High Voltage & H2O

[diskus]

I have tried to mesure the HV on fluo driver
but my scope can't show more than 400V, and I don't want to fry the scope.
Do you have some sugestions about how to make a good HV scope probe?
         

[dracozny]

i dont recomend making one as accuracy goes out the window.
but all you need to do is attenuate the signal and that is done for the most part with a resistor at the correct watt rating so if your just measuring hv pulse dc then this should work fine. just use a little bit of ohms law to figure out the correct ohm rating you need.

[gyulasun]

Hi,

You may find the following link useful
http://www.eio.com/repairfaq/sam/hvprobe.htm

But there several other practical solutions on the web for building a HV probe if you google search for them.

regards

Gyula

[hartiberlin]

Just use a voltage divider with 2 resistors !
This will lower your input impedance on the scope, but
heck, you probablydon?t want to measure in the Mhz range, do you ?

[diskus]

Ok thank's
I will try to describe new electronics I made for fluo lamp

My setup was following:
Two  T-304 stainless steel tubes welded with T-304 wires for electrical contact
Dimension of :
      Inner tube
   Inner diameter = 23.0 mm
Outer diameter = 25.4 mm
Wall thickness = 1.22 mm
Height              = 101.67mm

     Outer tube
   Inner diameter =  30.78mm
   Outer diameter = 34.00mm
   Wall thickness = 1.47mm

Distance between Inner and Outer tube = 2.8mm
Capacitance in Air (dielectric constant=1) = 25.1 pF
Capacitance in Water (dielectric constant=80) = 2.01 nF

Water: Distillated water for use in medical purposes 

Electronics:
High Voltage Advanced generator- HVAG by A.de la Plaza
Output voltage >1000V  , you can see sparks on the picture Diskus_1
On output serially connected water capacitor with small fluorescent tube

I was changing the freq. and duty cycle but nothing was happening
The only thing was that the fluo.tube was lit up or shut down by varying those
parameters. The voltage on water condensatour always remaind the same.
I saw on scope that as I put a condensatour in the water the voltage instantly
droped to about 30V,and no charging effect took place.

Some suggestions ?

   Diskus