I already have the HV transformers. I ripped out their primaries and replaced it with 1-2 turns of 14 AWG stranded copper wire with insulation. This works much better. Pulsing about 10-15 amps through them (by essentially shorting a cheap Chinese power supply), and releasing then contacts, I get some noticeable HV arcs. It can jump across at most 1/2 cm air gap, and the humidity here where I live is ~40-50%. I created the gap with some bolts and nuts to adjust it easily. I tried it with a pushbutton, but it welded shut and created a burning mess. So it works but I still need a real circuit.

I also got the 60V boost converter from drok. There is a large 470u 63V cap on the output. It has no short circuit protection. So I briefly shorted it through the primary. I made sure it was no longer being powered, but the cap was at close to 60V. It has a bleeder that discharges it in about 20 seconds. But then I got nothing on the output! NOTHING! I did not even see tiny arcs when moved closer together. I tried many times, just to get the same result. So maybe this isn't the best approach. And when the output was accidentally shorted with a very thin wire, it brightly arced (more like made a huge spark, not HV) and made a deafening sound. So maybe I did something wrong and it was not really at 60V (I know it was at least set to 60V). Or does it being an inductor mean it opposes that instantaneous current flow? Because regardless of what went wrong, it was very disappointing.

So this means back to the drawing board. I am leaning towards some other sort of oscillator that is more continuous. Being honest, I would rather have weaker but larger arcs (voltage over current) for safety reasons and for other applications where voltage is more important than current. I know this compromises the functionality as an arc lighter, but it may be necessary. It will probably still be good as a bug zapper though. Maybe even better. I really do not want something that can supply more than 2-3 mA because given that I have already been shocked a few times, and it may happen again, I do not want the risk of fatal electrocution.

The problem seems to be this. If you want more voltage on the secondary, you need more on the primary. With such a low resistance and inductance, it is hard to get higher voltages without huge current demands. You could try and get inductive spiking, but even then it is still pretty small because of the low inductance. At least the high currents there help. But then this can be hard to manage and it can be difficult to keep the components alive. Most mosfets will not be happy with a few 100 volts, even for a tiny fraction of a second. Zeners may not be fast enough.

I am not really sure how to design a circuit that gets very high voltage but low currents here, and has a reasonable power consumption. I want it to not be incredibly complicated, but I want it to still work well. I could easily rewind the transformers to get center tapped or more turns or whatever. I know the basics of inductors but I really would need to learn more to design something that works well. I know a little about LC resonance but really need to learn more to design a good circuit. So if people could suggest some good resources that would be great. And ideas for designs would be great too.

I am thinking of using some huge inductor to get huge inductive spikes that get amplified even more through the transformer. Maybe I could step up the voltage with the boost converter and have it momentarily draw large currents to power the inductor. I am thinking if I can use a much greater inductor and use 60V momentarily, the arcs will be a lot more real. But I am not sure how to make a circuit to do this and not damage itself. I could probably make one with digital logic, but usually there is a much simpler and more effective circuit that does not use all that logic stuff.

Later I got bored and made a very simple EM relay circuit. It now gets nice, continuous arcs (though I am not satisfied with the length). It initially powers a relay that powers the primary. Then the voltage drops. I could use real CC, but I decided to use a 6V power supply that can supply 12-13A when shorted through the primary. It delivers the current but drops the voltage. Then when that happens the coil switches of. The power is cut, you get inductive spiking, and you also then have it return to the normal 6V. But it turns the relay back on, and this cycle repeats. It being EM and not SS, it makes an annoying buzzing sound. And the contacts got welded together many times. But "percussion maintenance" fixed that.

 

Here is some of the stuff I have done with the HV. The 23 second one is my lightning charger for iPhones. I don't know if apple would approve though.
https://photos.google.com/share/AF1...?key=cGp0VlFjUWViUnFDdW00em9Jc2NUN3dRM1k2bW9n

 

Suggestions?

 

Buy this thing for $1.76 and have:

High Voltage Transformer DC 3v-6v to 400kv Boost Step-up Power Module Generator

 

400kV sounds like BS. Those things, from what I have heard, usually only get up to a small fraction of the stated voltage. And regardless, I want to at least make it myself and gain experience designing these types of circuits. But given how cheap it is, I may as well give it a try.

So what if I used a circuit like this https://photos.google.com/share/AF1...wkey=Z1FTS2JHZTBNZ0IxOEVoYW5RbmxKRi1WYmRqbW13
The basic principle is you switch an inductor with a very high inductance and high ESR. You use a diode to prevent reverse current flow. Then when it is turned off you have huge inductive spikes that go through a diode then something like a solid state arc gap with zeners, and IGBT, and resistor. That pulses high voltage through the primary which steps it up even more across the secondary. But would this work? Or would a dual resonant circuit be better here?

 

See how simple is schematic and how efficient it is.

What is inside?
(reverse engineering this generator)

 

Efficient or effective for cost and other limitations? Because I usually don't trust the simplest way to be the most efficient or the most effective.

 

Efficient or effective for cost and other limitations? Because I usually don't trust the simplest way to be the most efficient or the most effective.

You are right. It is feeling only.
Receive generator from ebay, measure simultaneously input (voltage, current) and output (voltage, current), then calculate efficiency.
It is only way to compare these circuits.

 

I have no idea how to practically measure that at such high voltages. I do not even have a scope yet.

 

I have no idea how to practically measure that at such high voltages. I do not even have a scope yet.

It is very easy to ask Google: "Energy measurement of spark discharge"
For comparison energy of sparks from different devices you can use normalized spark gap in DIY calorimeter.

