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I need some help.. (with voltage multiplier)

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chek

Thu Mar 06 2008, 09:07AM

Registered Member #1373 Joined: Tue Mar 04 2008, 12:45PM
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Posts: 20

what else i need to do for safety reason??anyway...thanks for the info..

chek

Tue Mar 11 2008, 05:01AM

Registered Member #1373 Joined: Tue Mar 04 2008, 12:45PM
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Posts: 20

can someone explain why there are two type of formula in calculating the stage of CW??
some formula state that only the value of voltage are calculated but some say the voltage that being calculated must be in RMS value...

Mates

Tue Mar 11 2008, 07:16AM

Registered Member #1025 Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566

each stage in the multiplier should be able to stand double the RMS voltage in case of a symetric AC power supply...So it means in case you use 220V AC (from the wall plug-in) than every stage should be minimum 700V DC rated.

Sulaiman

Tue Mar 11 2008, 04:57PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

Should be 2 x Vpk-pk = 2 x SQRT(2) x Vac voltage rating per stage,
which for 220Vac is 622.25 V
Don't forget that Europe has 'harmonised' the supply to 230 Vac nominal.
- but due to spikes/surges etc. 1000V rating per stage is required.

Proud Mary

Tue Mar 11 2008, 07:22PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

For reliable calculation of component values in a C&W multiplier, we must first specify Vout, Iout, the number of stages n, the operating frequency f, the percentage of voltage regulation required at the output , and the the acceptable output ripple voltage, Vrip.

Without these parameters, any calculation of values will be unreliable.

chek

Wed Mar 12 2008, 01:29PM

Registered Member #1373 Joined: Tue Mar 04 2008, 12:45PM
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ok..i got it..there some question about selecting the capacitor..what is the main character need to be considered?

Proud Mary

Wed Mar 12 2008, 03:23PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Performance specifications for high voltage capacitors include capacitance range and capacitance tolerance, a percentage of total capacitance. Working DC voltage, insulation resistance, dissipation factor, and temperature coefficient are additional considerations. Working DC voltage (WVDC) is the maximum voltage that can be applied continuously at any temperature between a lower category temperature and the rated temperature. Insulation resistance is the ratio between an applied DC voltage and the resulting leakage current. The dissipation factor (DF) is the ratio between the resistive and reactive parts of a capacitorâ€™s impedance when a sinusoidal voltage at a specified frequency is applied. The temperature coefficient is the change in capacitance measured over a range of temperatures.

The capacitors in large laboratory C&W PSUs are often custom made, but much of the art of the amateur is in pressing existing components into a service for which they weren't originally intended, or pushing them beyond the manufacturer's voltage ratings and seeing how far they will go before breaking down.

I am a rather conservative constructor, so if my proposed stage voltage was 10kV, I would choose 25kV capacitors, but many here will run capacitors actually at or even a bit over their voltage ratings and often have just as good results, especially when the apparatus is not to be left running continuously for long periods of time.

High voltage capacitors are nearly always disproportionately expensive (as not many of them are manufactured) so you will find no end of examples on this forum of blokes stringing capacitors together in series-parallel arrangements to make a single capacitor of the capacitance and voltage rating they need.

chek

Thu Mar 13 2008, 09:20AM

Registered Member #1373 Joined: Tue Mar 04 2008, 12:45PM
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Posts: 20

thanks..i'm sorry for asking so many question...this is my 1st HV project n i really don't have any idea about it..any recommendation about simulation program that should i use to simulate this project??

chek

Wed Mar 26 2008, 07:07AM

Registered Member #1373 Joined: Tue Mar 04 2008, 12:45PM
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Posts: 20

anybody..can this project give out spark and what i need to do if i want to make the spark??
please..anybody..

chek

Sat Apr 05 2008, 04:58AM

Registered Member #1373 Joined: Tue Mar 04 2008, 12:45PM
Location:
Posts: 20

hi everyone...i have construct the 10kV-CW multiplier with input resistor value of 10kohm..but when i turn ON the circuit, the resistor burned and finally blown..can any body give opinion, what should i do?? i really need to finish this project....

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