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Registered Member #1430
Joined: Sun Apr 06 2008, 11:12AM
Location: Ã…rhus, Denmark
Posts: 102
i just built a simple low voltage cockroft walton mutiplier and it's not working. im feeding it 7,8 volts AC. im using 2,2nF/100v capacitors and 1kv diodes. i did check the diodes and they are all the right way. im not getting ANY output. im using 4 diodes and 4 capacitors like in this photo:
Registered Member #1107
Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792
you are going to need to use caps in the uf range for it to work for 60 hz. In fact in atx psu's when you have it set for 120v operation in order to get the same voltage as 240v would be rectified they use a one stage cw multiplier and and those are the 2 big caps that is known to give you a nasty shock.
Registered Member #690
Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616
You can calculate the maximum power power output based on capacitance, frequency, and input voltage. I dont know the equation off the top of my head, but im sure wikipedia or google will have it.
At only 7,8 Volts you could use some large electrolytic capacitors, think in the thousands of microfarads. Thats really not much at at all in terms of size, i have 16V 2200uF capacitors that are the size of an AA battery.
well i done several CW so i hope i give you some advice :
better capacitance, the more current you can drive from it
the more stages, the longer needs to be charde all stages ( it is like when you have 100 HZ and 10 stages, you will be able to only draw max. when 10HZ, co better the freq. the better the result
caps can be any, but i was doing best with electrolythis, i also tried with foil 10n and it worked (but high frequency was used)
and you should get multimeter and try find 2 spots where the biggest woltage is - i think that from schematics it will be between upper right and down left spot.
Registered Member #1408
Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679
Solidacid wrote ...
i just built a simple low voltage cockroft walton mutiplier and it's not working. im feeding it 7,8 volts AC. im using 2,2nF/100v capacitors and 1kv diodes. i did check the diodes and they are all the right way. im not getting ANY output. im using 4 diodes and 4 capacitors like in this photo.....
any ideas what im might be doing wrong?
PERSONAL NOTE: Here is a great example of self study.....I had a very large amount of caps and was going to build this and that and they turned out to be the wrong caps (just like you). In my case when it was pointed out that the caps were wrong and that I could not get (let's say a MOT CAP or just substitute the wrong component) to do the job of another --- I studied what I could do with the stuff I had. You see, it's often not so much what you are DOING wrong but knowing what the materials are capable of doing!
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cockroft walton
