Hot wire foam cutter

Step 10 Wiring up the transformer and dimmer switch

This photo is your wiring diagram. The black two conductor wire on the left goes to the wall plug, and the brown one on the right goes to the hot wire.

This photo is just to show what connects where. You should of course use the wire nuts that came with the dimmer switch (esp on the 120V connections) and/or tape to ensure that no bare wires touch each other, or you, or your pet. Be careful not to electrocute yourself or start a fire.

Comments

[llulu2]

i have a question. i bought a transformer two thin yellow wires and the other side has black, red and yellow thick wires. how will i know if it's DC or AC . Or rather which wire will i use for connecting the plug in's and to the hot wire? :x need help. :D

[Nawaz]

A transformer is an AC-AC converter. Meaning that you input an AC and will get an AC output but of a different amplitude.A transformer can work both ways. In your case, I would say that you want to step-down your mains to a lower value(example 240V to 12V). In this case, your input will be the two thin yellow wires and the output will be the 3 wires on the other side.

Since there are 3 output wires. It's will be something like 12-0-12. Meaning that if you use any of the left or right wire with the middle wire, you'll get 12V output, but if you use the two outermost wire only(without the middle wire), you'll get 24V.

A bit confusing, but i hope it helped :)

[mikesnyd]

OH ya. and the secondary leads off the transformer are two greens and a green with a yellow line. The two greens are my source of the 24V 2A. and i think the grn/ylw is ground but i am unsure. The schematic it came with didnt even tell me.

[johnny3h]

I have been "fiddling" with electricity for about 55+ years and I THINK that third wire on the output side of the transformer is what is called a CENTER TAP.

A Center Tap is a wire that is connected to the transformer winding RIGHT AT the middle. As other commenters have mentioned, when that wire is used in conjunction with one of the other [end of the winding] wires you get PRECISELY ONE HALF [1/2] the voltage, AND if it is wire "like a ground" on two seperate circuits each connected to ONE of the winding "end" wires you get TWO seperate circuits of one half the specficied voltage each.

If you just use the two end wires then you get the full rated voltage.

Again, I'm an electrical/electronics novice, but this is the way it was explained to me. Hope this helps for novices to understand "Center Tapped" transformers.

By the way, transformers can be ordered with several taps [on both the secondary (output) and primary (input) windings to obtain many combinations of voltages and current outputs].

[mikesnyd]

So i made this wonderfull little contraption you have described. I have a light dimmer and a 24V 2A transformer. I initially had a #10 guitar string as my wire but i broke it and was told to use this 80lbs test fishing line(its steel). Everything was running smooth until about 5minutes of operation. i was in my third cut when my transformer started to smoke. I have not been able to get the thing working again. So do i unwrap my transformer and re wrap it or just go get another one? How may i put a safety catch in there so as to protect this from not happening again? And as for the thrid wire comming out of the secondary side of the transformer.... do i ground that wire? your diagram had this left alone. Maybe i am just lucky enough to have a crap transformer. Have a happy happy day eh. Sweet build man.

[Audiyoda]

On almost all transformers the secondary lines can be configured for full voltage or half voltage. Generally the two same colored wires are full voltage (in your case, 24V 2A - green and green), combining two different colored lines will result in half the voltage (in your case, 12V 2A - green and yellow). You will always have that third line 'free' in a single pole application like this. I always tape it off so as to no cause a short.

*A Transformer doesn't require a ground - your work should still be grounded, but not the transformer.

[guru_florida]

The green wire is typically earth ground, as in attach it to your metal project box ( if used.) The purpose of this wire is if any electrons are passed through it (i.e. if there is any voltage difference between the earth and this wire), it will trip the breaker! It's a safety feature of three prong electrical systems.

There are three wires used in AC, Hot, Neutral and Earth Ground. It sounds like you are using this green wire as if its the AC neutral wire when in fact it is Earth Ground. In DC, we talk about ground being the return path to our electrical circuit, but this ground is not the same as Earth Ground. In the U.S./Canada, AC neutral wire is usually white and black is hot. See the following link for AC color codes:
http://www.allaboutcircuits.com/vol_5/chpt_2/2.html

[izzdawg1323]

so i got all the gear for the power supply. the only difference is the power cable has a green lead which im assuming is the ground. when i plug it all in it kills the circut breaker in the house. i checked for a short circut, but everything seems fine. i made a bow thats 2.5 feet long and it has a 24guage wire. in either case im stumped.. any advise/ideas

[eng.alamin]

how many AMP and Volt is this transformer also did you have cutting lead for RC pane wings am new i alawyas missup :(

[mikeythev]

I measured the current and voltage on the hot wire loop. The 25.2V 2A transformer put out 7 volts and close to 1.5Amps. The current peaks and declines very quickly because the wire heats up quite quickly. To add what was previously commented on, temperature affects resistance a lot.