Build a Variable High Voltage Power Supply

I needed a variable 0 to 50KV high voltage power supply for my high voltage experiments that wouldn't break the bank, so I built my own.

With just a few parts from old microwave ovens, TV sets, and an oil burner, you can build an affordable instrument for whatever you wish to snap,crackle, or pop!

The key component is the voltage multiplier, which I covered in the High Voltage Multiplier instructable. Build it first, then drop it into this project for a variable output.

Step 1: Theory of Operation

The diagram shows the supply in the de-energized condition and the case closed.

Mains voltage is applied to the power supply thru a 120 VAC Panel connector. With the case closed, current passes through a 5 Amp fuse, F1 and through the case safety switch, S1 causing the Ready indicator, I1 to light when the power switch S2 is placed in the ON position to energize the supply.

At this time, the power supply is NOT ON but in a state of readiness to enegize the high voltage stage.

When pushbutton S3 is pressed, relay K1 energizes and remains energized after S3 is released.

Current passes through Variac, VT1 which adjusts the input voltage to the OBT. The OBT steps up the input voltage to a maximum of 6,000 VAC. The output of the OBT is fed to the high voltage multiplier, HVM where it is multiplied to 51,000 VDC output.

To de-energize the supply, place S2 in the OFF position. K1 will de-energize and remove power from the OBT and HVM and all indicators will extinguish.

The case safety switch and the power contactor are not necessary for this supply to work. I thought the ability to power on and off by using a pushbutton was cool. Thats all. The second schematic shows them removed.

Comments

[jpayton]

What is the output current of this?

[RetiredResearchEngineer]

My load has very high impedance so I need virtually no current (<< 1 mA) but I would like to reduce the ripple on the output so it is negligible.  A simple RC low-pass filter with a resistor and a capacitor in series across the original output should do the trick. I don't want to have to find a 100 kV cap so I'll just join a few 20 kV caps in series to create a cap unit that will handle the voltage. My new + output will come from the junction of the resistor and the + end of the caps (the low-pass filter output).

Member Machine mentioned earlier that a front panel meter would be nice and I agree. He had some concerns about using a voltage divider so the meter could work with some reasonable voltage like 0 to 10 V instead of 0 to 50 kV. I've done the resistor voltage divider thing successfully at 50 kV using a 5000:1 voltage divider. I then connected the divided voltage output to an analog DC voltmeter calibrated to 0 - 10 V.

One final comment.  I plan to use a 3PDT relay for K1 so the third pole can be used to discharge the HV output through an appropriately sized current limiting resistor.  I plan to connect the HV output to one end of the resistor and the other end of the resistor to the common of the third pole on K1.  The NC contact of the third pole goes to ground.  Whenever K1 is not energized, the HV output is routed to ground through the current limiting resistor.

Do you see any problems with any of the above enhancement assuming I use appropriately rated components and good HV insulation practice?

[corbonzo]

Sorry if this is a stupid thing to ask.but i dont have money for a variac, i was wondering if a 120vac light dimmer used in houses would work. it says rated for 600 watts which would mean 5 amps right? sooo would that work? a reply would be great!

[prini]

oh ok thank you for answering me,alls i needed was a power supply that could power a minimum of 400 amps

[burningsuntech]

NOTICE
This device is for sale. If you would like further details, please contact me at [e-mail]
- BST

[prini]

is this really strong ? would this say power a house? im looking for a very strong power supply for somthing im building wich requires as much power as a house maybe more lol

[burningsuntech]

prini
This is a HIGH VOLTAGE power supply and cannot be used to power a house which is low voltage (120 volts AC). This is also a low current supply (20 milliamps) and a house requires high current (200 Amps). So, no. This will not suit your needs.
-BST

[garagegenius]

Hey, I'm looking for something on the scale of 50kv 10 milliamps. would i be able to adjust or modify this to get 10 milliamps? any help would be appreciated

[luismasino]

Hi, I am needing to build a project of the variable power source 0-40kV can walk, I need if I you can send information to build the source as you did, since I can not download the pdf, you made me the source would come very well. please if you can send me information on the value of the component and the names and designing things. any information will be very welcome
thank you very much

[Machine]

I like the quality internal layout, it looks professionally done. A meter on the front panel could be good.

It'd be hard to measure directly the output volts as a high-voltage divider would be needed (more cost, insulation difficulties).

