Attension Walmart Shoppers-cheap hv supplies

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Attension Walmart Shoppers-cheap hv supplies

Post by guest » Thu Feb 07, 2002 4:40 pm

I really like Walmart.
I never seem to stop being amazed by rampant capitalism.
Guess what... strolling thru my neighborhood Walmart
Automotive section, I found a gem of high voltage practice on display in a plastic hang box.
Car neon displays.
They are true neon not a fake.
They come in colors like red , blue, purple and green.
It seems a popular movie ( Fast and Furious) caused the people at Walmart to carry these beauties as a stock item.
How much would you pay for a 12v , 7000 volt supply?
Would you pay 29.95 as the amazing1 people have been selling this stuff for?
How about 19.95?
For all day everyday the price is 9.95 with a 1 foot neon tube thrown in.
I imagine this will be a hot item but not what they planned for the end use of these things.
This makes it even cheaper to build demo fusors.
It addresses the portability issue fairly well also.

I have no clue yet about the amperage but will find out pretty soon.

Larry Leins
Physics Teacher & Cheapskate!


sweetRe: Attension Walmart Shoppers-cheap hv supplies

Post by guest » Thu Feb 07, 2002 5:21 pm

While low current is limiting somewhat Im gonna get me one-o-dem ASAP- thanks for the headsup!

Capacitors dont mind so much low current charging...

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Richard Hull
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Re: sweetRe: Attension Walmart Shoppers-cheap hv supplies

Post by Richard Hull » Thu Feb 07, 2002 5:40 pm

1 foot of neon would only need a few milliamps. It is important to remember that all neon runs at ~500 volts. It needs about 3 kv to start a short piece of neon (ionization breakdown) but all devices, even large and heavy neon sign transformers of 15kv, always dial themselves back to supply current and not voltage. The run voltage on a 15kv neon sign transformer is never over about 700 volts.

I would be stunned if these little devices supply over 2ma at over 3kv measured across the load. Demo fusors oten run at about 1.5kv @ 20ma or more, but need about 6 kv to start. This all assumes a vacuum of about 40 microns or better.

At 10 bucks its is worth a dabble just to see how they work.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.


Re: Attension Walmart Shoppers-cheap hv supplies

Post by guest » Thu Feb 07, 2002 6:49 pm

At the website

the following under high voltage

Air purification supplies.

1-7kv @ 4 ma 29.95
20kv @ 1 ma 19.95
1kv @ 4ma 9.95

Also 22kv diodes ,high voltage capacitors and resistors under general parts.

There seems to be movement on the cheap power front ... These are thumb sized ... run on 12volts.
An offshot from night vision I'd suspect.
Check out the light Saber (yes it exists as an expensive toy) industry while ya at it.

Larry Leins


Re: Attension Walmart Shoppers-cheap hv supplies

Post by guest » Thu Feb 07, 2002 9:20 pm

A very dangerous alternative is to bank microwave
oven transformers.
I'll bet you thought pulse charging would be difficult huh?
My pulse bank uses four microwave transformers in series output to make 8kv at .5 amps... I'm upgrading to an odd number to see if I can get 10 kv at .5 amp without burning down the house... This is very cheap but very dangrous ... killer. Diodes at 10 kv and .5 amp aren't cheap.... strings are out of the question. Tubes probably hold the key to rectifing this high current. Banked if necessary.

