Cockroft-Walton generator
Bookmark this page:
 Yahoo!
 Google
 Windows Live
 del.icio.us
 digg
 Netscape
|
|
||||||||||||||||||||||||||||||||||
|
Posted by cloudguitar on May 24, 2008, 2:14 pm
Please log in for more thread options I am trying to build a simple half-wave CW generator (aka Villard cascade) for my Physics class. At the moment, I have 4 stages composed of 1.5 nF capacitors (rated for 2kV) and diodes with an internal resistance of 500ohm, connected to a 12V 50 Hz AC supply. I simulated the circuit with Qucs and, as I was expecting from calculations, the no-load output would have been around 100V DC. What happens is that my multimeter reads 2.5V DC, instead. I suspect I am doing something wrong with voltage probing. Referring to this circuit schema: http://upload.wikimedia.org/wikipedia/en/4/4c/Cockcroft_Walton_Voltage_multiplier.png I connected the red probe to the output of the last stage (the circle in the image) and the black probe to where the ground should be in the schema. The circuit is open, and the voltmeter should close it by connecting the last stage to the generator - also, there is no connection with the AC supply ground. Unfortunately, I am a newbie and I cannot figure out what is happening. Any idea? Thank you very much for your time, Claudio A. | ||||||||||||||||||||||||||||||||||
|
Posted by Jamie on May 24, 2008, 2:32 pm
Please log in for more thread options > I connected the red probe to the output of the last stage (the circle
Is your meter a 10 meg ohm input type ?
> in the image) and the black probe to where the ground should be in the > schema. The circuit is open, and the voltmeter should close it by > connecting the last stage to the generator - also, there is no > connection with the AC supply ground. > > Unfortunately, I am a newbie and I cannot figure out what is > happening. > Any idea? > > Thank you very much for your time, > > Claudio A. > also, 1.5 nf is small for 50 hz. you may want to try larger caps.. Also, you don't need 2kv caps at the voltage you're starting at. http://webpages.charter.net/jamie_5" | ||||||||||||||||||||||||||||||||||
|
Posted by cloudguitar on May 24, 2008, 2:34 pm
Please log in for more thread options On May 24, 8:32 pm, Jamie
> cloudguitar wrote:
> > Hi all,
>
> > I am trying to build a simple half-wave CW generator (aka Villard
> > cascade) for my Physics class. >
> > At the moment, I have 4 stages composed of 1.5 nF capacitors (rated
> > for 2kV) and diodes with an internal resistance of 500ohm, connected > > to a 12V 50 Hz AC supply. >
> > I simulated the circuit with Qucs and, as I was expecting from
> > calculations, the no-load output would have been around 100V DC. What > > happens is that my multimeter reads 2.5V DC, instead. >
> > I suspect I am doing something wrong with voltage probing. Referring
> > to this circuit schema: > >http://upload.wikimedia.org/wikipedia/en/4/4c/Cockcroft_Walton_Voltag... > > I connected the red probe to the output of the last stage (the circle > > in the image) and the black probe to where the ground should be in the > > schema. The circuit is open, and the voltmeter should close it by > > connecting the last stage to the generator - also, there is no > > connection with the AC supply ground. >
> > Unfortunately, I am a newbie and I cannot figure out what is
> > happening. > > Any idea? >
> > Thank you very much for your time,
>
> > Claudio A.
>
> Is your meter a 10 meg ohm input type ? > also, 1.5 nf is small for 50 hz. you may want to > try larger caps.. > Also, you don't need 2kv caps at the voltage you're > starting at. > > http://webpages.charter.net/jamie_5" Thanks for your reply. yes, my meter is a 10MOhm multimeter. I was planning to add 4 stages (reaching 8 stages) and to switch to a 230V 50Hz supply, so 2kV should be barely enough. Do you think that I should try with 230V right now? I also have 15nF @ 3kV caps, do you think the would be better suited? | ||||||||||||||||||||||||||||||||||
|
Posted by Jamie on May 24, 2008, 2:53 pm
Please log in for more thread options cloudguitar wrote:
> On May 24, 8:32 pm, Jamie
> >>cloudguitar wrote:
>> >>>Hi all,
>>
>>>I am trying to build a simple half-wave CW generator (aka Villard
>>>cascade) for my Physics class. >>
>>>At the moment, I have 4 stages composed of 1.5 nF capacitors (rated
>>>for 2kV) and diodes with an internal resistance of 500ohm, connected >>>to a 12V 50 Hz AC supply. >>
>>>I simulated the circuit with Qucs and, as I was expecting from
>>>calculations, the no-load output would have been around 100V DC. What >>>happens is that my multimeter reads 2.5V DC, instead. >>
>>>I suspect I am doing something wrong with voltage probing. Referring
>>>to this circuit schema: >>>http://upload.wikimedia.org/wikipedia/en/4/4c/Cockcroft_Walton_Voltag... >>>I connected the red probe to the output of the last stage (the circle >>>in the image) and the black probe to where the ground should be in the >>>schema. The circuit is open, and the voltmeter should close it by >>>connecting the last stage to the generator - also, there is no >>>connection with the AC supply ground. >>
>>>Unfortunately, I am a newbie and I cannot figure out what is
>>>happening. >>>Any idea? >>
>>>Thank you very much for your time,
>>
>>> Claudio A.