So a meter calibrated in kV but measuring the output volts at VT1 would be an easier method to indicate final voltage.

[wespow1]

i cant seem to get the image up so i'll give you a URL to the burner http://www.ebay.com/itm/OIL-BURNER-TRANSFORMER-110-HIGH-VOLTAGE-10-000-WEIL-MCLAIN-GOLD-BURNER-BASE-NEW-/120811839341?pt=LH_DefaultDomain_0&hash=item1c20f25f6d#ht_1543wt_1163

[wespow1]

Hello i was wondering if a OIL BURNER TRANSFORMER 110 HIGH VOLTAGE 10,000 WEIL MCLAIN GOLD BURNER BASE NEW would work here is a images of the burner

[votedthewave]

Is this -50kv or +50kv?

[Electronics111]

+50kv i think

[jmaniglia]

If you connect the leads reverse it will be -50 as well

[janderja]

Yes it will be -50 wrt the other lead but not -50 wrt earth ground.

How can you make it -50 wrt earth ground? This will allow it to be used as a negative ion generator.

[weldor]

I have a sneaking suspicion that this could be turned into some sort of a welding device (TIG or Spot). Possibly a device that was both CC and CV capable. Possibly ac/dc with cc/cv for the TIG and some sort of variable control for the spot welder too. all of the above could be assembled in one unit.

Automatic trans fluid is supposed to work well and it has an operating temp of well over 100 deg F.

An aluminum housing with heat sink fins (or even tubes) with air being circulated over/ through them. H2O running through external copper tubes and then into a heat exchanger (auto heater core or ac condenser) would improve your coolin effect also. This could lead to more efficient over all operation. (water cooled TIG torch??)

Great Instructable!!!! please keep it up.

[ifrit]

will there be enuff power in this powerbox to serge my invisability cloak and will there be enuff power in this box to channel me for teleport and download me at any power source ?

[infinity11]

Is this a positive currant you are producing and if it is how could I make it negative.

[aweis]

if i only want a killavolt (1000 volts) from a 70 volt alternating current generator, would i be able to do that for around 50 dollars?

[burningsuntech]

Aweis,
Possibly. As to specifics, I can't say. Most likely, you will be using 1N4007 diodes for the diodes. And caps will be .001ufd 2 KV minimum, but any voltage up to 10Kv will be fine.

There has been a lot of questions concerning the math I used to figure out the voltages. So I will refer you to the link that I found concerning Cockroft-Walton Voltage Multipliers.


http://en.wikipedia.org/wiki/Cockcroft%E2%80%93Walton_generator


And here is a blurb about the output voltage characteristics of the multiplier:

http://www.allaboutcircuits.com/vol_3/chpt_3/8.html


Good luck in your build.

RA

[Moo_cow]

If I were to take out the multiplier, would if work for 0-6000 volts?
Wanting to use this for part of my science fair but I do not need to go over 6000 volts.

[burningsuntech]

Moo_cow

If you only want 0 to 6000 volts AC, then the answer is yes.

If you need 0 to 6000 volts DC, then you must add a single 12KV Diode to the output of the transformer.

Good Luck in the science fair.

RA

[ewpwrqlty]

I only need a 100-700 VAC variable supply. Can I modify your design to achieve this goal?

[burningsuntech]

Possibly.

without knowing details like how much current you want the device to provide and at what voltages, I wont be able to help.

More info is needed besides "can I modify your design to achieve this goal?"

RA

[ewpwrqlty]

Thanks for your quick response.

The device does not need to provide any current. I only need to provide variable voltage potentials between 100-700 VAC. I am attempting to create a voltage calibration set for my BMI 8800 power disturbance analyzers.

The required voltage (Vrms) calibration levels are:

1. 0
2. 7.6-8.4
3. 30.2-33.4
4. 75.5-83.5
5. 150-170
6. 200-225
7. 300-335
8. 604-670

I am using a 0-140VAC Variac to produce the first four levels.

I tried using a hipot tester to produce the last four levels and was successful up to level 8. The hipot unit that I own is a Hiptronics HD5 0-5KV at 5 mA.
The impedance of the BMI voltage input channels during calibration is 1.01 Megga Ohm. At approximately 500 VAC the leakage current light was glowing and the unit was vibrating and ready to fail on leakage. My Hipot tester would need to have at least a 20 mA output capability in order to complete the calibration series

[burningsuntech]

On second thought... You would need a 0 to 800 volt Transformer and use the variac to supply the variable voltage to it.

