Build Your Own Hotplate

Introduction: Build Your Own Hotplate

About: My whole life I have thought of ways to make things that you can only go out and buy, follow me and I will teach you how to make all sorts of things. Praise carbon!

Here's a situation, so your driving down the road and being you, you get distracted by the beautiful scenery. As a result of this you realize they you forgot to stop at the gas station on your way home from a long trip. You Run out of gas and as it slowly gets darker you realise that the nearest town is 20 miles away. It becomes apparent that you will need to survive until help arrives. How will you get food? How will you purify water?

Here's another situation, it's nearing the end of the semester and you need to study for finals. You sit down, fueling your little study session is a nice hot cup of coffee. Halfway through your coffee gets cold and gross tasting. What are you going to do, waste precious study time to make more while dumping out the old stuff

Both those situations can be solved with a simple, portable, and effective tool that is a must have for anyone who may need something heated up at any given time.

anders625 here with another DIY project that is as much fun to build as it is useful. This project requires some items that you must purchase off the internet, I will add links for those so you won't need to search vigorously for.

I hope you like this one, be sure to subscribe to me for many more instructables like this one coming soon, also if you like this then be sure to favorite it. If you have any questions or comments then be sure to leave them below, I'm very good at responding and if I don't right away then just be patient and I will respond to you soon. Please be sure to vote for me, thank you.

Step 1: Tools and Materials

Here's what you need:

  1. Thin sheet metal, this will make the body of our hot plate. The metal can be purchased at your local hardware store.
  2. A 9volt battery and a 9volt battery clip for power and to make it portable.
  3. A 10k risistor
  4. A red and blue LED (optional, only serves as an indicator light and to make it look cool)
  5. Potentiometer (this will be used to vary the temperature, but if you don't want to vary the temp then you can cut out the potentiometer)
  6. A switch to turn the circuit on and off
  7. A breadboard with jumper wires (this is optional and is only needed if you want to test the circuit before you make it)
  8. You will also need paper and a pencil for designing the case.
  9. Glue that can stand extreme temperatures
  10. The most important item you will need I called a Peltir thermo electric cooler and can be found here on Amazon.
  11. Wire


  1. Soldering iron
  2. Solder
  3. Tin snips for cutting the sheet metal
  4. And wire cutters

Step 2: Designing the Case

here I have my design for the case. in the first image I have put measurements on one of every line and the lengths of the others are determined by tick marks shone. The second image I choose not to right the dimensions because I was hoping the first image would be enough to give you an idea on the size. The first image is the lid and the second image is the body (in case you haven't figured that out all ready).

Step 3: Paper Template

next you will need to cut out the paper design and put it together to make sure that every thing is up to spec.

Step 4: Paper Model

wow, it looks even better then I could have ever imagined. This is how mine looked, if it doesn't look good don't worry this isn't the final product. After all If at first you don't succeed try, try again.

Step 5: Drawing on the Metal

in this step we will be tracing the final paper design onto the sheet metal. I found that it is easier to hold the paper down with tape while tracing, also be sure not to rub the pencil marks because this will remove them.

Step 6: Cut Out the Metal

now you can cut out the metal using the tin snips. Be sure to wear gloves and googles as the metal can be sharp.

Step 7: Form Box

now in this step we will fold and glue all the tabs to complete the casing. You can use tape as a clamp to hold everything in place while you glue.

Step 8:

this is what it should look like when it's done.

Step 9: Building the Circuit

Here is the circuit on a breadboard to give you an idea of what it's supposed to looks like if you do decide to test it. I also drew up a scamatic for you to look at.

Step 10: The Cooler

In this step we will glue on the cooler using the high temperature resilient glue. I would like to also tell you about the awesome abilities of the coolers, when electricity is applied to them they do two Things. On one side they produce a ton of heat. On the other side the they produce extreme heat, in fact these are used in refrigerators to produce that cool temperature that I'm sure we all know. Another cool thing that these things do is produce electricity. Hold a flame to the hot side and it will produce about 6v of electricity, and hold an ice cube to the cold side and you guessed it, it will also produce electricity.

Step 11: Carbon!!!!!!

now because I love carbon I decided to put a big C on the side, and on another side I cut a holes for the switch and the potentiometer.

