With what you're trying to do with your circuit, why not make it easy on your self and get a used "disposable flash camera" and take the circuit form that? Most drugstores will even give you already used ones for free. https://www.bhphotovideo.com/c/prod...MI8b3Dr5vn2gIVzrrACh3TMQp5EAQYBSABEgKeRvD_BwE

I know you want to "build it yourself", but before spending much time and money to make something that won't do what you expect(as many here have told you), get a few of those and experiment.

 

What problems would I realistically encounter? What would cause it to behave in such an undesirable manner? Other than difficulties managing the inductive spiking and possibly with the discharge mosfet, I do not really see any problems. And could you suggest some specific components for this? Also I do not want to also have high voltage capacitors in it, especially if it is supposed to operate in humid environments and be in your hand.

 

I ordered 2 of these step up transformers. They should get here in 16 days.
.

Build a PWM similar to this to drive the them.
http://www.discovercircuits.com/DJ-Circuits/simplepwm2.htm
Also https://www.electronics-tutorials.ws/waveforms/555_oscillator.html
Max.

 

But my idea naturally creates a low duty cycle PWM, and gets huge bursts of power. That allows much more powerful but shorter duration arcs. It is maybe unconventional but I do not see and big problems. So unless you think there is absolutely no hope could you please help me find the components and fine-tune the design? The goal here is to make something that works well and is safe enough, within a decent time-span. But I do not just want whatever is quickest.

 

But my idea naturally creates a low duty cycle PWM, and gets huge bursts of power. That allows much more powerful but shorter duration arcs. It is maybe unconventional but I do not see and big problems. So unless you think there is absolutely no hope could you please help me find the components and fine-tune the design? The goal here is to make something that works well and is safe enough, within a decent time-span. But I do not just want whatever is quickest.

Allowable accessible voltages

Many product safety standards set voltage limits for accessible parts, typical voltage limits set by a standard might be 60Vdc / 42Vac.

However higher voltages are permitted with the proviso that the available current that can be drawn meet set criteria; the product safety standard 60950-1 defines these as ‘Limited current circuits’.

The current limits set out in that standard are based on the current measured as a result of the output loaded into a 2k ohm resistor; with the dc current limit being 2mA – and the ac limit being 0.7mA. For frequencies above 1kHz, the limit of 0.7mA is multiplied by the value of the frequency in kilohertz, but shall not exceed 70mA.

A further requirement of a limited current circuit is that the applicable limits are met under single fault conditions – so with any single fault within the generating circuit, the allowable current into a 2k ohm load is not exceeded.

The value of a 2k ohm resistor is meant to represent a human contact load – and the increased current limits at higher frequencies reflects the fact that the human body can withstand high frequency currents.

 

What problems would I realistically encounter? What would cause it to behave in such an undesirable manner?

Is that directed at me? I'd like to see one device like you are wanting to build that is used to ignite a solid fuel, like wood or paper even to make things easier on you. Gaseous fuels, yes, but don't know of anything using a spark of any frequency to ignite a solid fuel. I have a very high voltage stun gun, that will spark right through a couple of sheets of common printer paper, but just makes a small diameter hole through the paper, no flames or any type of ignition at all, no matter how long you trigger the button. Just not enough heat involved in a spark like that.

 

shortbus.....check out second video in link on post #5. Skip thru it til 1:35.

 

Even with many kilowatts it would still not burn a piece of paper or kindling? And it is not also to igniter things, but also to to display arcs large HV arcs. So could you please offer suggestions for components and improving the design? They would be greatly appreciated.

 

Allowable accessible voltages

Many product safety standards set voltage limits for accessible parts, typical voltage limits set by a standard might be 60Vdc / 42Vac.

However higher voltages are permitted with the proviso that the available current that can be drawn meet set criteria; the product safety standard 60950-1 defines these as ‘Limited current circuits’.

The current limits set out in that standard are based on the current measured as a result of the output loaded into a 2k ohm resistor; with the dc current limit being 2mA – and the ac limit being 0.7mA. For frequencies above 1kHz, the limit of 0.7mA is multiplied by the value of the frequency in kilohertz, but shall not exceed 70mA.

A further requirement of a limited current circuit is that the applicable limits are met under single fault conditions – so with any single fault within the generating circuit, the allowable current into a 2k ohm load is not exceeded.

The value of a 2k ohm resistor is meant to represent a human contact load – and the increased current limits at higher frequencies reflects the fact that the human body can withstand high frequency currents.

My observation is that most product safety standards are intended to protect the unknowing people who randomly poke into things with zero forthought. That is to say that those standards are intended to protect fools without any sense. A simple understanding that high voltages and high temperatures are present, and the willingness to avoid poking into understood hazards will be enough to avoid injury.
Anoher way to put it is that those standards are created to thwart natural selection.

 

shortbus.....check out second video in link on post #5. Skip thru it til 1:35.

I'm proven wrong. But my 1/2 million volt stun gun won't even do it, guess printer paper is too thick.

 

I have indeed ignited both paper and wood, and accidentally ignited plastic . All that is from a steady arc from a 15milliamp neon sign transformer. All it takes is for the integrated watt-seconds divided by the product of mass x specific heat to exceed the ignition temperature of the material. But don't choke on that equation, even though it is a big thing. What becomes clear is that it is the time that the heat is available that leads to the ignition of the material. So really, any spark type lighter is going to be sort of dangerous. And also bigger and heavier than a large collection of those Bic lighters., or even a few dozen match packs.