With a vernier dial on the Variac, you would have a calibrated settings range. If you need finer settings, say in millivolts, you would need a twenty-five turn vernier instead of a ten turn vernier.

Hope this helps.
RA

[burningsuntech]

ewpwrqlty
You could use a switch to select one of two ranges. The first range would be what is supplied by the Variac. The second range would be addition of another step-up transformer connected to the output of the variac.

With a Vernier knob attached to the variac and a volt meter, of course, you could tune the output of the step-up transformer to the appropriate ranges based on where the vernier is set.

That would give you your ranges and the desired voltages though it might be a bit cumbersome.

One other possibility would be to calculate the output of a transformer given the input voltage and the number of turns on the output. If you are adventurous enough, you could design and wind your own transformer for the desired output ranges beyond the output of the variac and use a selector switch to select the output tap for the given range you desire.

It takes some doing and a bit of knowledge of transformers but it can be done.

Lastly, you could also have a special transformer built for this purpose which would give you all the ranges based upon which tap you choose.

There are other methods but I do not build devices for people nor do I have the time for these projects as i am currently busy running a business.

Good luck. i hope this helps.
RA

[ewpwrqlty]

I need to build a variable AC power source from 0-700 Vrms for calibrating my BMI 8800 power disturbance analyzers. There are 8 voltage ranges that the power source needs to provide: 0 Vrms, 7.6-8.4 Vrms, 15.1-16.7Vrms, 30.2-33.4 Vrms, 75.5-83.5 Vrms, 150-170 Vrms, 200-225 Vrms, 300-335 Vrms, and 604-670 Vrms.

Do you have any suggestions? Any help would be greatly appreciated.

[CharlesBarret]

Hi, i think that your source cannot supply that much current (20milis) because that depends on your load resistance.. mmm how do you know you can hold that much current in your design? thx..

[burningsuntech]

CharlesBarret Technically true. The problem is with the type of transformer used in this supply. The specs of the OBT state that it will supply .02 Amps at 6000 volts. This transformer does have a load in the form of an air gap approximately 1 cm in length. With the resistivity of air equal to anywhere from 10^8 to 10^9 ohms per meter then resistivity of a one cm gap is 10^6 to 10^7 ohms. This assumes that the air has not ionized. (which is the point of an OBT anyway). After ionization of the air, the conductivity increases dramatically to the point of a near short circuit. To prevent that from becoming a dead short, there are current limiting windings built into the transformer to limit maximum draw to 20 ma. So, the maximum draw from this device is limited to 20 ma. But if there is a resistive load placed on this supply, it will be somewhat less based on Ohms law. Hope that explains the specification. Thanks for the question. RA

[silicacat6]

Would you please assemble and sell me a high voltage DC power source? Input either 24 V DC or 220VAC, your choice. (I would prefer to use 24V DC input). The max voltage required ~900V and max current 5A. Name your price, and have a guess at when you could deliver. Thanks [e-mail]

[skeric17]

hello i was wondering if u could please give me a few pointer on making a 0-12v variable power supply i dont know where to begin thanks for ur time and help=]

[burningsuntech]

I can point you in the direction of either the internet or Radio Shack engineering booklets which would have circuits that would work for you. Do a Google Search for 12volt power supply schematic. There is tons of them out there. Good luck with your project. RA

[simondodd]

Great job!! I am thinking of building this with myNST and using it for my Tesla Coil.  However all the plans I have seen for Tesla coils require both the hot and cold output from the NST. Would this be the HV output and the case/ground or would I have to wire it up slightly differently?

Thanks in advance

Simon

[ElectricUmbrella]

Hi, very nice idea, five stars!
I don't have an six KV Oil Burner Transformer, but I do have a five KV Neon Sign Transformer. Would that work just as well?

[burningsuntech]

ElectricUmbrella
Yes it will.  In fact even AC (mains) passed thru a standard transformer (ie 120VAC in and 120VAC out) will give you a high voltage based on the formula in the multiplier design.  Thanks for the 5 STARs.  enjoy the build.

*** Do you have technical questions on electronics, computers, anything except plumbing, and house electrical?  Burningsuntech may have the answers.  Just email your questions to: [e-mail].  We will let you know. ***

[PureAwesomeness]

 Hey, it's okay, I got the parts in time and it turned out fine!

