"Si Ballenger" wrote in message
...
On Fri, 25 Nov 2005 20:48:19 GMT, 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.

The current limiter I saw used a glass pie pan with pieces copper
metal on each side with salty water as the electrolyte. It would
start to steam some when in operation. The furnace was a small
clay flower pot with holes in each side with the carbon rods
sticking inside until they touched.

Exactly-when I was a kid we made them like this all the time. As I
recall, it came from "700 scientific experiments, with
illustrations"...