All you electronic buffs come here!

So I need a little help with my hot wire styro foam cutter and looking for advice

I need a 120vac to 12vac 3a power transformer any ideas where i can salvage one from? I also would like the ability to switch from 6vac to 12vac

I also have this transformer out of an old crt tv but I cant find any info on it here are some pics will this work? the board it is attached to says 250v all over it so i am not sure that it will work lol

is there a good way to test a power transformer?

here are the pics

thanks for the help




this transformer looks old and frankly knackered, I can see signs of overheating on the first picture.

Try looking at an old PC AT transformer there are many voltage options there. check youtube for connections.
My favourite option is Power Supplys, you know like a power supply for a printer etc. I know they are often DC but your heater will work just as well.
Another option is China I found this transformer.

I agree with @NealRobinson, looks overheated.
I have a couple of 12V switching power supplies, as per Neal’s link, for anything needing a low voltage, 30A output, cost about @25 - $30. A lot safer too.

@AngusMcleod

hey angus would you happen to have a link for a good power transformer for this project?

Have you thought about using a small model RR transformer. You can find them very cheap.
I’m sure you must have seen the Nichrome Wire Calculator .

http://www.jacobs-online.biz/nichrome/NichromeCalc.html

So I found a 12v 40 amp with 3 amp charge battery charger will this work for my project can someone help me on this to get it up and running

Please list what you have as a start.

Then make a list of what you wanna do.

Most of all dont try to “test” the transformer unless you know what you are doing, in theory you can unleash 1000v++ through your body if you connect it the wrong way.

@NealRobinson
@AngusMcleod

alright so here is what i have

x1 12vdc power supply rated for 40 amp max with 3 amp charge
x1 piece of kanthal wire various gauges

here is what i want to do

I want to have a adjustable styro slicer I want to in theory adjust the temp of the wire

Here is what i have done so far I have hooked up my power supply on the 3 amp side to the kanthal and I get a pretty good effect but its a little hot the wire just barely glows red but it actually cuts the foam pretty decent if you cut it semi quickly

I measured the temp of the wire at I believe 500 degree F I need to adjust it down just a tad

how can i do this

@AngusMcleod

and i realize that 40amp is a bit much but your not going to produce anymore amps than the load that you have on the power supply so if you exercise caution it will be completely fine even 300mA and less can kill you

@AngusMcleod

give me just a second I will take some pictures and I did something to make it cut perfect lol it might be redneck though lol hold on

The cut on the left is with the fan and the cut on the right is without the fan so I need to cool down the wire to get a cleaner cut

@AngusMcleod

Cant I just use a rehostat to lower the temp of the wire?

I wish I could use the ac light dimmer I bought for this project but I dont think that will work will it?

yeah it has all of that so how would i regulate the ouput?

would that work

http://www.kicklighting.com/PWM-dimmer-switch-for-LED.htm