Voltage multiplier

John Larkin · 2011-09-25T18:22:33+00:00

I need a small, low-current, very low noise high voltage supply tobias an exotic and expensive photodiode, measuring the energy of a13.5 nm light source. I have +12 or maybe +15 to start with, and Iwant around +100 at less than a mA average. I looked at all theconventional approaches, flyback inverters and such, and didn't likethem much: too big, too noisy, custom magnetics, snubbers, loopstability issues, simulation, too much hard thinking.I was reminded of my previous concept, making a C-W multiplier chainusing switched SSRs instead of AC drive and diodes. Phil Hobbs,certainly in a spirit of friendliness and good cheer, called this ideathe Groucho Marx Generator.OK, how about this:ftp://This is the Harpo Marx Generator. A C-W/Groucho increases voltagelinearly with the number of stages. This one doubles voltage everystage, sort of like the octaves on a harp. The dual diodes would,ideally, be more SSRs, but the diodes are small and cheap and I cantolerate the drop here.Both Marx circuits can use big caps and switch at low frequencies, 500Hz maybe, so they will be very quiet. The caps can be biggish ceramicsor aluminums. Each SPDT switch is a dual SSR. If I do three stages and drive eachSSR control input from an FPGA pin - I have tons available - I cangate the clocks and select +24, +48, or +96 volts out, minus somediode drops. Good enough. Or build a hybrid, a true Marx BrothersCircuit, that does 24, 48, 72, or 96.John

Sep 25, 2011 109 Replies

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John Larkin 14 years ago

Silicon PN junctions! Here's one example.

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Some of these things have quantum efficiencies of 1000! Those xray photons pack a punch.

John

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John Larkin 14 years ago

We have a nice foot shear down in the machine shop, and an old crappy cheap rusty hand brake/shear thing in the corner. The good foot shear has a sign on it DO NOT USE FOR FR4 so I have to use the horrible old one.

John

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SoothSayer 14 years ago

Get a small bandsaw and a very fine pitch blade, and an upright belt sander with a nice, large, flat platen sitting next to it.

Absolutely smooth, straight finished edges,

Brakes and shears are for metal.

Glass is harder than steel. That is why a glass cutter does not actually make "a cut" in the glass, and why they dull. You can actually sharpen a knife with a big piece of FR4. I have some

0.3" x 1.25" x 6" 'sticks' of it, and it really works almost as good as a razor strap.

Dremel cut-off wheel works too (bigger is available), though considerations must be made to handle the particulate created.

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Jan Panteltje 14 years ago

On a sunny day (Fri, 30 Sep 2011 12:01:26 -0700) it happened John Larkin wrote in :

I thought you wanted 128 bit 100 cores?

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langwadt 14 years ago

lem.

ome

something like this works magic on fr4, not sure if you might be able to use water with fr4 to keep the dust down

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-Lasse

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Phil Hobbs 14 years ago

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Wow, that's intense. I have a set of aircraft shears with serrated blades that I've been cutting FR4 with for a decade. They still work fine, although not too many of my cuts are that straight. (Of course, in a dead bug prototype, wiggly cuts aren't usually the main aesthetic issue...)

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net

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krw 14 years ago

Never thought of that. I have a wet saw, though I don't very often cut FR4 at home. Yes, keeping the dust down is important. I'm sure your lungs would appreciate it. However, FR4 will pick up water.

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John Larkin 14 years ago

I occasionally grab a 12x12 sheet of copperclad FR4 and shear it up into an assortment of different sized squares, and keep them in a baggie in my office, for breadboarding. The shear is fast, quiet, clean, and makes beautiful cuts.

John

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John Larkin 14 years ago

How about this?

ftp://jjlarkin.lmi.net/Core_304bits.jpg

A 304 bit RAM.

John

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Jan Panteltje 14 years ago

On a sunny day (Mon, 03 Oct 2011 12:51:25 -0700) it happened John Larkin wrote in :

Why magnetic? This saves power:

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