>>
>> Is your meter a 10 meg ohm input type ? >>also, 1.5 nf is small for 50 hz. you may want to >>try larger caps.. >> Also, you don't need 2kv caps at the voltage you're >>starting at. >> >>http://webpages.charter.net/jamie_5" >
I would try the larger caps first.
> > Thanks for your reply. > > yes, my meter is a 10MOhm multimeter. I was planning to add 4 stages > (reaching 8 stages) and to switch to a 230V 50Hz supply, so 2kV should > be barely enough. > Do you think that I should try with 230V right now? > > I also have 15nF @ 3kV caps, do you think the would be better suited? -- "I'd rather have a bottle in front of me than a frontal lobotomy" http://webpages.charter.net/jamie_5" | ||||||||||||||||||||||||||||||||||
|
Posted by Paul E. Schoen on May 24, 2008, 3:58 pm
Please log in for more thread options
> cloudguitar wrote:
> >> On May 24, 8:32 pm, Jamie
>> >>>cloudguitar wrote:
>>> >>>>Hi all, >>> >>>>I am trying to build a simple half-wave CW generator (aka Villard >>>>cascade) for my Physics class. >>> >>>>At the moment, I have 4 stages composed of 1.5 nF capacitors (rated >>>>for 2kV) and diodes with an internal resistance of 500ohm, connected >>>>to a 12V 50 Hz AC supply. >>> >>>>I simulated the circuit with Qucs and, as I was expecting from >>>>calculations, the no-load output would have been around 100V DC. What >>>>happens is that my multimeter reads 2.5V DC, instead. >>> >>>>I suspect I am doing something wrong with voltage probing. Referring >>>>to this circuit schema: >>>>http://upload.wikimedia.org/wikipedia/en/4/4c/Cockcroft_Walton_Voltag... >>>>I connected the red probe to the output of the last stage (the circle >>>>in the image) and the black probe to where the ground should be in the >>>>schema. The circuit is open, and the voltmeter should close it by >>>>connecting the last stage to the generator - also, there is no >>>>connection with the AC supply ground. >>> >>>>Unfortunately, I am a newbie and I cannot figure out what is >>>>happening. >>>>Any idea? >>> >>>>Thank you very much for your time, >>> >>>> Claudio A. >>> >>> Is your meter a 10 meg ohm input type ? >>>also, 1.5 nf is small for 50 hz. you may want to >>>try larger caps.. >>> Also, you don't need 2kv caps at the voltage you're >>>starting at. >>> >>>http://webpages.charter.net/jamie_5" >>
>> >> Thanks for your reply. >> >> yes, my meter is a 10MOhm multimeter. I was planning to add 4 stages >> (reaching 8 stages) and to switch to a 230V 50Hz supply, so 2kV should >> be barely enough. >> Do you think that I should try with 230V right now? >> >> I also have 15nF @ 3kV caps, do you think the would be better suited? > I would try the larger caps first.
Also, check the forward voltage drop of your diodes. The 500 ohm resistance figure you give does not make sense. Maybe you mean 500 mV at 1 mA, but if you have high voltage diodes they may be several junctions in series, which would explain a low output with 12 VAC. Paul | ||||||||||||||||||||||||||||||||||
| Similar Threads | Posted |
| generator | November 25, 2005, 2:44 pm |
| Generator for LEDs | October 19, 2005, 11:56 pm |
| Motor generator | October 23, 2005, 5:09 am |
| Tracking Generator | November 27, 2005, 10:33 am |
| Audio Generator | February 4, 2006, 8:34 am |
| Generator characteristics | June 21, 2006, 4:19 am |
| using a motor as a generator | July 21, 2006, 5:38 pm |
| waveform generator | August 19, 2006, 1:37 pm |
| Funciton Generator | December 6, 2007, 7:20 am |
| PC Audio Generator | September 4, 2008, 7:17 am |
| More on dual pulse generator | December 5, 2004, 1:49 am |
| Need a circuit! Sinewave Generator | December 26, 2004, 7:17 am |
| Low voltage Marx generator? | May 3, 2005, 10:08 pm |
| How does a wind-up generator work? | June 10, 2005, 2:40 pm |
| clock generator and synthesizer | August 2, 2005, 8:52 pm |
>
> I am trying to build a simple half-wave CW generator (aka Villard
> cascade) for my Physics class.
>
> At the moment, I have 4 stages composed of 1.5 nF capacitors (rated
> for 2kV) and diodes with an internal resistance of 500ohm, connected
> to a 12V 50 Hz AC supply.
>
> I simulated the circuit with Qucs and, as I was expecting from
> calculations, the no-load output would have been around 100V DC. What
> happens is that my multimeter reads 2.5V DC, instead.
>
> I suspect I am doing something wrong with voltage probing. Referring
> to this circuit schema:
>