Principle: an on/off switch cuts off or allows electricity to pass through beyond the switch to its destination (like electric fan, radio, AVR, ref, etc.).

Imagine a plug. It has two prongs, because electricity needs a positive and a negative to work. Without the other, it will not work.

For simple explanation, check your AVR. The portion from the plug. Flat cord is usually used so you see two cords stuck to each other as one.

plug prong 1-------------->to switch-------------------->to AVR

plug prong 2------------------------------------------------>to AVR

When you push on the switch, a mechanism inside will touch the cord from the plug side and the AVR side which makes the circuit CLOSE...to make electricity flow.

When you push off the switch, that same mechanism detaches from the same cord terminals which makes the circuit OPEN...to stop electricity.

If the power supply that you have (refer to Styro Cutter post) has no switch, this is how you can add one.

I'm a firm believer of recycling. I also don't spend on something I can make unless the time incurred is much more than the money I'll have to shell out.

Other facts: I'm crafty. I'm poor. I'm resourceful. Styro cutter is expensive (the flatbed type, whatever that's called, I meant NOT the handheld one which is VERY limiting). Locally, if I remember right, it costs around PhP3,000 at National Bookstore. That's too much for me. Why buy when I can make one?

What you'll need:
1. old pc power supply (like from the 486s or even 286s where the PC itself no longer works, normally because of the motherboard, but the power supply still does). Ok, for those who wonders which is the power supply, it is the one with a metal box inside your CPU case and has a fan.

2.  a piece of scrap plywood 1/2inch thick and about 14x14inches of area. The important thing is the surface must be smooth, good as a 'table' to slide your styro around.

3. a flat iron bar (try the junk shop if you don't have any around) about 24inches long. You'll have to saw a slit with a metal saw about an inch at one end of the bar as if cutting it lengthwise.

4. a guitar string #2 (steel). This one needs to be brand new but it's just about PhP10.00 each.

5. 2 i-inch screws.


Procedure:

1. Bend the metal bar at 4inches (starting from the other end opposite the slit) and 13inches turning inside so you'd be forming a squarish 'J' when you finish. Drill 2 holes equally distanced within the 4inches portion (approximately at 1st and 3rd-inch marks. Use a drill bit for metal, of course, the size not bigger than the screws you'll use.

2. With the plywood lying on the table (as if your drawing board), attach the iron bar to the plywood. The part where you drilled holes will be perpendicular to the top of the plywood (at the center) that the part where you sawed a slit will be almost poking your nose. Much like attaching a "handle" to your board.

3.  Drill a hole on the plywood that's just right below where the slit end of the metal bar is. That's where you'll insert the guitar string with the locked end at the metal bar. The loose end will be inserted through the hole on the plywood and that will be where one terminal of the power supply be.

(I think I need to show pictures. It's rather difficult to explain it in layman's terms. The pictures have to wait, though, until I get hold of the styro cutter which is rather somewhere I can't reach out at the moment atop our vertical shelf.)

To technical people here is the simple explanation.

1. Choose the  cable set that's supposed to be connected to the floppy drive (others can do, but for ease of explanation, I chose the floppy drive supply). Black is always negative, right? There are 2 other colors. Mine here is yellow and red. One is 5 volts, one is 10 volts. If you have your multimeter, you can check out which is which. If not, try the two and choose the one that heats less. 10 volts is just too much, so you need the 5 volts supply. (Don't forget to set your multimeter to DC at higher than 10volts.)

2. Attach one end of the supply (negative) to the guitar string and the other end (positive 5V) to the metal bar.

3. The guitar string is removable from the metal bar slit which cuts off the current. When it's back, it heats. That's when you're ready to shape your styro.

4. For making holes through the styro like letters O and A, etc...poke a hole on the styro with a pencil perhaps, then insert the guitar string through it before you insert the guitar string back to the metal bar slit...shape your letter.

It is best to have a power supply with a power switch. If yours does not have one, just pull the plug.

Or, you can add your switch...you probably have one lying useless with your screws and nails and hardware stuff...well if you're technical, you know how to connect the ends, right? You don't??? Ok, I'll make it another post....