Hi, I am showing my nephew some basics in electronics. I, too, am a novice. So I wanted to show him the wires of a toaster glow. I laid out 2 screws on 2x4. Wrapped some nichrome wire around both posts. Ran a 4 double A battery cell to each end. It heated up. Just barely. No where near glowing. So I must need more power. MORE POWER, arr aaarrrr aaarrrrrrr. Lol. So I ran a plug to each end. After disconnecting the battery cell, and attaching the plug. I plugged it in. Should be a real simple circuit. Get the nichrome wire red hot. But instead, just blew the fuse instantly. So I must have too much power going to it. What can you tell me to get this simple project working ??? Anything is appreciated. Thank you in advance.

 

Ummm, you just made a direct short and with 120VAC, *Kaboom*.

Have you looked up the resistance of nichrome wire? Or measured a few inches, to determine ohms per inch?

I have a power supply that I can carefully increase the current (or voltage) to determine how much current you’ll need.

I once did this myself. Experimentally with a three inch piece of nichrome from a toaster and a 12V transformer, I could get a hot glow. Enough to burn through fishing line and burn sulfur.

 

Hi, I am showing my nephew some basics in electronics. I, too, am a novice. So I wanted to show him the wires of a toaster glow. I laid out 2 screws on 2x4. Wrapped some nichrome wire around both posts. Ran a 4 double A battery cell to each end. It heated up. Just barely. No where near glowing. So I must need more power. MORE POWER, arr aaarrrr aaarrrrrrr. Lol. So I ran a plug to each end. After disconnecting the battery cell, and attaching the plug. I plugged it in. Should be a real simple circuit. Get the nichrome wire red hot. But instead, just blew the fuse instantly. So I must have too much power going to it. What can you tell me to get this simple project working ??? Anything is appreciated. Thank you in advance.

Actually, what you have done so far is a very useful demonstration and learning activity to do with your nephew -- and you are drawing the right conclusions.

You wrapped "some" nichrome wire around the posts. They key is that it was just "some" length, as opposed to a carefully determined length.

For the length you chose, the batteries could not supply enough power to the wire to do more than barely heat it up (and, if they could, it wouldn't have lasted for long because the batteries would have quickly been drained).

But, for the length you chose, the increase in voltage by a factor of 20 or so was too much power.

So, like the story of Goldilocks, there is likely a voltage somewhere between the two that is just right.

But instead of trying to find a way to apply that intermediate amount of power, another way is to try to find the right length of wire.

The wire is nothing but a resistor and a resistor is something that when you apply a voltage across it, a current will flow through it. The power dissipated in the resistor is the product of the two. If you put two resistors in series (so that current enters one end of one of them, flows out the other end and into one end of the second, and then out the other end of the second and back to the supply), the resistances add and the total voltage across both is the sum of the voltages across each -- but both have the same current flowing through them.

So now consider your length of nichrome wire as a particular resistor. What happens if you make another just like it and connect them in series? Well, to get the same current as you had before, you would need twice the voltage since whatever you apply splits between the two resistors. If you keep adding additional segments you will need to keep applying more and more voltage to get the same current.

The same is true going the other way. If one length of wire is too short and, when you apply a particular voltage (say from the house outlet) it draws too much current and blows the fuse (or more likely a breaker), then adding an additional length of wire will cut the current drawn in half. That may or may not be enough to keep the breaker from tripping. But if you keep adding length to the wire, eventually you will get a total length that is long enough to heat to the temperature you want without tripping the breaker.

To get idea of the length you are looking for, consider the total length of wire you see down inside a toaster.

Now, before you continue your explorations, be sure to give some thought to the safety aspects involved. There are a couple. If you succeed, you will have a nichrome wire that is hot enough to burn the wood you are using. If you take that into consideration, you will be fine (i.e., assume it will catch fire (it probably won't unless you keep the power to the wire for a long time) and prepare your setup accordingly). Also keep in mind that it will get hot enough to seriously burn you or your nephew if you accidentally come into contact with it or anything close to it. The fact that you are playing around with household power also presents safety concerns -- if you or your nephew get tangled up with that circuit while power is on, it could be lethal. I would recommend always unplugging the apparatus when you are working on it and use a switched outlet to energize it. Plug and unplug it only when the switch is off and be sure that there is a safe distance between you and the apparatus when you turn the switch on. Also assume that sooner or later you are going to do something that is going to cause some part of your apparatus to catch fire or throw sparks. Plan accordingly -- having a small fire extinguisher nearby is not a bad idea, though you probably won't ever have to use it.

There are better and safer ways to conduct these kinds of explorations, but few of us here can't say that we didn't do similar things (and with far fewer precautions than I've recommended) in our childhood -- then again, few of us here had any right to survive our childhood.

 

Have you considered just looking through the slots in the top of the toaster? If you can find a low voltage incandescent bulb such as a flash light bulb or a small lamp for lighting inside and automobile you can easily demonstrate the making of light.
As @djsfantasi so elegantly put it, "Ummm, you just made a direct short and with 120VAC, *Kaboom*." The *Kaboom* would come when you become part of the circuit. And its really painful when lucky to escape death. Please stick to batteries.

 

Hi johnson77

When you can, Google George Simon Ohm.

Not that you could eventually work with him but he became famous by doing things like you describe but more carefully.

Some members here know him very well.

Avoid mains at any rate and keep that nephew that probably admires you, safe

 

Hopefully, your nephew was watching over your shoulder as you were conducting this experiment.
He would have learned a useful lesson as well.

Ask yourself, do you have enough knowledge about electricity and electronics to be demonstrating this to another person?