[Dr.Bill]

Aaaaaahhh! I Like Electricity !

[BobLew]

what should i do with the other pins?
sometimes spark occured between them.
especialy some closest pins with ground pin.
one of pin closest is also draws purple spray, but never spark

[PureAwesomeness]

HELP!

Okay, I'm doing a science project in 8th grade involving electrohydrodynamic thrusters, and I need to know how much all of this costs.  I need this stuff in like 3 days or less.  Assuming I can get a crappy TV that still has a working screen from Good Will, what will be the cost of everything else?  Also, what are the RadioShack ID numbers for all of the stuff that you say I can get from RadioShack?  I could probably get the rest from Amazon, which ships in one or two days.  For everything else, if you can, could you please give me links to the products?  I'm sorry if I'm asking a lot of you, but I'm desperate, and I'm awful at finding the right electric parts via the internet.  Can you help me?

Thanks, PureAwesomeness

[burningsuntech]

PureAwesomeness

Sorry for the late reply.

If you waited till you only had three days to assemble this project, then you set yourself up for failure.

If you intend to do anything in science or the engineering field, you have to do your own research like everyone else.  I cannot give you any assistance about pricing of parts etc.  Thats your problem.  Do the work if you want the reward.  Otherwise you might consider simpler projects in the future.

RA

[thermoelectric]

When you say Multiplier for raising the 6000 volts to 50,000 volts at the same current. How is that possible? I always thought when the voltage went up the current went down.

[burningsuntech]

thermo the source of the current is the transformer and it is rated with an output of 20ma. If the tranformer output were passed thru another tranformer with a 6000 volt primary and a 50,000 volt secondary, then you would be correct. The stepping up of the voltage in this manner would cause the current to step down. However, the device we are using (ie the multiplier) is comprised of capacitors that charge in parallel during one half cycle of the AC input and discharge in series on the other half cycle. The multiplication of voltage using this device has virtually no effect on the amount of current delivered because the capacitors will charge to .707 or seventy percent of the peak input voltage with very little capacitive reactance. Therefore most of the current from the transformer is delivered to the output. RA

[thermoelectric]

Ah, Thanks, That helps. Would it be possible to get AC out of the multiplier? I know it has a DC output but sometimes that isn't too useful...

[burningsuntech]

thermo

This multiplier is classed as a halfwave device. That means that is uses only one-half cycle of the AC put in.

There is a fullwave version that would be a possibility. If you take the halfwave schematic and flip it on its ground line as a mirror image, you would get a fullwave device.

Go here for more info: http://members.tm.net/lapointe/Cockcroft_Walton.htm

• WARNING *

The fullwave multiplier is a dangerous monster. Notice in the schematic that all three output poles are at high potential with respect to ground. You will need to build this device with special design considerations in mind.

BTW - I have replaced the mineral oil in the multiplier with parafin. Works quite nicely too.

Good Luck
RA

[thermoelectric]

Oh, Wow! That sure looks dangerous! I might attempt it once I get my MOT bank running (4 MOTS with outputs in series), I can't wait to be drawing sparks at 500mA ~8800VAC *evil grin* May I ask where you obtained your mineral oil? (I thought parafin was flammable?!?!)

[burningsuntech]

Thermo Did you say MOT's??? Yikes man. be Wery careful silwy wabbit. MOTS do not have current limiting windings in them and therfore produce a HUGH amount of current. Just looking at one crosseyed can get you toasted. PLEASE! BE VERY CAREFUL! I would hate to lose a buddy. Raving Apache

[thermoelectric]

Yeah, i said MOT's. I have them current limited with a heater's heating element. I need to submerge them in oil before I even dare to pump a higher current through them, I already got the output of one of the MOT's to arc to the core :-/ And they actually do have current limiting shunts in them, just not very effective... I'll be careful, I would hate to lose me too.

[burningsuntech]

thermo Even mineral oil is flammable if you get it hot enough. I changed to parafin because it was easier to obtain and contain than mineral oil. It remains in its solid state as long as it doesnt get too hot, way below its ignition point. I got my mineral oil at Wal-Mart. or any drug store will do.

[thermoelectric]

You think the drug store would be suspicous of me buying a couple of litres of mineral oil? Lol. I need that much to fill the bucket my MOT's are in...

