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# Can you charge (safely) a 450V Capacitor by using a voltage multiplyer/dobler on mains (240V RMS)? Answered

I'm looking at building a coilgun and wondering if you could charge my caps via a voltage dobler on mains. Also is ther a formula for calculating the output of a voltage multiplyer?
Thanks a bunch,
Mike

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Yes! But rectify the alternating current before it goes into the caps sothat you don't have the wrong polarity going in and blowing shrapnel atyour valuable optic sensory input organs.<br />You might be able to scrounge a bridge rectifier out of any wall wart,except you'll want to find one that rectifies the AC <em>before</em> it goes into any sort of voltage drop (otherwise the rectifier probablywon't hold up against the high voltage, being at a lower rating).<br />Recap: get a bridge rectifier, or build one, that is rated at the 450volts you plan to work with. Search <a href="http://www.digikey.com">Digikey</a> for it.<br />

Use a transformer that steps up voltage 1:2 so you turn your 240 into 480. Then rectify it with a bridge rectifier rated at 500 volts. You'll get the RMS voltage out of it, which I'm not sure how to calculate. But your capacitors will eat it up! Yum yum yum.

RMS is peak to peak times .707.

Peak to peak? In this case what does that turn out to be?

500 x .707 = 353.5<br />

So if it peaked at 480 (as our friend will see), it will end up looking like 339.36v?

Something like that.

I would look at coilguns people have made and do it that way. Having ideas about playing with mains electricity without really knowing what to do sounds a bit dangerous.<br />Try reading here (for one of many)<br /><a href="http://www.anothercoilgunsite.com/">www.anothercoilgunsite.com/</a><br /><br />L<br />