Need foam cutter power supply circuit advice

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?

Also this is the third time I tried posting this message (over the past two days) to google groups so if there are two other copies that I can't see for some reason I am sorry.

Thanks in advance Brian

Reply to
BrianS
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Brian, A "quick and dirty" method is to connect the output of a variac to a step-down transformer. Use the variac to control the temperature. Inexpensive Variacs are readily available on the surplus market. From a safety standpoint, it's not a good idea to use the Variac output directly, since variacs are variable autotransformers and do not provide isolation from the mains. . I have successfully used nichrome wire for this application. Regards, Jon

Reply to
Jon

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