 

But how do you measure current and not just voltage?

 

You have not oscilloscope, therefore you will use calorimeter for measurement energy of spark, not current, not voltage.
Input current and voltage you will measure in time (1s for example) of spark lasting.
Please, read articles in Google pages.

 

See how they did measurement of spark energy almost 100 years ago.
They used thermocouple and galvanometer.

 

I initially thought that you needed extremely dangerous and large currents to get powerful arcs. Because I do not want this kind of risk, I decided to go with something that would maybe get some very low current high voltage arcs to test dialectics and stuff. But even 3 mA at 15kV would be 45 watts. So the currents required can't be too high, right? And that means that therefore you could get powerful arcs without the danger of fatal electrocution.

But how would you design a circuit to actually get a voltage that is within that approximate range and limit the current to less than 5mA? I know you could add a series mega-ohm resistor, but that means a lot less power across the arc gap and the resistor could fail. Regardless, there would still be points in the circuit with lethal voltages and currents. I am concerned that a circuit may try to deliver 10s of mAs on the output, and will just drop the voltage and still deliver that lethal current. So what do I do?

Also, is the HV still dangerous even when limited to less than 5mA? Would there be the danger of momentary HV high amps and/or breakdown of tissue from dialectric being reached or something like that? I know that it is likely that you may be burned due to the high power dissapation, but I am more concerned about other more permanent things.

 

I go camping every year in Vermont. I use a traditional lighter for the camp fire. But inevitably it will run out of lighter fluid and I will have to buy another one, or more lighter fluid. The cost will add up. However, I have heard of these arc lighters that use high voltage arcs to ignite things. It would be a good experience to make one and the electric version would have many advantages. It could last me many years if I use a rechargeable battery for it and design a good circuit. I also may want a HV generator for a demonstration jacob's ladder or something like that.

But I am concerned about safety. I either want it to be limited to less than 5 mAs or for it to be in very short pulses so that it is not too much worse than static discharge. I am okay with the risk of burns, but not of fatal electrocution. I also do not want excessive UV or other damaging particles emitted. I understand many of the circuits used, but do not know too much about what is required for arcs. I know you need a certain voltage for a certain distance, but I do not know too much about the current requirements.

So is it possible to design a circuit that will get continuous arcs (not just one when you initially press a button or release it) and not have the dangers I mentioned? I also want the biggest arcs possible for something that is portable and safe enough. More voltage (hypothetically) means more current limits and bigger arcs, which would both be good. I want it to arc across at least 1/2 an inch, so that means 10-15kV with dry air.

This is my idea for one that has very short pulses. I am not sure if it is practical though. As a bonus, it should have a long battery life. A capacitor gets charged by a 9V rechargeable battery (I have a few lying around). It gets charged very slowly through a high value resistor. It should take about 200mS so that it is only short bursts. Then it quickly discharges through a HV transformer after it gets to a certain voltage. There is a schmitt trigger that is high if it is above 7-8V and low if it gets below .5V. This way it starts discharging at 7-8V and stops at .5V. Then it gets slowly charged again. It should cause inductive spiking in the primary and even bigger voltages in the secondary. I am not sure how to get that spiking without the risk of damaging the components though. Any ideas? Or maybe another circuit that can get HV, pulsed or continuous? And would I be able to simply add a megaohm resistor in series to limit the current but still get the same arcs? Also, how long can you handle a few amps? Is it 1-2uS or 1-2mS, or somewhere in between? This would be important in designing it to be safe enough. And what about a few uS but multiple times per second?

I used this online calculator to find out the time it would take to charge and discharge a cap through different loads. It should help me find the right R and C.
http://mustcalculate.com/electronic...arge.php?vfrom=0&vto=7.5&vs=9&c=20u&time=200m
http://mustcalculate.com/electronic...ischarge.php?vfrom=7.5&vto=.6&vs=0&c=20u&r=.4

I won't think a small coil would be enough. If you need a high power generator then I would recommend that you go with Ardokit DC 3.6V-6V. Its nice smal high power generator for any arc lighter

 

Every time I am in Harbor Freight (way too much lately) I eye the $3 electronic fly swatter. I think it is DC, not ac, and may not output enough voltage for you.

But... For $3 it would still be fun to play with.

 

I won't think a small coil would be enough. If you need a high power generator then I would recommend that you go with Ardokit DC 3.6V-6V. Its nice smal high power generator for any arc lighter

Did you miss the whole discussion about stun guns not being able to ignite things? And I know it is not .4MV because it is not made for a gap of 1/2 a foot! I do not want to buy BS products. I would much rather make something. And I want to get that electronics experience. So how do I make it limited to less than 3mA on the output? And are there other dangers of current limited high voltage? I want the power circuitry on the low voltage side to limit it, not a resistor. Look at post #74. But thanks for the suggestion.

 

So how do I make it limited to less than 3mA on the output? And are there other dangers of current limited high voltage?

Just like everything having to do with electricity, it is the current that does the actual work. That is why the stun guns won't start a fire, even though they have the high voltage. They have such little current. By design, they are to subdue someone, not set them on fire. If you want fire you need the current.

 

Just like everything having to do with electricity, it is the current that does the actual work. That is why the stun guns won't start a fire, even though they have the high voltage. They have such little current. By design, they are to subdue someone, not set them on fire. If you want fire you need the current.

More than just a few milliamps to light kinder on fire? Because at a few Kv that's already 10s of watts.

 

Firing HV spark:
http://www.instructables.com/id/Start-Fires-With-Electricity-DIY-Arc-Lighter/