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Would it be possible to make a cold heat toaster using pencil graphite strips? Answered

I am thinking of making a bread toaster using graphite rods which would heat up when a high current is applied to them. How would I go about doing this? What voltage would I need to use to supply it?


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Best Answer 11 years ago

I think that lardbob is referring to the Cold Heat brand soldering iron (similar to this), which briefly sends a large voltage through a graphite resistor. The idea is that because the tip is so small, it can rapidly heat to a solder-melting temperature and then rapidly cool down to a skin-safe temperature. (I do not own one, so I do not know if it actually accomplishes this goal.)

You certainly could use an array of thick graphite rods running on wall current. (I would use a lightbulb or a fuse in the circuit as well, for safety.) But as orksecurity points out, graphite is more fragile and decomposes much more quickly than other heating elements.

Another problem you may encounter is that the water escaping from the bread keeps it too cool to toast properly. Water absorbs an enormous amount of energy as it turns into steam, which helps keep the temperature of the remaining water close to the boiling point. To overcome this problem, you may need a fan to force hot air quickly across the bread.

Also, you could try letting a quick spray of baking soda solution dry on the surface of the bread before toasting. Browning happens more easily at high pH.

If you want to experiment with instant toasting, I suggest getting some nichrome ribbon, a strong computer fan, and a computer power supply (or other regulated power supply).


11 years ago

I'm not sure why you think this would be "cold heat"... As a kid, I was able to set pencils on fire by hooking my model train transfomer across them. Of course the thermal cut-out on the transformer kicked in pretty quickly; as you say, this draws a lot of current. Graphite is fragile. There are good reasons commercial toasters aren't made this way.