I have seen a banked diode rectifier that supports 125,000 volts at .5 amp. Easy to make, just take a bunch of diodes count them and divide the desired
voltage by the number of diodes. Make sure that you have a twenty percent or more safety margin on the rated voltage. The board must be a fiberglass resin boards like aircraft people use. (light green) Paper Phenolic just won't do. (brown boards.) (No perfing please!) I plan to use 2" pvc electrical pipe. Leave 1/2" to one inch of board from the diodes to the sides of the pipe. Two 2" caps finish the outer cover of the diode. A zigzag pattern connecting head to tail by a eached pattern on the back of the board. Diode separation should be in the neighborhood of .5 inchs at low voltages to 1 inch at the high voltages. No resisters in parrallel. What? In the old days the PIV ratings were very low on high voltage diodes. Not anymore. A 200 kev diode would be in the nieghborhood of 14 inches long.
Solder the hv lead to the first diode in the chain. Then bottom end cap is glued on with a hole to accomidate the high voltage lead. Fill the bottom assembly with molten wax, but dont touch the pc board! Use pipe glue to secure the body of the diode stack to the cap assembly . Solder a wire to the final diode in the stack.
drill a hole in the cap to accomidate the hv lead. Fill the pvc pipe with mineral oil. Put pvc glue on the cap. Slide the cap down the hv wire. Then put RTV calk on top around the wire. Allow the RTV to set before moving the diode stack. Go with the cheap diodes. You could put metal caps on each end so you could replace them easily. There are few limits on this stuff. If you have time and imagination the sky's the limit. I find that Russian diodes are real cheap now. Need 5 amps? Bank a gob of 500 volt diodes at 5 amps. Might take a very long tube. OK? People claim to have built voltage multipliers up to 5 MV. We will see.

So this leaves two options now for very high voltage supplies.

1. Use voltage multipliers to make the hv
2.. Use step up transformers with diode stack rectificaion at the end.

Must isolate the filements by stacking the rectifiers onto a pedestal and using batteries to run them or an isolated trani for filement supply. Wish I could find a kenotron these days.
An alternative is to use a salt water rectifier. When I was a kid, my first science project was an arc furnace made from a flower pot. My sixth grade science teacher had a hissy fit when I demonstated it. It was powered by plugging right in the wall. A mason jar of salt water rectified it to make 100 volts dc at 15 amps. Worked great ... pissed off safety nazis adults... Thank God I lived. Remote proceedure could do the same at higher voltage and lower amperage. Hydrogen Generation , hot water ect. Not for the faint of heart. I've had twenty years of hv tech from radar servicing. If you think I'm going to do this haphazardly
... think again. I' ve already had one near death experience... might not get off so lucky next time.
High Voltage screwup is the e-ticket to a mortuary.
Oh yeah ... If you don't want to trip breakers put a large
cap in front of your transformer setup.

Larry Leins
Physics Teacher


Re: Attension Walmart Shoppers-cheap hv supplies

Post by guest » Fri Feb 08, 2002 3:05 am

In reference to the expence of the HV diodes. THEY ARE CHEAP....if you know where to look. There are 10's of thousands of old MW ovens out there at repair shops just sitting around. The shops dont want them and they are difficult to dispose of. I have personally asked a dozen or so shops for parts out of their junked oven pile. They all said OK. As a result----FREE HV-High CURRENT diodes, MOT's, capacitors and other useful stuff.

Its a win-win relationship. Once you remove these items, the ovens become environment friendly and thus disposable.

However, I will point out one drawback to this type of parts procurement. MW Ovens are extremely dirty, greasy, cockroach infested items. Dirty work.

SAFETY NOTE: Im sure everyone here knows this, but for the silent lurkers out there----SAFELY DISCHARGE THE CAPACITOR BEFORE ATTEMPTING TO DISSECT ONE OF THESE !!!!!!! Not all of them have bleeder resistors.

Mark Rowley
Garage Scientist (unlicensed)


Re: Attension Walmart Shoppers-cheap hv supplies

Post by guest » Fri Feb 08, 2002 7:49 pm

I go round my father's house and find two to three
microwaves left on the curb. Some of them are still fuctional!
I dismantle them out of doors....
Don't get cut on one of these things!
You can take out the parts of several microwaves to make a usefull supply.
Ive sucessfully built voltage multipliers out of the caps and diodes from these ovens . ( it takes two microwaves to make a doubler. )
Snock's high voltage page or Joesten's High voltage page will show you how to build multipliers that will make up to 100kv.
All precautions apply for high voltage plus the fact the higher you go in voltage the more likely it might jump you to get to ground.
I like free.

Larry Leins
Physics Teacher

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