For those who don't know, a thermopile is simply a bunch of thermocouples connected in series, which allows them to generate more voltage than a single thermocouple ever could.
Simple enough right.
So what is a Thermocouple?
A thermocouple is a device that produces a small voltage when there is a temperature difference between a pair of conductors. Make a bunch in series and you have a thermocouple.
I am going to show you how to make a thermopile out of about a foot of copper wire and four paper clips. I want you all to know that this will not generate very much electricity. It is not some miracle cure to the worlds energy crisis. It is not much more really than an interesting experiment for people who like this sort of thing.
I can't think of many practical uses for this particular design, you could use it a some sort of measuring device perhaps. Maybe in conjunction with an Arduino, you could perform some sort of output based on a candle flickering....an LED that will light if the candle burns out (and the voltage being generated by the thermopile drops)?
You would have to design something much more stable and made up of many many more thermocouples to generate any usable amount of power.
Step 1: Gather Stuff
- some solid core copper wire
- four paper clips (perhaps more depending on the length of your paperclips when straightened)
- a small tea-light candle
- a glass receptacle ( to hold the candle)
- some play-doh or similar
Tools that you will need or that will help
- soldering iron
- a muti-meter
- wire cutters
- needle nose pliers (for straightening out your paperclips)
- a third hand vise
Step 2: Thermocouple
A thermocouple is made by connecting two different metals, with one metal between two samples of the second metal. If one of the two conjunctions is warmer than it's opposite side,a small voltage is generated
Certain alloys and metals are much more efficient than others, but a simple one can be made out of some copper wire and some paperclips.
If you also want to make a thermocouple, you will need another paperclip and about an two inches of copper wire (less is fine too).
Just solder a length of copper wire between two short lengths of paper clip wire. (You will need to straighten out and clip lengths from your paperclips, we aren't making a rocket so it is not overly crucial to make thinks pin straight, you just want something that you can work with.)
If you connect the two ends of this to a digital multi-meter, and warm one of the two connections with a lighter, you will be able to detect a tiny voltage. I got a millivolt (0.001 volts)!
How exciting was that eh! I know, I know, but we are just exploring here.
So what happens when we connect a bunch in series?
We get a thermopile!
Do we get more voltage?
Lets build one and find out!
Step 3: Build a Thermopile
We know that a thermopile is a bunch of thermocouples connected together. By making it into a star shape we will be able to heat only one side of each thermocouple by using a candle in the center of the star.
Begin by straightening out your paper clips and your copper wire as well if need be.
You will need eight pieces of copper wire and eight pieces of paperclips cut to roughly 1 and 1/2 inches long. Again, we aren't building a viable generator, but rather testing a principle.
Once you have your pieces cut, you can begin soldering them together. Take a look at the finished thermopile below to have a good idea where you are headed. A technique that worked well for me was to flip it after each weld and solder one side always with a steep angle and the other with a wider angle.
Have a look at the pictures below to get a clearer idea.
These are both soft wires and you will be able to gently bend it into shape at the end, so don't be to critical on yourself if your star is less than perfect. Mine was far from perfect and worked perfectly to illustrate the principle, so yours should work fine for that too.
When you are all finished, you should have something that looks roughly like the the one in the picture.
Now you can go and get your glass candle receptacle from the freezer.
Light your candle and place it centered in the glass.
Secure your thermopile in place on top of the glass with a little bit of play-duh at each junction. The idea here is to keep the cold side as cold as we can. Otherwise the heat conducts to the outside joint and the two equalize and we lose our voltage. This keeps the cold junctions cooling, while the hot junction is warming.
Take your readings and be amazed! I was able to generate a whopping 0.012 volts! See how high you can get yours to go.
One thing that helped me generate a little bit higher voltage was gently blowing the flame, causing it to dance enough to be able to sort of equalize the heating of all the hot junctions.
So there you have it. Thermocouples and thermopiles!
Exciting stuff eh.
Share and enjoy.