What works best?

Guys,

If I wired batteries to a sheet of aluminum foil and melted plastic on it, placed rubber on one side for grip, and used plastic to cover the whole thing - would that work? I am trying to make a heating pad for class and I thought this would be cool. Basically i know copper is the best for heat conducting because it holds heat the longest, but i want that heat to go to the plastic cover so it can warm food.

I know plastic is an insulator, but is there anything more practical then that - I want it to be able to get wet so I can't use clothe.

thanks in advance

 

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First of all hot plates are cheap enough that you should seriously not consider doing something as dangerous as you are proposing to do.

Second silver is the best conductor of electricity and heat and copper is a good second place. Good conductors heat up and cool down faster, so they don't hold heat the longest.

Considering your ignorance about this subject maybe you should watch 1000 ways to die and then plan on not being a star on that program.

 

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I just flip an iron upside down.

 

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Not sure exactly where the attitude came from...

What I want to do is create one - I understand there are things that work, but what I want to do is find a cheap way to make one. By using a plastic mold around thick aluminum powered through a safe means, it would in effect be a hot plate. I wanted to use aluminum because it would heat up and cool down the fastest - not so much the one that stays the hottest the longest.

Not sure where in this theory I would die? Either way, positive and helpful remarks would be much appreciated.

Thank you, also please try and be more witty with your science humor haha :bawl:

 

He is killjoy the ass clown . Have you heard the good news ? Names have meaning . I think you better look at some schematics first . Then see if you want to do the project .

 

You need to work with ohm's law. For instance, if you would be using a 12 volt battery and your load (aluminum plate or whatever) had a resistance of 2 ohms, that would give you 6 amperes of current. 6 amps times 12 volts is 72 watts - the plate would heat up sort of like a 75 watt light bulb. You can measure the resistance of the load with a meter first. You have to have good wires and connections leading to the heater, because the resistance is so low. Usually a heater is made with a coil of some metal that doesn't burn away - like the element in a toaster.
You aren't going to kill yourself by messing around with this sort of thing, you'll learn something about electricity ( and probably melt a few wires).

 

Probably not. The resistance will be so low that all the heat will end up in your battery, your connections and your wiring, with very little in the aluminum foil.

Get some wire (thin and long) and lay it down in a spiral. Measure the resistance at the ends. If you have a 12 volt battery, and you want 100 watts of heat, you need about 1 ohm total resistance. If it's too low use thinner wire or longer wire. If it's too high, use thicker wire. I'd recommend magnet wire because the enamel on the outside of the wire is fairly temperature resistant, and it can get wet without too much trouble. (And at 12 volts the odds of you getting a serious shock due to lack of insulation is very low.)

I'd recommend about 50 feet of 24 gauge wire, or 10 feet of 30 gauge wire if you want something smaller (but the risk of burning it out goes way up.)

 

Okay,

Thanks for the help/advice guys. So realistically there is no way for me to create one of these that could roll up and be stored like a tube?

 

This forum has a lot of attitude especially towards people doing thing they are obviously not qualified to do (trust me we get a whooooolllleee lot of them)

The problem with your current setup is it may cause a short circuit. Which if you plan on battery power could mean blowing up the battery and spewing acid all over you. Which will not go well in class.

I'm not electrical engineer, but here are my two cents. Take copper wire and find something similar to a large washer (ideally donut shaped). Make sure its metal. And then wrap a ton of copper wire (make sure the wire does not have a rubber insulator covering it, just the naked wire) around the washer like metal donut. Put it in a safe insulator (ceramic plate would work best) and then rest a ceramic bowl inside of the hole (the thinner the walls of the bowl the better), it doesn't have to fit all the way inside, just enough so that it is in contact with almost all of the copper wires.

An even better idea would be to take electrical tape and cut it into inch sized pieces and put them on the wires on the inside part of the donut so that there is improved surface contact.

Use a low voltage battery to avoid having the electricity jumping from one loop of copper wire to the next because that would make a short circuit and that would certainly prevent this from working let alone what it would do to the battery.

That's about it. Although if you want to make it work even better surround the donut shaped heating element with a ceramic "pipe", it only needs to be about 5-12 inches high and to be able to surround the donut while leaving an inch of space between the wall of it and the copper wire.

Then take tin foil and tape it to the inside wall of that ceramic 'pipe', that way it will reflect the heat back onto the ceramic bowl.

Put whatever you want heated up inside of the bowl.

And if your battery starts to heat up disconnect it. If you are really serious enough about this to continue on then here is a possible solution.

1. Connect the battery to the heat plate (that donut piece of metal with the copper wire) with thicker gauge copper wire with an insulator and connect it to the bare copper wire. That should help.

2. Buy some distilled water, ask your parents where to buy some but its like five bucks for a gallon. Fill a ceramic bowl with it. Then pour it down the drain (do not use soap, and try and do not rinse it with tap water, and do not dry it off, its not life threatening to make these mistakes, but it will keep you from having to redo these steps) repeat for two or three times. After that your bowl should be as close to "pure" as we can get it. Put your battery inside of the bowl and then pour the DISTILLED water inside of it.