[burningsuntech]

thermo There are tons of more dangerous stuff in a drug store than mineral oil and I don't mean drugs either. An mineral oil is not dangerous. BTW - I dyed the parrafin red with a red crayon so I could detect any leaks in my pour into the container. No leaks but it looks techie, though. Cool.

[thermoelectric]

Cool! I'm gonna email my chemist to see if they have enough for my needs...

[Mudbud]

THATS A THIN WIRE!!! for 25kv? careful with that wire.

[burningsuntech]

Electro Nerd You mean the one shown on the pic with the arc from the stud? Actually, that wire is grounded and its voltage breakdown value is irrelevent because it is at ground potential. It happens to be 12 Ga. stranded AC wire. No if we were talking about powering from the stud, then yes, you should use a highvoltage rated wire of at least 25Kv. raving apache

[electrophysics_man]

Does anyone have an oscillograph of the output signal of this power supply? I would like to see what the output looks like before I build it in order to verify that it will work for my purposes before I purchase the parts and build it.

[elphreaker]

Nice instructable mate , you encouraged me to set it up , I have all the AC part done at the moment and tomorrow ill get the multiplier and the box ready ;)

[ushirmaharaj]

can i use this to power a marx generator

[burningsuntech]

HI Yes you can. The output is pulsating DC and should work for all HV applications drawing less than 20ma.

[ozetzioni]

Hey, I am building a pedal generator bike with a battery. at the end of the day i want to transfer the electricity i made of riding into a bigger battery and then use it for lighting equipment... anyone knows of a method to transfer the electricity from one battery to a bigger one without losing voltage or too much energy???

[anonomas29]

wire this up to a doorknob that u dont want people going in

[burningsuntech]

anonomas29 What about DEATH don't you understand? This is no toy but a serious instrument. Do you really want to go away for life for murder? You better think again! Raving Apache

[Derin]

no no no!use plasmana's smallest shocker for that

[ubr.bzkr]

or you can use that worlds smallest shocker to zap people for fun like I do. that was one of my favorate instructables.

[Derin]

That was what I was talking about.

[ubr.bzkr]

yeah. did you build one?if not you should, its real fun to use on/prank people with. i shocked abunch of random people at this huge scout camporee called peterloon.

[TheMadScientist]

earlier somebody said this has the power to drive tesla coils. you need DC to drive a tesla coil. therefore, you cannot.

[burningsuntech]

Mad Scientist Actually, You can drive a tesla coil with this device cause its output is pulsating DC and yes, it has the power to drive one. As far as the Diodes are concerned, a check on Ebay revealed some serious diodes that would set you back a few hundred dollars if money is no object. A ten amp diode at 20Kv will set you back nearly $150 and you need six in this configuration. My only question would be where you going to get a case and enough oil to drop THAT in? Raving Apache

[TheMadScientist]

love the voltage multiplier btw. but you need some hardass diodes once you get further up the ladder. tell me where you find yours please. not microwave gunn's either.

[bombmaker2]

i cant find any dpst relays

[burningsuntech]

I salvaged mine from an old dehumidifier but any relay will work if the contacts support 5 amps of current at 120 volts AC. Also look for them as 'contactors'. Raving Apache

[bombmaker2]

thanks

[Derin]

will this work for lower voltages

[burningsuntech]

Derinsleep This will work for any AC voltage up to the maximum of the diodes, in this case 12000 volts.

[Derin]

thank you

[alexhalford]

Presumably this would be perfect for a jacob's ladder or a telsa coil supply??? Also could you use a flyback for the HV transformer?

[burningsuntech]

alexhalford This definitely has the power to drive a jacobs ladder or a tesla coil. Just the OBT alone works as a nice jacobs ladder. In this design, you cannot use a flyback without some form of step down from AC mains. Also, the flyback is designed to operate at 15.750 KHz whereas this device runs at 60 Hz. You would need a circuit to produce the 15 KHz input. The multiplier would work with a flyback, though. Many TV sets have these multipliers built into the flyback as they are. raving apache If you were using only the multiplier section of this device then

[alexhalford]

OK thanks very much. BTW, do ignition coils powered by square wave pulsed DC generate high voltage AC or DC??? Thanks Again Alex

[burningsuntech]

