building step up circuit 12,000 volts - help!!!

Discussion in 'General Electronics Chat' started by rudyauction8, Jun 7, 2012.

Jan 27, 2012
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I was wondering... I saw some 120-12.6 volt transformers at radiosnack, if I used 3 reversed in series, and used 12 volts AC to power them, would they give me ~12,000 volts or short out somewhere along the way. I am trying to make a circuit that generates small sparks. I was thinking a large one (~3 amps) first, then small ones (~1 amp) for the higher voltages. I know they aren't designed for high voltages, but would they work? They only need to last for a week or 2.

2. #12 Expert

Nov 30, 2010
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Not work. The second transformer would be fed with 120 volts on its 12V winding. Fast smoke. Better to try the transformer out of an oil furnace ignitor.

Jan 27, 2012
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Even though the 120 volts will only have a current of about 50ma? I was going to use a 500ma 12v AC power supply for this. If it will smoke out, then I may be out of options. I could also use single pulses of 12volt dc to reduce load. Or does it short out because the 120 volts goes through the insulation? I'm honestly more worried about the third, when 1,200 volts is fed into the 12 volt coil at something like 1-5ma.

Is it possible for me to make my own transformer(s)?

Apr 5, 2008
15,809
2,390
Hallo,

There probably will also be problems with the isolation of the transformers.
It can be that there are sparks made INSIDE the transformers that may burn the transformers.

Bertus

5. #12 Expert

Nov 30, 2010
16,705
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You are correct to be more worried about the third stage. Whatever might go wrong with the second stage will surely go wrong with the third stage.

There are many ways to make a spark. Car ignition coil is one way.
It is possible to make a transformer, just much easier to find one that is already good enough.

Jan 27, 2012
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my goal is a simple to build circuit that can generate sparks at least once per second that are about 1cm long, give or take. A car coil would work, but how does the circuit around it work, and how high of a voltage can I get from it? I would like to push what ever I use to the limit, if a car coil can give me 1 inch long sparks, that's what I will do. This circuit is just for fun, so the only restriction is the price. I can pick up a car coil at a junkyard today or tomorrow, but first, I need to know the details of how it works.

7. #12 Expert

Nov 30, 2010
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I'd say a 555 timer oscillating at 1Hz with a low duty cycle, to a MOSFET that allows current through the low voltage side of the coil. When the MOSFET shuts off, a frewheeling diode allows the primary coil to collapse and the secondary coil kicks out a spark.

is that enough?

Jan 27, 2012
252
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I understand up to the diode. How and where does it go? I'm new with transformers. And how much voltage can I use? Could I use ~24 volts for a bigger spark? I have a few 18-30 volt power supplies from laptops to work with. Again, it only has to last a few weeks of 2-3 minute uses.

Oct 8, 2011
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10. #12 Expert

Nov 30, 2010
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I can't top that!
However, I can give you a dirty look for trying to up the voltage until you finally get it to fail.

Jan 27, 2012
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Wow this is getting way more complicated than I can handle... You don't just pulse 12 volts into the coil and get a spark on the other end? I've never heard of some of those parts! I have built 555 circuits that power transistors to flash lights, simple enough, is there a way to easily attach one of these to the coil? and what's the difference between a regular diode and a zener diode? I have seen 12 volt zener diodes at radioshack, would they work if I used more? And what are they even there for? Could I just use a relay to pulse the coil? I want to try to stick mostly to parts I have - 555 ic, pnp and npn transistors, 1 relay, assorted capacitors - 35 volt, .47-470uF, assorted resistors - 1/8-1/2 watt, 1 each pnp and npn 75 watt transistors with heatsinks, assorted leds, 2 each 1 amp and 3 amp regular diodes. I can get a few components at radioshack, but if I have to get a whole new set, I will move on to another circuit.

12. #12 Expert

Nov 30, 2010
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You could use the 555 to power a relay. It will work because 1 per second is slow enough to use a relay.

Jan 27, 2012
252
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OK then just pulse 12 volts through the relay into the coil? Does using the relay eliminate the zener diodes? If so, I will get started in an hour or so.

14. #12 Expert

Nov 30, 2010
16,705
7,358
yes.......

Jan 27, 2012
252
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Thanks I will post any problems.

16. BMorse AAC Fanatic!

Sep 26, 2009
2,675
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one thing I could see happening is the OP gets zapped and killed with 12,00 volts at 1 amp.. and powered by the mains nonetheless .... Newbies should really not be playing with things that could potentially injure or kill themselves or others.. and those that help, might as well have a hand in it too...

These kind of circuits are usually forbidden on this forum, wonder where the mods are??

17. #12 Expert

Nov 30, 2010
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Yeah. Good thing he started out talking about using transformers and ended up with a 12 volt battery or he could get in real trouble!

Last edited: Jun 7, 2012
18. cork_ie Member

Oct 8, 2011
348
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Uh where is the 12,000 Volts at 1A? - That's 12 KW . Any ignition coils that I know of are about 100W max - older non electronic ignition coils used to draw 3-4Amps on the low tension (12Volt) side that's 40-50W

By the way OP if you decide to use a relay put a 0.1μF capacitor across the relay contacts , it will give you a far better spark due the oscillations in the circuit and will also reduce arcing and burn up of the relay contacts .

19. #12 Expert

Nov 30, 2010
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Most of us figured out the OP couldn't get a 12,000 watt arc out of a transformer he can pick up with one hand, so we ignored that part.