Step 12: Building the Electronics

now we will build the circuit. Start by soldering the switch to the positive side of the battery clip.

Step 13:

Now add the potentiometer to the switch.

Step 14:

Take the LEDs and solder them together through a wire, then on the one positive LED pin that dosent have a wire add the 10k ohm risistor.

Step 15:

on the spot where the potentiometer connects to the switch, solder the 10k risistor to it so the leds can light up when the switch is turned on, and solder the other end of the LED wire to ground.

Step 16:

now solder the positive end of the cooler to the potentiometer ant the negative end to ground.

Step 17:

now take some tape and cover up all the connections so the circuit dosent short out.

Step 18: Now Your Done

now put everything in and secure all the pieces with glue and you're done. Now when life throws the cold your way you are better prepared.

I hope you like this one, be sure to subscribe to me for many more instructables like this one coming soon, also if you like this then be sure to favorite it. If you have any questions or comments then be sure to leave them below, I'm very good at responding and if I don't right away then just be patient and I will respond to you soon. Please be sure to vote for me, thank you.

DIY University Contest

Third Prize in the
DIY University Contest

Formlabs Contest

Participated in the
Formlabs Contest

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Participated in the
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    Question 3 years ago on Step 18

    Do you have a schematic diagram of this using 12 volts?


    5 years ago

    can you please tell me the theory and the working principles behind this hotplate

    Pure Carbon
    Pure Carbon

    Reply 7 years ago on Introduction

    I respect your respect for my respect for carbon. Thanks for leaving a comment.


    Reply 6 years ago

    I respect ruagaqbuw's "lol" for the respect of respecting the respect of carbon...


    6 years ago

    this is a great way to start a fire.


    6 years ago on Introduction

    you'll burn up the potentiometer long before you get to boiling temperature. you might want to use a pwm driver on a higher current source such as the car battery to run this.

    Just for the hell of it im going to make a REAL instructable on a REAL peltier hot plate, i was planning on making a heater/cooler eventually anyway.

    Ill show exactly how the physics behind it work and exactly what is needed to boil water, and in general base everything on actual physics and truth.

    I seriously hope you consider altering your guide and remove the lies that this boiled water. I would even go so far as to call you out to upload a timelapse video of your device bringing water from room temp to boiling temp, with a thermometer in the picture to show the temp over time. It would be impossible no doubt without defying the laws of space-time.

    2 pieces of advice you missed.
    1, unless its a lithium, and/or your cup is made of highly conductive material it would take hours to heat water up. maintaining tempurature however it most certainly could do off a couple watt power supply, but realistically, given a 9v battery has less energy than your typical AA, this wont even warm water up.
    Second, your peltier wires should NEVER be allowed to bend. peltier plates are ceramic and stupidly designed. it is soldered directly to ceramic semiconductors and levers on the corners of the plate, for the first centimeter at least the wires need to be glued flat, parallel to the plate, otherwise it will break which is bad, it creates allot of resistance and can cause the nearby wiring to burn.

    If you changed this to allow connection to some 10w+ power supply then it would certainly be going somewhere

    Pure Carbon
    Pure Carbon

    Reply 7 years ago

    Thank you for the advise, but how do you know that it won't heat up water? Have you done this exact project? I can assure you that this does work and it can not only heat up it can boil it. The temp. That water boils at is 212°F and this Hotplate can heat up to above 250°F. Coffee mugs (like the one that I used to test it) are excellent insulators and is why they are used as containers for hot liquids to prevent the user from being burned. However , the bottom of the mug is very thin and allows heat to travel through it easily. You also said "your peltier wires should NEVER be allowed to Bend", isn't that what wires are supposed to do. I know that you ment the location where the wires connect to the module, but they are not soldered to ceramic semiconductors. When these are made they use a special semiconducting alloys (metal) that allow heat to be produced when an electrical current is applied to it. One more thing be for I go, if 10 watts was applied to this small module it would over heat, short circuit, and ultimately be destroyed. Here's a tip for you or anybody else who reads this comment, before you make a comment questioning a project do some research, test it, and then judge it, You just might change your mind.


