Electrical Saftey/Transformer project

[Zambini]

I am making a transformer for my physics class and I need to know all the safety info I need. Besides coat everything with a thousand feet of electrical tape and always keep things unplugged when working on them.

I just bought a 120V Primary to 16V Secondary transformer, and measured .64A (AC)

Now, I am just assuming, but this is clearly more than enough to kill me, is it not?

I am going to make a power transformer, so I just need to make it go from like 16v down to 5v or something just to show I know what I'm doing.

So i asked her if I could just use an iron bar, and she said that would work.

So here is what my plan is:






not shown is the encapsulment i will somehow build around it. Probably made out of plastics coated with thick-ass layers of electrical tape.
She's got lots of plastic boards I could most likely use.

So what do you guys think? and what precautions do U suggest

[Lead Head]

The transformer windings use insulated copper wiring. Any exposed metal contact the primary side should be covered in electrical tape. While 16v isn't terribly dangerous, its always good to exercise caution.

Remember to use insulated copper wiring for your iron bar transformer. It may be a good idea just to give the iron bar transformer a thin coat of electrical tape just incase there happens to be a fault in the insulation and someone with hands soaked in salt water decides to grab it

EDIT:

Its not necessary to use THAT much insulation on the iron bar transformer, If you do it right you'll have 16v and 5v running through insulated copper wiring, which basically takes 99% of the risk of getting shocked out right there. But even though its not that dangerous, do NOT get reckless.

Remeber this, it only takes 10 miliamps to stop your heat, but ONLY if the electricity finds away to penetrate the body. Lower voltage such as 16 and 5v usually cannot penetrate the skin very well, unless your hands are wet with a very conductive fluid.

[Dread]

16v @ .6 a is not enough to kill a healthy adult, but it is enough to lay you back on your gluteous maximus. Still be very careful when working with any live device.

You do know that the coils create an electromagnetic field that must overlap for the transformer to work right? Wrapping the coil on opposite ends of a iron bar may not give you the result you are looking for. May I suggest that you use two iron bars placed parallel to each other (and very close) | | <--so that the EMF overlaps.

Pri. - Sec
Coil-Coil
# of # of
--Wraps--
50 - 15.62
100 - 31.25
150 - 46.87
200 - 62.49
250 - 78.11
300 - 93.73

:) 250 (or multiples of) will get you closest to 16v stepped down to 5v.

You also won't need to coat a plastic box with electrical tape.
And I would recommend using wire nuts for the connections rather than electrical tape for many reasons, number one being safety. Electrical tape is not as good as a lot of people think.

[Zambini]

Wait, so i gotta use INSULATED wire? Damn her and her lies.
And I gotta use a box' shape? DAMN HER AND HER LIES AGAIN!

lol

Ok, so if I get 2 bars, I can do something like this:

[Lead Head]

Originally Posted by Zambini

Wait, so i gotta use INSULATED wire? Damn her and her lies.
And I gotta use a box' shape? DAMN HER AND HER LIES AGAIN!

lol

Ok, so if I get 2 bars, I can do something like this:

Well I think the right word is lacquered wire, its similar to insulated wire except instead of PVC insulation, its lacquered, usually thinner to. Not sure on price. Usually one of those $10 desk fans from walmart or target have motors with quite a bit of wire in them

[Zambini]

What about this thing I have here called "Magnet Wire: Insulated" (24 guage 100 feet)

thats lacquer all right. lol. We used this stuff in physics to make a motor.

Good thing I bought it :)

[Reloadron]

Originally Posted by Zambini

What about this thing I have here called "Magnet Wire: Insulated" (24 guage 100 feet)

thats lacquer all right. lol. We used this stuff in physics to make a motor.

Good thing I bought it :)

Magnet wire is what you should be using. Next, though electrical tape will work the best tape to use would be Kapton Tape. Just using an iron bar would work, not the picture of efficiency due to permability issues but it will work. Additionally, think about how this works. Dread pointed out how the magnetic fields overlap.

Typically you don't use the same gauge for the Primary and Secondary winding. Not that you can't just not generally done that way. Maybe I missed it but do you know what you want your secondary to output? The Primary of what you will make will use 16 Volts. Thus do the math and get your turns ratio of Primary to Secondary. Never mind I see refrence to 5 Volts.

You know the maximum current you have from your store bought transformer. (BTW no at 16 Volts 650 mA is not going to likely hurt you, however use good safety practices). Be careful when connecting a plug or whatever to the primary of your store bought transformer. The 120 VAC from a US wall outlet can cause you to have a really bad day as in Fatal under the right conditions. Just apply good electrical safety practices throughout.

A good core if you can find one would be an iron ring.

If you have time and would like some Kapton Tape just PM me, I will be happy to send a roll to you.

When calculating your turns ratio remember to take into consideration your 16 Volt source. The resistivity (rho) of your hand wound primary figures into your available current. That will be a function of the wire gauge you use on your primary. I saw refrence to AWG 24 which has a resistivity of about .0302 Ohm/Ft.

Arghhh, time for me to think about getting to work...

Ron

[Zambini]

Yea, I don't know what voltage I will use, and I can always go back to fry's and get a different gauge if its really important.

Really all I need to do is demonstrate that I understand the concept of building a transformer.

So once i find an iron square thingy, i'll put it together and post pix

[Reloadron]

If this is just a simple exercise in how a basic step down transformer works the wire gauge is not that important. Likewise if the actual output is not that important then you can keep things real simple. Something like 16 Volts (Approx) in on your Primary and 4 Volts (Approx) out on your Secondary would afford a nice 4:1 turns ratio, meaning for every 4 Primary turns you have 1 Secondary turn.

Your main consideration with the turns is making sure the priamry has enough turns you don't cook your wire. Note the resistance of the wire used. Make sure you have enough turns to get the overall Primary resistance above where the actual current draw will not exceed the ampacity of the wire you use.

Ron

[Zambini]

This is for another phys project, but when a 9v battery reads 7.14 volts, it's considered a dead battery, right?