ins_atge@jhunix.HCF.JHU.EDU (Thomas G Edwards) (08/07/90)
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, making the laser useless
for light shows. I think if I can reduce the voltage comming out of
my set-up transformer, I can get rid of the pre-step-up transformers
feeding it, and increase the amount of current going into the circuit
so hopefully the nasty ripple on the output will decrease.
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?
2) How can I reduce ripple and/or assure more avaliable current
from above circuit?
-Thomas
ins_atge@jhunix.hcf.jhu.eduvekurpan@tekred.CNA.TEK.COM (Vincent E Kurpan) (08/07/90)
Voltage multipliers: Voltage multipliers can be made for n times peak with certain practical restraints like load current. Various handbooks cary the formulas. I recommend testing at low voltage first and measuring all voltages first. If you can not find it in any books send your mailing address and I will run a copy.
whit@milton.u.washington.edu (John Whitmore) (08/08/90)
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.
ins_atge@jhunix.HCF.JHU.EDU (Thomas G Edwards) (08/09/90)
In article <6024@milton.u.washington.edu> whit@milton.u.washington.edu (John Whitmore) writes: > 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. I have built one of these...at 60Hz feed it doesn't provide enough current to get the laser fired up. However, my voltage quadrupler with four capacitors was...it wasn't set up like Cockroft-Walton. I might go the C-W route though with a higher frequency input, but I'd still like to find non C-W *5 and *6 voltage circuits. (If you don't run a HeNe tube with D.C., won't the flicker be horrible? Besides,tubes have cathodes and anodes, and it reacts very badly if you try to reverse-bias it (but it can lase, just at higher voltages) Thanks, -Tom