Alex AC implies that in some way the output signal is positive then negative with respect to ground. DC implies that the output is either positive or negative with respect to ground but does not alternate between the two. With a square wave input from ground to positive and back, the output would be a pulsating DC high voltage. Remember. Transformers of all types are AC or Pulsating DC devices. They cannot operate on pure DC. raving apache

[alexhalford]

Thats what i thought... but in that case how is this setup appropriate: Above that diagram is written this text: This next circuit is designed for a higher powered output. Two ignition Coils are connected in parallel but with opposite polarity. This means that the output voltages of each coil are out of phase or opposite to each other (when one is positive, the other is negative). Using this configuration the output is taken from the two coils output terminals, whereas the circuit above uses the output terminal and ground. If the ignition coil is not AC and therefore never goes negative, how can the above be appropriate??? Thanks for all your help btw.

[burningsuntech]

Note: AC is defined as the alternating input of a current between two values. The fact that the values may be +10KV and ground does not negate the device as an alternating current device. Most people think of AC as a current that varies above and below ground but AC can be any current that varies between two positive values or negative values or between a positive and a negative value. It all depends on what your point of reference is. raving apache

[alexhalford]

Thanks very much it makes sense now. Alex

[burningsuntech]

Alex All thats really happening here is the switching of the input to two coils, both of which are ISOLATED from ground. Therefore, their output floats above or below ground. Believe me. If you touch one of the coil HV leads and ground, you're gonna get it! The coils produce 10KV Pulsating DC out of phase from each other. Therefore, the voltage across the two HV leads is 20 KV. One lead will be +10KV and the other will be - 10KV with respect to ground or 20 KV with respect to each other. raving apache

[Ferrite]

Does the power supply supply a continuous voltage or just a single pulse? If it is continuous it would be good for a laser power supply.

[burningsuntech]

Ferrite

The output is pulsating DC and the reason I built it is to power a UV laser.

Don't worry about filtering but be sure to use a current limiting resistor in series with the laser tube or you will destroy the tube. To calculate the proper value, use Ohms Law R = E / I

Good Luck and stay in touch. I would be interested to hear how you made out

raving apache

[bsibille]

If the diodes limit the current, what is the need for the resistor? Thanks!

[burningsuntech]

The diodes are 12 Kv PIV 550ma doides. They do not limit the current but they themselves cannot be used above 550ma. Since the supply is an open ended supply, that is it has no built in load, a current limiting resistor is required on all devices connected to it that do not need 20ma (the total source surrent of this supply). In other words. The supply will try to supply current all the way up to its short circuit point if you do not control the load with a limiting resistor. raving apavhe

[Ferrite]

Thanks! I haven't built a laser yet, but plan to soon.

[agis68]

Excellent project, and very carefully done! Of course you can replace the VT1 with one of 220V for european countries.

[burningsuntech]

Thanks Agis Any neon sign or oil burner transformer of either mains voltage will do as long as you follow proper wiring procedure and pay attention to the specs of all the components. Raving Apache

[agis68]

Thanks again...i will try to make one and i will be in touch with you for any detail... @gis

[bwana]

could the output of two neon transformers be connected in series? (to boost arc size for a jacobs ladder)

[burningsuntech]

bwana you cannot place two neon transformers in series as the output of the first would most certainly cause damage to the second. Instead, why not just add more stages to the multiplier. It currently has 6. Please see the link to the multiplier for more info on it. raving apache

[alexhalford]

Also what current will this put out???

[alexhalford]

hi could you use a neon sign transformer instead of an oil burner transformer???

[burningsuntech]

alex You can substitute a neon transformer for the OBT. The OBT was what I had on hand at the time. Both types of transformers have current limiting windings in them. As designed, this device will source up to 20ma at 50Kv raving apache

[sounder]

Could an automobile ignition coil be used in place of the OBT? I know the ignition coil is an autotrans with a common point between pri. and sec. windings but the turns ratio is so much higher that the voltage multiplier wouldn't be necessary.

[burningsuntech]

Perhaps. The two devices are similar but the Auto coil is a pulsed DC high voltage, low current device whereas the OBT is an AC high voltage, high current device. Ive attempted to drive an auto coil with 12 VAC only to find it getting hot and not able to produce the current I was looking for or the spark length I wanted. If you decide to build one with an Auto coil, let me know how you make out.

