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From: whit@milton.u.washington.edu (John Whitmore)
Newsgroups: sci.electronics
Subject: Re: Voltage quintupler/sextupler
Message-ID: <6024@milton.u.washington.edu>
Date: 8 Aug 90 03:04:55 GMT
References: <6035@jhunix.HCF.JHU.EDU>
Organization: University of Washington, Seattle
Lines: 40

In article <6035@jhunix.HCF.JHU.EDU> ins_atge@jhunix.UUCP (Thomas G Edwards) writes:
>I am working on revamping my laser power supply.  I have to
>significantly over-voltage my step-up transformer to provide the
>voltage required by my voltage quadrupler circuit.
>I also get massive ripple on the output...
>
>So here are two questions:
>1)  I have seen plenty of plans for a voltage quadrupler.  How can I
>    make a voltage quintupler or sextupler?  Is there some "formula"
>    which can be iterated to make a times-N voltage circuit? 


	Yes; these multipliers are a Cockroft-Walton circuit
and consist of N diodes, all series-connected (pointed in the same
direction), with a capacitor from node 0 to 2, one from node 1 to
3, one from node 2 to 4, one from node 3 to 5, et cetera.
	One grounds node 0, and drives (through a capacitor)
node 1; node N achieves peak voltages of circa N times the
drive voltage.
>
>2)  How can I reduce ripple and/or assure more avaliable current
>    from above circuit?

	I infer from your posting that you are using a 60 Hz
source to drive all this; use instead a higher frequency
oscillator (15-35 kHz), and you will get larger currents from
the same capacitors (in the doubler/tripler/multiplier circuit).
Since all TVs use this scheme, you might just purchase a TV
repair part HV multiplier (at REALLY high voltages, a potted
module is the only safe and convenient way to handle the
high-voltage end of the circuit).  
	If there's a switching power supply handy (VERY low power
recommended here!) you can tap into its transformer's primary
for a convenient oscillator with more than adequate power output.

	Are you sure you really want DC to drive your laser?  Won't
this cause shortened tube lifetime due to electrode erosion?

I am known for my brilliance,               John Whitmore
 by those who do not know me well.