The gap between a thunder cloud and earth is basically a capacitor.

They have to make the lightning conductor straps on the sides of buildings fairly sturdy, otherwise they'd scatter in millions of molten metal globules when they get struck - sometimes they do melt.

There were plans to use supercapacitors in cars for energy recovery during braking, they could heat a wire for a short time - probably longer if you control the discharge rate with a hefty buck regulator.

Did you think there was some "set in stone" maximum size a capacitor could be?

What rating of capacitance are they?
Do they not meet your expectations?

 

no need for capacitors. have you used a soldering gun?.100/120 watt rating should do. just connect the ends of your wire to the gun where you would normally connect the tip of the gun then,squeeze the gun on and watch your wire glow. you could even light a cigarette with your glowing hot wire.

 

You could alternatively use a much thinner wire. Less mass to heat up means it can get hotter during the limited time you have power from your capacitor.

 

Hot enough to light paper/dry leaves[/QUOTE:
Have you heard of matches? They work well with paper and dry leaves.

 

Is there a way that quite slowly discharge a capacitor. So i want to get a 40V capacitor, charge it the hook it to a button and short it (Not a good idea.)
So as you press the button it will short the cap and the wire will heat up. This is possible with a 9V battery but a cap can hold more voltage. Basically all I need is a simple diagram that shows a good way to slowly discharge a capacitor.

Thanks

Use a large 10 watt resistor to slowly discharge your capacitors, This will discharge them slowly, the actual resistance needs to be high enough to discharge it slowly but NOT too high or it will take forever..... try some out until you find what is best for you.....

 

Energy is not current or voltage. A capacitor will discharge current over a short period of time. A battery will do it over a long period of time, by comparison.
The difference between a battery and a capacitor, is that the capacitor will discharge the current very quickly. The wire will get very hot, very quickly with a capacitor. It will get warm, but for a longer time with a battery.
The same energy, different period of time.

 

Energy is not current or voltage. A capacitor will discharge current over a short period of time. A battery will do it over a long period of time, by comparison.
The difference between a battery and a capacitor, is that the capacitor will discharge the current very quickly. The wire will get very hot, very quickly with a capacitor. It will get warm, but for a longer time with a battery.
The same energy, different period of time.

You need to review the amount of time a battery can power a 1k resistor and discharge time for many sizes of capacitors.

 

Re post # 23, consider as blasting cap, a fine loop of Ni Cr wire of around 5 ohms fires well with cap. discharge in I ms. ' do not remember sizes of C or V, started with 300 V dry cell, 1950's down to 63.5 V ( ? ) later, maybe 300 uF. Flash paper is easily ignited for demonstration.

 

When I first started reading this post I was under the assumption the thread poster wants a delay rate in the realm of hours. But from what it sounds to me like the post is asking is that he wants to use a charged cap as a power source, press a button and do some sort of work with the energy without the sudden complete collapse of the capacitive field energy. In short, I think he just doesn't want the arc that comes with shorting the leads of a capacitor.

[edit]

Forgive me brothers, I read some of the posts too fast. Sounds like the post wants to build a fire starter. Using a very high capacitance and a very small wire one COULD start a fire by heating a simple wire. NiChromium wire has a natural resistance to it that is much higher than a copper wire. I'd think that all he'd need to do is increase the length of wire until he gets the results he wants.

ME? I'd just take a 9 volt battery and some steel wool. Tap the wool to the battery terminals and let the fibers heat up. Then drop the glowing embers onto my fire bed.

Just a note about keeping the capacitor charged and ready for the service: First, it won't hold the charge for a very long time. In fact, a charged cap can lose its potential energy in 10 minutes, depending on the type of cap. THEN there's the fact that - if he doesn't get ignition the first time the capacitor will be spent and not likely going to start any fires later.

Well, the brightest ideas DO start off as a concept. Then the kinks get worked out, and eventually you end up with a light bulb.

 

The question of the OP was simple, and the answer is just as simple: let it sit. Then, like many other one-shot, new members, the question changes. Then we're told that voltage and current aren't energy.

How about an honest question, and acceptance of the honest answers?

If you're shopping for the answer you want, post your <disparaging term removed> on Facebook.