My Cockroft-Walton Multiplier is not multiplying the voltage as projected

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Discussion Overview

The discussion revolves around the performance of a Cockcroft-Walton voltage multiplier circuit, specifically addressing issues with the output voltage not meeting expected projections when additional stages are added. The scope includes practical experimentation and troubleshooting of circuit components and configurations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • IntrepidElder reports achieving 260 V DC from the first stage of the circuit but only 312 V DC after adding a second stage, which is below the anticipated 480 V DC.
  • Participants inquire about the types of diodes and capacitors used, as well as the loading conditions on the output.
  • One participant suggests that certain capacitors may lose their ability to store charge if charged near half their voltage rating, potentially affecting circuit performance.
  • IntrepidElder confirms using 0.001µF 500V ceramic capacitors and 1N4004 diodes, noting that adding resistors in series resulted in a voltage drop.
  • There is a suggestion to include a large resistor in series for safety and to mitigate issues during experimentation.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the impact of capacitor types and loading conditions on the circuit's performance. No consensus is reached on the cause of the lower-than-expected output voltage.

Contextual Notes

Participants mention the importance of component ratings and configurations, but there are unresolved questions about the effects of loading and capacitor behavior under specific conditions.

Who May Find This Useful

Individuals interested in building or troubleshooting high-voltage circuits, particularly those involving voltage multipliers and related components.

intrepidelder
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Currently I have been messing around with relatively low voltage diodes and caps and arranging them in the specified order that has been found on the internet. My complication is this: My input is simply 120 V ac from a wall outlet. when connecting one stage ( one stage consisting of 2 Diodes and 2 Caps) the ouput voltage is 260 v dc. This is great! and exactly the result that I had anticipated. Following this I attatched one more stage, but my output voltage was only 312v dc. This isf ar below what is anticipated in the calculations. I should be receiving 480 vdc at the very least! I have exhausted all my resources and turn to anyone one who can aid me in my project.

I must clarifiy that the Caps I have are rated for 500 v and the diods are rated for 400 v, so the componet's limits are not being exceeded. I have arranged the diodes correctly so that they are facing the correct direction. For a refrence of the layout that i am using you can use this link as a reference: http://blazelabs.com/e-exp15.asp

I would greatly appreciate some help

-IntrepidElder
 
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What type of diodes are you using?

What is capacitance value (and voltage rating) of your caps?

What, if any, loading do you have on the output? (including the measurement circuit).

Do yourself a favor when playing around with a circuit like this and stick a relatively large resistor in series with the output (at least 300k while you're experimenting). And BE CAREFUL.
 
What kind of capacitors do you use? I think certain large types lose their ability to store charge(their capacitance goes down) if they are charged around half their voltage rating. I forget where I read this, but I thought it was for electrolytics. So if you are drawing a load from it, your effective source resistance will be much higher. Is the circuit unloaded?
 
The 4 caps are 0.001µF 500V 20% HI-Q Ceramic Disc Capacitor and the Diodes are 1N4004 Micro 1-amp Rectifier Diodes. I did put so resistors in series, but all that did was drop the voltage by two. I have no load yet, and am using a Voltmeter to ckeck the voltage that is all I have hooked up to it. so yes the current is unloaded.


-Intrepid Elder
 

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