    Reply 7 years ago on Introduction

    actually i have tried it which is why i made the comment.

    Also, the logic here conflicts with the laws of thermodynamics

    For instance, thermodynamics dictates that it takes 4.2J of energy to raise one gram of water, by 1 degree. Hence, 4.2J/mL/C

    a standard mug will contain aproximately 300ml of fluid, which is going to be at least 95% water so it can be asumed to be all water.
    now, in order to raise the water temperature by 1 degree, that would take 4.2x300 = 1260J
    to raise it by a reasonable amount, say to 60-70 degrees, which is hot but not boiling, good for tea and coffee, that would take at most, 50 degrees increase from room temp, so, 1260Jx50c = 63kJ

    Here is where logic seems to have been twisted. You see, at the very best, an alkaline 9v battery will have a capacity of 500mah, which equates to a total of roughly 16kJ, in extreme cases a lithium one might have 1A (9wH) which is 32kJ, but thats not nearly enough
    furthermore, your fighting against thermal loss by dissipation, your heating a mug which is extremely inneficient as its an insulator any way you look at it, the bottom of the mug is always the thickest also, since thats the only part which receives any kind of impact so you wouldnt be able to raise waters temperature by 50 degrees even if you realistically had 100kJ, since your heating a mug through cardboard which has terrible thermoconductivity.

    This of course all even asumes the 9v battery will output normally until its completely dry but the voltage will likely drop beyond useability in the final 20%, i tried with a 300ma nimh just now and the plate only stayed above 60 degrees for about 30 seconds, but thats a cheap 8.4v battery

    Now, this would definitely work to keep a mug hot, no doubt, but not to heat it up. not unless you have a copper/aluminium bottom mug with 10ml of liquid and you wait half an hour since 9v batteries can only output a maximum of 1A, they are only a stack of button cells after all.

    Now, about bending the wires, i didnt say that the bismuth junctions were ceramic, it actually resembles more of a metal, however it is very brittle and may as well be glass, i speak from experience having accidentally found out how easily these plates break, being very frail, especially at the corners. the ceramic plate material holding it all together isnt particularly strong either, at the corners at least.

    when it breaks internally, it reconnects forming a bad connection which can and did burn my wires, or rather melt over 10 minutes of turning on and off with each disturbance.

    As for your statement saying 10W would cause a short circuit, thats nonsense, asuming your peltier cooler is half decent it will have the capacity to take at least 5A, its a brand name one so i dont know its specs, however even the cheapest $2 plates come at 5-6A at 12v. so in general, the plate will survive 10W, i boiled water on mine at 100W, but that required careful controlling as these plates shouldnt ever go beyond 125 degrees, practically speaking 100 degrees is the limit for indefinite use.

    i have however seen some cheap nasty ones made from copper/nickle alloy or even lead, in the lower power ones, but they are really uncommon, i couldnt find them if i tried, not that ide want to, bismuth based ones are the most common and realistically the best for the cost.

    To summarize, i have personally done this and it didnt work, i tried it simply for arguments sake and raised a beaker of 20 ml by 5 degrees using a current of 9v 1A for 30 minutes, the best possible scenario for your hotplate. borosilicate glass doesnt conduct the same, true, but this is a small factor.
    This hotplate can work, but not off a 9v battery, the peltier, if it is something like a tec1-2706, can operate at 100W, and should take 3-4A for heating up water.

    if the supply isnt regulated and the peltier is overworked the internal semiconductor array will warp and tear its contacts apart, making it cease to work.true, so the plate needs a thermostat in that case to make sure it doesnt go very far over water boiling temp, as your very close to the maximum temp there.


    7 years ago on Introduction

    Best dream-to-reality project I have seen!

    So cute - congrats on the win!!


    Reply 7 years ago on Introduction

    You are totally welcome!

    I voted for you in the other contests, I hope you win them too!


    7 years ago on Step 18

    This is a great idea! I have a couple of questions. With the items you used on this instruct,can you boil water? Could you tell me the exact items used? What glue for heat resistance, When I used your link for the P thing, a lot of items came up. I am not well versed in electric things. I just love this idea,in case of breaking down on road. Thank you so much for sharing this.