 

I have decided that I do not want to have more than 500mA CC for the cap because I am going to try and prioritize size and capacity of the battery and I also do not want to deal with big power losses. I also want it to be PNP to achieve have it on the high side. So I found this BJT that looks promising on mouser. It looks like there is a fairly constant gain of 40, and it can handle up to 50 watts, so I do not anticipate too many problems.
https://www.mouser.com/ProductDetail/863-MJE15031G
But should I enhance the heat dissipation with a heat sink if I plan to dissipate 15-30 watts across it continuously? I want to minimize size and extra components, but I do not want unreliable performance from it.

For the capacitor, I am probably going to use some of these in parallel. They have a very low ESR and a decent capacitance. This allows maximum power dissipation across the coil.
https://www.mouser.com/ProductDetail/80-A759PY337M1JAAE42
Often 35-60V really means 34-61V for a DC-DC converter, but even then I think 63V should probably be enough of a safety margin. But do others think it is cutting it to close?

For the protective zener diodes, I still have no idea what to look for. So if people could suggest zener diodes from mouser that are very well suited to protecting against such surges, that would be great.

I also am not sure what to look for in the discharge mosfet. I want to minimize size, have a gate-source resistance of less than 30 milliohms, but most importantly it must not need more than a few watts to turn on and off quickly, while controling 100s of amps. So can someone suggest a mosfet that is well suited to pulsing like this? Or is the only option to have the capacitor itself turn on the fet? I really want to avoid this.

For the schmitt trigger, I am completely unsure what to look for. I need something that allows you to set the upper and lower thresholds with a variable voltage (potentiometers), is fast responding, and consumes minimal power. It should run off around 5V or be able to tolerate around 60V. I would also be ok with using two comparators an a r/s latch if that is more practical here or easier to find parts for.

It has actually been pretty hard to find a pushbutton that can handle 500mA at 60V. They seem to generally have low DCV ratings. Can I ignore them if they are rated for at least 500mA? It seems very that they will start arcing at 60V, so can I go with a lower voltage same current one?

Here is what I am looking for in a battery pack. It must not be larger than 4.5" by 2.5" by 1.5" (LWH). It should have integrated charging/protection circuits. It should have a minimum voltage of 11V before it cuts off and be able to supply at least 4 amps (a little less is ok). The nominal voltage should be around at least 14.4V. It should have a capacity of 4Ah or more, allowing at least 1 hour of operation. Capacity is really the priority, and I could adjust the design if it cannot handle that much current draw.

Finally, there is the subject of safety. Other than if you touched both HV leads at the same time continuously, or if it went directly across your heart, is there any way it could be fatal? And should I limit the capacitor size to make it safer? Does it discharging for 50uS or 1mS across the primary make a difference, or due to inductive properties, does it will only get the HV when the pulse starts and ends? If the only way to prevent it from being excessively dangerous is to add a current limiting resistor on the output, then I will do that. But I am hesitant to do that because I still want to have powerful arcs that would allow it to burn things. So how do I balance safety and functionality here?

Also, I hope this is not against AAC policies, but I plan to use it as a deadly weapon (taser).....
for mosquitoes. I will bring them to justice! I will no longer stand by and watch innocent people get annoying mosquito bites!

 

If you are hoping to produce a mosquito zapper you will still need an arrangement to deliver the zap, and that will be a challenge. My commercially made bug zapper killed a lot of moths and quite a few flies but it did not seem to attract or destroy the little biting beasts. Possibly a thing like a cross between a fly swatter and a tennis racket, with closely spaced conductors of opposite polarity would allow an active attack on a pest, but it would be quite fragile, and you would have to have a momentary action switch to shut it down when you released it.

 

As a bonus I have heard that ozone repels mosquitoes. But I do not really plan to use it too much for that. Anyways, suggestions for components?

 

As a bonus I have heard that ozone repels mosquitoes. But I do not really plan to use it too much for that. Anyways, suggestions for components?

There are two websites that have lots of circuits for assorted high voltage stuff in their "power" sections. One is the "freeinformationsociety" and the other is "schematicsforfree" site. I find both of them interesting, but they have no discussion groups and they are quite different from this one.
The circuits for inverters are what I am suggesting as a source for component types, but probably you would need to wind the transformer yourself.

 

I am ordering some from HV transformers from amazon. I posted the link in a previous post. Would I have to rewind those? And is my idea with the high power cap discharge not practcle? Or would I just need to modify the design a little?

 

I am ordering some from HV transformers from amazon. I posted the link in a previous post. Would I have to rewind those? And is my idea with the high power cap discharge not practcle? Or would I just need to modify the design a little?

Google Automotive coil circuit, using 555 etc.
Max.

 

Hell just use some steel wool and a new 9 volt battery you'll get lots fire as it will set the steel wool on fire.
No joke I had that happen i had some sitting on my desk and just opened a new battery
the steel wool somehow got next to it moving stuff to find something.

Next thing I no the steel wool was on fire, Cant get no safer then that LOL.
Low voltage and maybe 50 mA lol

 

Have a look LOL

 

May I suggest fine as in 0000 steel wool.

Ron