[static]

Comparing an auto ignition coil operation to an AC transformer operation is comparing apples to oranges. While the ignition coil is constructed like an autotransformer, it's not a transformer per Se. DC flows through the ignition coil primary for enough time to create strong magnetic field. Current is produced in the secondary when the current through the primary is turn off and the mgnetic field collapses. I suppose if an ignition coil was feed AC of a frequency near what coil sees when doing the job it was designed for it MAY operate as conventional AC transformer. Problem is that would be at least 800 Hz.

[membrane]

An NST or neon sign transformer could be used instead of the furnace transformer in a circuit like this and actually would work better then the OBT as NST are inductively current limited so they're less likely to self destruct if shorted. An automotive ignition coil would yield less milliamperes but higher voltage as some do operate at 50KV but you would need some sorta DC PWM circuit vs a variac as hooking 120v AC to a 12v coil would be a bad idea.

[burningsuntech]

Roger that, membrane. NSTs do work well and would be a good choice. The OBT is what was onhand.

[Fro]

Seems like a really great project and I might just build something similar, but I didn't really understand if the output is AC or DC. Also, in place of a variac could you use a basic light dimmer since they're much cheaper, or does the fact that they chop up the sine waves cause problems?

[burningsuntech]

Hey Fro The output is pulsating DC or unfiltered DC. As for the dimmer, you can use one rated for inductive loads like motors and, in this case, transformers. Standard light dimmers are for resistive loads like incandescent lamps and would not work. The only exception would be to use a dimmer directly into the multiplier and leave out the OBT. Make the multiplier large enough and you could drive it directly from the AC line. BTW the output of the dimmer doesn't matter if noise on the output doesnt bother any circuits attached. Good luck. BST

[Fro]

thanks

[littlechef37]

awesome man, nice instructable id love to make one but im not that resourceful and it would be a hazard!!!!!! in my hands any idea on how to make a smaller one for running motors and stuff ?

[burningsuntech]

Hey littlechef thanks for the compliment. Depends on what you are running. Any AC motor could be run from a device similar to this if you had a large enough Variac. This one is too small for most AC motors and is for lights only or in this case loads that draw no more than 2.5 amps. Your best bet for AC motor control is a triac with a variable pot to control the speed For DC motors you would need a special controller or a large Rheostat tha could handle the current. Google some of the terms in my reply and find a circuit tha will do the job. BST

[littlechef37]

thanks

[bumsugger]

Nice one "burningsuntech" a very neat and accurate "build," great device!

[burningsuntech]

Thanks bumsugger. It took awhile to put together and document. Im looking to sharing more on this subject in the future.

[xrobevansx]

That case isn't *exactly* a TI99 4/A "case" so to speak. Isn;t it a Ti 99 4/A hard drive case?

[burningsuntech]

Yes it is. But who would remember that far back in computer history anyway. You and me maybe. Thanks for the clarification.

[membrane]

Looks like the TI 99/4a PEB or peripheral expansion box it added 8 expansion slots to the 99/4a I actually own a functional example.

[xrobevansx]

40 megs if I remember correctly. A POWERHOUSE!!!!

[!Andrew_Modder!]

omfg! that is crazy man! That is really awesome, but honestly i cant think of anything that would be able to run up to 50,000 volts :-P! Hey, also couldnt you make plasma, or a tesla coil with that, cause its really f'ing high voltage :-)? ...1st

[membrane]

An adjustable HV psu in this range also is useful for powering those antigravity lifters or a Marx HV pulse generator.

[burningsuntech]

Well, not just high voltage stuff. im planning a laser project and need to adjust the voltage for tuning. Conceivably, you could build a large enough stack in the multiplier to get to 500,000 volts or more but it is very costly. Thx

[!Andrew_Modder!]

lol you could make a 1 million volt power supply >:-D, that would be SOOOOOOOOOOOOO deadly, and I would be so unconfterable to store that or use it. hehe >:-D

[FrenchCrawler]

Yes he can. I was gonna do one of these (got side-tracked, but still have the parts) based on rmcybernetics' design (with permission first). It's different then this though, but probably more expensive (due to the diodes).

Also might want to add a EMI/Spike filter to prevent the mains from receiving damage.

[burningsuntech]

French Thanks for the EMI filter addition. That along with several changes are planned for version 4 of this project, including complete encapsulation of the multiplier to eliminate an oil leak problem.