throught the variac
> slowly
> to insure that I don't short circuit the mains while
> charging,
> since I'm not using any ballasting in sereis with
> the bombar-
> der's input. Of course, reliable measurement of the
> terminal volt-
> age of the capacitor bank is crucial to insure that
> I don't
> overvolt the monsterous 440 to 450 uFd of caps at
> >10kV!
> I'm sure that internal dielectric flashover failure
> could result in
> disastorous external case rupture! I suppose that I
> could
> just take the Beckman probe apart and hardwire it to
> the
> shrinking circuit as you've done, but that would
> render my
> Beckman probe unusable for making any other HV
> measure-
> ments outside of the shrinker circuit. That's reason
> I'm consi-
> dering building the "homemade" voltage divider.
>
> David Rieben
>
>
> ----- Original Message ----- From: "Tesla list"
> <tesla@xxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Tuesday, January 24, 2006 9:22 AM
> Subject: Re: Homemade Voltage Divider
>
>
> Original poster: Yurtle Turtle <yurtle_t@xxxxxxxxx>
>
> What kind of PSU do you have? I have this one:
>
> http://hot-streamer.com/adam/garage/psu_34kV_1.jpg
> http://hot-streamer.com/adam/garage/psu_34kV_2.jpg
>
> and built this controller from an old VTVM:
>
> http://hot-streamer.com/adam/garage/psu_34kV_3.jpg
>
> My PSU outputs a voltage, 0 - 5 volts I believe,
> relative to output. For calibration, I used a
> Maxwell
> 30nf 35kV cap and cranked it up until I hit my
> target,
> which was 10 kV. I simply used the VTVM gauge and a
> pot to fine tune it to match my DMM and HV probe.
> Although I have used it as a handheld, my HV probe
> cane with a removance tip, allowing me to hardwire
> it
> to the circuit I'm measuring. I disconnect my PSU
> from
> the shrinking circuit before firing it.
>
> Adam
>
> --- Tesla list <tesla@xxxxxxxxxx> wrote:
>
> > Original poster: "David Rieben"
> > <drieben@xxxxxxxxxxxxxxx>
> >
> > Hi all,
> >
> > I am pondering a way to reliably measure 10 KVDC
> > across the terminals of (2) 100 µFd energy dis-
> > charge caps that I plan to build a quarter
> shrinker/
> > can crusher project with. I will have up to a
> total
> > of 450 µFd at 10 kV when I get 2 other 120
> > µFd, 10 kV caps added to my collection. Anyway,
> > I was originally going to just use my Beckman HV
> > probe in combo with one of my DVMs to monitor
> > the voltage at the cap terminals to insure that I
> > do not overvolt the caps, since my HVDC supply
> > can go up to about 20 kVDC. However, I believe
> > the HV probe isn't desinged to be used like this
> > as its ergonomics lends it for hand held
> operation
> > so I was thinking of getting some 10K or 100K
> > carbon resistors and building a 100 resistor di-
> > vider to get a 100:1 reduction to safely
> > read 10 kV on my DVM as 100 volts. What
> > are the best resistance values to go for 10 K
> > or 100 K? A 1 Meg total with 10K(X100) would
> > still allow 10 mA of current flow at 10 kV and
> that
> > would translate to 100 watts (WOW)! I suppose
> > that I just answered my own question- don't think
> > (100) 1/4 resistors would take much of that!
> Better
> > go
> > for 100 K per resistor, that would only allow up
> to
> > 1 mA
> > of current flow at 10 kV and 10 watts. I believe
> 10
> > watts spread over (100) 1/4 watt resistors would
> > work ;^)
> > Any comments or suggestions?
> >
> > David Rieben
> >
> >
> >
>
>
>