Water itself is not conductive of electricity, its the impurities inside of it that are, such as salt and other contaminants. By distilling the water you are using the chemists have removed these impurities making it non conductive of electricity. And being the fact it is water means it will help to cool down your battery. The reason I had you fill and empty the bowl earlier was to remove the contaminants from inside the bowl itself.

But for the love of G-d, do not even THINK about hooking this thing into anything larger then a 9V battery and that includes the electrical outlet. It's not my problem if you kill yourself. And no, I have never tried this before. So tell me how it works out, and again, not my problem if you didn't listen to reason and actually manage to put yourself or someone else in a hospital.

 

Sure there is. Get some silicone rubber (very heat resistant) lay the wire in a spiral, glue another layer of rubber on top and then roll it up.

 

Again,

thanks for all of the help - I am truly a novice and I appreciate the explanations and especially the concern in the given environment. I do not want to undertake anything that would cause harm.

My question is if Silicone Rubber is Heat resistant, wouldn't that hold in the heat of the copper wire? I want a material that will allow for the most heat to be let out up top, and a material for the bottom that would keep the most heat going upwards vs. down towards a table.

I just want something that can roll up for my experiment. I will have someone who is more knowledgeable design the electric part, but I just want to design the main piece.

Help is always appreciated!

 

How hot do you need it to get?

If you want something you can roll up...how about a heating pad?link

Here's one for 13 bucks.

You would have a hard time heating up a piece of aluminum foil with current. It's so thin with so much surface area the heat would dissipate almost immediately. I just heated a couple of pieces of chicken in the oven on aluminum foil, and removed it with my bare hands.

 

Wont the copper wire eventually break after rolling it up so much?

Question: IS there a type of liquid I could put inside of it so I basically could just have the copper wire running through it and some liquid that would heat up with the copper wire or is that just not possible? Trying to use less copper? Idk I am just thinking outloud

 

Pk,

What is the application for this? How hot do you need to heat something and what? This would help tremendously in helping with your design.

 

I want it to get to about 85 degrees.

I want to make it 1 foot by 1 foot. Trying to figure out how much wire I need and to make sure that whatever I cover the copper wire with, I want to make sure that gets warm.

Basically how much copper wire will I need and how thick?

From there would using some liquid help to keep the the pad hot?

What should I use as the pad? Silicone Rubber or what? - Remember I want this to be able to roll up

 

No offence..but you are trying to run before you learn how to crawl. You clearly have no knowledge about the basics of electricity...yet you want to create something without that knowledge.

I don't want to discourage you..but sometimes it's better to use established technology, rather than try to create it yourself with no knowledge.

 

Well, your first mistake is using copper wire for a heating element. A _much_ better choice was discovered a very long time ago. It's called nichrome (a nickel chromium alloy). It is readily available. Just look around for a scrapped toaster. Or buy a cheap one at your local Walmart.

 

I think I am trying to run before I learn to crawl here. I need to get a crash course in the basics of electronics.

What would be a good place that I could quickly get up to speed on how things works in basic terms and then further entrench myself deeper?

Thanks again for all the thoughts - A lot of things make sense, and I appreciate the teaching lesson you have all given

 

Question:

If I wanted to have tubes running on the ground that would basically be cooling pipes (about 1/2 thick), what material would I be able to put on top of those tubes that would protect it if a car were to drive over it? AGain, realizing that the cold tubes would then make this material cold. I want it to be something flexible, not necessarily a steel sheet.

Any ideas?

 

Hello pkerrigan21,

It would be a great help to those offering assistance to you if you could share the purpose of what you are designing.

Unless you are attempting to design something that is a prototype and you are concerned about having your idea stolen.

I am not sufficiently skilled in electricity to assist you with that project, but with your subsequent one, with cooling pipes, I ask you, WHAT are you trying to accomplish.

1. What kind of ground are you putting these pipes on?
2. How much pipe, how large an area are we discussing?
3. What kind of pipe are you thinking of using?
4. What are the temperatures of the ground?
5. What is your source and temperature of water?
6. Are you planning to recess these pipes or just lay them on the ground?
7. How heavy is the car or vehicle you are planning to drive over it?
8. How often are you going to be driving over this set-up?
9. Why do you mention flexibility as a requirement?

Unless one has some idea of the overall intention, one cannot provide the optimum suggestions for the circumstance which is challenging you.

My advice on the electrical project would be to do some more research.

That which you need may already exist, and if you want to build one from scratch, have you already done a search on the net?

It is admirable that you have such a strong creative channeling, but you will be of more use to society if you survive the learning curve.

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Do listen to the fellows and be almighty careful about how much electricity you play with, okay? Wouldn't want you to become a stat.

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