In article ,
Al wrote:

In article ,
Paul Keinanen wrote:

On Thu, 24 Nov 2005 18:49:24 -0500, Jon Yaeger
wrote:

Take apart a couple of D cell carbon-zinc batteries.

Wash off the carbon rods. Put each in a wooden clothes pin and connect the
attached ends to the mains voltage (US customers only, please).

The problem is that the carbon rod conducts heat quite well, so after
a while, any wooden object will catch fire :-).

Tap the free ends of the rods together. Move them apart as necessary.

You must have quite slow fuses in 110 V land if you can do a reliable
ignition without blowing the fuse. For 230 V operation, I would
suggest using a current limiting resistor (such as a large heater) or
an inductance (such as fluorescent light ballast) during the ignition.
When there is a solid arc, the current limiter can be shorted out.

Paul


I would put a 100 watt lamp in series thereby limiting the current. I
would shave the ends down to points so they heated up rapidly. I put
them into a hollowed out fire brick and made a cheap furnace. Of course
don't look at it; it's like looking at the sun.

PS: I was 16 at the time ;-)

I used a 0.5 or 0.7 mm pencil lead gently torqued down across the
terminals of a regulated DC power supply. Set the current limit very
low, crank the voltage up all the way and increase the current limit
until the center of the lead starts glowing red. Due to the heatsinking
effect of the binding posts, the lead will always heat up the most in
the center, then the carbon will start to evaporate and the remaining
lead will gradually neck down in the center until it is glowing white
hot. As soon as the lead breaks in the middle, you convert from
incandescent to carbon arc lamp, which usually surprises everybody
watching. The arc is good for about 5 seconds until the voltage drop
across the arc exceeds the capability of the power supply.