Hi,

I'm working on a simple project and have run across a problem. Been a long time since I've done circuits and cant seem to get this problem solved.

I need a simple circuit that when a switch is flipped it will produce a spark over a 3mm gap. Does anyone have an idea on how to do this? I've tried creating a simple/modified marx generator to create the spark but still no luck.

Been using:
1 Mohm resistors
4kV 102 pF Capacitors
9V Battery

Thank you,
kevin

 

Given the voltage and the capacitance, the energy stored in the capacitor is 40 nano-Joules. I'm sure it is not enough to jump the gap. The dielectric strength of Air is 3 MV/m or about 9000 Volts for the 3 mm gap. I think you are a ways away from that level.

 

Thank you for the advice. How might I go about changing the circuit? I've tried putting multiple capacitors in series... up to four (4) of the 4K capacitors but still no spark. Is my charging voltage too low?

 

How is a capacitor supposed to create any spark? It will never make more voltage than the 9V you are putting in. You need a transformer or inductor to create any sparks.

 

Thank you kubeek.... I think that is what I am missing.

 

Try this.

 

Thank you! Sorry for my ignorance... I haven't done a circuit design since college. So what I need is the transformer to charge the capacitors. I'm thinking of using 3 AAs battery and this transformer.

http://www.mouser.com/Search/ProductDetail.aspx?R=760390014virtualkey51110000virtualkey710-760390014

Could anyone take a look and let me if they think this would work with my 3kV capacitors?

 

How is a capacitor supposed to create any spark? It will never make more voltage than the 9V you are putting in. You need a transformer or inductor to create any sparks.

I had to google the Marx generator as I had never heard of a passive DC voltage multiplier; It relies on the input voltage being high enough to reliably produce an arc so a 9V input is a non-starter.

If the TS just needs big sparks;

http://www.ebay.co.uk/itm/Boost-Hig...225?pt=LH_DefaultDomain_3&hash=item5d578158e9

 

I had to google the Marx generator as I had never heard of a passive DC voltage multiplier; It relies on the input voltage being high enough to reliably produce an arc so a 9V input is a non-starter.

If the TS just needs big sparks;

http://www.ebay.co.uk/itm/Boost-Hig...225?pt=LH_DefaultDomain_3&hash=item5d578158e9

Thank you!

 

Marx generators work by charging capacitors in parallel and discharging them in series. This is how you get a higher voltage out than what you put in.

In order to use a 9v battery to charge the capacitors, you'll need a driver circuit along with the transformer. You cannot run a transformer on DC.

 

If you don´t need such high voltages, you could try having a look at this http://en.wikipedia.org/wiki/Voltage_multiplier

 

Blocco's idea of the Boost Step-up Pulse Power Module High-voltage Generator is exactly what I need. I was over complicating a simple solution. Didn't know this device existed.

 

I di

Blocco's idea of the Boost Step-up Pulse Power Module High-voltage Generator is exactly what I need. I was over complicating a simple solution. Didn't know this device existed.

I didn't know it existed, either, but it looks scary to me! 40KV on some tiny little hook-up wires? The diameter of the winding wires must be microscopic. Treat it gently. I don't think it will survive much abuse.

 

So #12 gives me another noob question....

If I want a spark to last something like 0.1 seconds (or just a small amount of time really) then stop for like 1.0 second then make another 0.1 sec spark... then repeat over and over until a switch is hit. Is there an easy way of doing that?

 

I di

I didn't know it existed, either, but it looks scary to me! 40KV on some tiny little hook-up wires? The diameter of the winding wires must be microscopic. Treat it gently. I don't think it will survive much abuse.

I have a couple of these modules and I can confirm that they are terrifying, but I haven't manage to destroy one yet.

Lower voltage modules are also available:

http://www.ebay.co.uk/itm/New-DC-3V-to-7KV-Boost-Step-up-Power-Module-High-voltage-Generator-1PCS/251541077786?_trksid=p2045573.c100033.m2042&_trkparms=aid=111001&algo=REC.SEED&ao=1&asc=29479&meid=9c8ffe9335154039a5f41c08e0cf390f&pid=100033&rk=4&rkt=4&sd=251875437450

 

So #12 gives me another noob question....

If I want a spark to last something like 0.1 seconds (or just a small amount of time really) then stop for like 1.0 second then make another 0.1 sec spark... then repeat over and over until a switch is hit. Is there an easy way of doing that?

It's called an astable oscillator. Easily done with an LM555 timer chip. You will need to add a current carrying transistor to provide the 2 amps your module needs and you have to let it cool off enough. It is rated to run for 5 seconds before overheating but no mention of cooling time required. I don't think a 10% duty cycle would work. Too much heat.

 

It's called an astable oscillator. Easily done with an LM555 timer chip. You will need to add a current carrying transistor to provide the 2 amps your module needs and you have to let it cool off enough. It is rated to run for 5 seconds before overheating but no mention of cooling time required. I think a 10% duty cycle would work, but lack of specifications makes this a guess.

Thank you, reading up on it now. Looks like this might work.