foam cutter power supply circuit advice needed

I need some expert advice on a power supply circuit. Normally I would have asked my friend who was an electronic wiz, but he's just passed away this year so I need a new electronic expert. I know this is probably a lot to ask, but I figured there might be some kind soul who might lend a little of their time. I would gladly exchange what knowledge I have on other subjects such as AutoCAD, Linux, programming, etc.

I want to make a power supply circuit for a foam cutter. I've been researching them on the Internet and found a number of different plans, but I don't know enough about electronics to judge which one would be best and if any of them could be modified (safely) to fit some of the parts I already have. My skills are limited to soldering and following a good set of instructions, not design.

I've found these different designs:

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From the sites I've read many recommend that you do not use nichrome

wire. So I have some stainless steel wire (0.020in DIA) left over from a different project. I have no idea what ohms/foot rating it has. Also I have a working transformer that is 120V input and 12V 8amp output. Most of these designs call for 24V transformers.

My questions are:

  1. Which design do you think would give the best control of the wire temperature?
  2. Can any of these designs work with the wire and transformer that I already have? If so, what changes to the components (if any) would be required?

Thanks in advance Brian

Reply to
BrianS
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WTF? The image links direct to file:///C! Someone really f***ed that up..

Inefficient, but will work. You'll need a large heatsink...

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Phase control, better.

I've heard you can also toss a lamp dimmer on the primary side. It's not recommended to put a TRIAC in front of a transformer but apparently it works.

I wonder why, that's BS.

Two feet length will do it.

None, none of them have feedback from wire temperature to power delivered. They all control voltage or power to the wire.

Well between voltage and wire, for a given temperature you have some amount of volts per length of wire, so that depends on how much wire you want to use. I mean, it should be a duh moment if you consider using an inch vs. ten feet of wire, one's going to get hotter.

Tim

-- Deep Fryer: a very philosophical monk. Website:

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Reply to
Tim Williams

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