# Make a Pencil's Lead Potentiometer (Experimentations)

Here is a really simple experiment in witch you will make a Kind of potentiometer (Variable Resistor) out of a sheet of paper and a graphite pencil (Lead Pencil)... Impossible you think? Check it out!

So first , What is a Potentiometer?
Its not very complicated, to make it short, it's a kind of resistors ( Limit the current flow) but its adjustable, so you can raise or lower the limit of the current flow.

I recently seen a video of MAKE Magazine (MAKE : Present The Resistor) on Youtube in witch they were doing something similar to this and thats where I got the idea to make an Instructables about how to make this simple Variable Resistor.So I have no credit for the idea, I just did an Instructables, to share it with you!

The Idea is to draw a band (with a Graphite pencil) on a sheet of paper ,the band of graphite will act as the Variable Resistor (Potentiometer) because the graphite conduct electricity but poorly.
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## Step 1: Material

Here is what you will need to do your simple Variable Resistor and to test it:

Variable Resistor:
• Sheet of paper
• Pencil [You need a very soft one like 2B+ (Less may not work properly)]

To Test the Variable Resistor:
• Multi-Meter
• an LED
• Alligator clips (2)
• Source of power (9v battery is good)

## Step 2: Draw the Variable Resistor

On the sheet of paper , you will need to draw a band about a centimetre wide and 5cm long and full it up with Graphite pencil. ( You can also try with longer band! ).

## Step 3: Testing with the Multi-Meter

To test your Variable Resistor with a Multi-Meter, you need to set it to the Ohm section(To test the resistance of the Graphite pencil), It work well with 2000k and anything in K.Put one electrode on each extremity of the band and look the resistance on your Multi-Meter, then get the electrode closer and closer and see what happen... Check the video!

hpatel8 says: 2 years ago
cant you just use aluminum foil? Even though- nice experiment.
robot1398 says: 2 years ago
very nice!!!!!!
nutsandbolts_64 says: 3 years ago
Question: Would this work with the graphite replacements for mechanical pencils?
cardboarddude says: 4 years ago

I tried this except i used a motor instead of a led but it doesnt work and I am sure that the motor works HELP!

fruitkid101 in reply to cardboarddude3 years ago
You need to check how many volts your motor needs to run. It isn't working because doesn't have enough power
matroska says: 3 years ago
A simple note to clarify, there's no such things as pencils leads actually made out of lead. Today it's only a mix of graphite and other stuff depending on the brand.
oscarthompson says: 4 years ago
wait a minute... Wouldn't this only work with 'lead' pencils? Stationery store sell pencils with other type of cores...

Thanks

Oscar
agent harmsy in reply to oscarthompson3 years ago
No, because the 'other' cores are graphite, which is also conductive :P
dava_2 says: 4 years ago
Nice, Very Nice!
MrLouque says: 4 years ago
Thats pretty sweet, good work
catfish23 says: 4 years ago
Excellent project, i will try it with some spare electronics parts.
chosenone3 says: 4 years ago
I've done almost same thing with white glue and the thing from batteries (black stuff) when it dries it has good resistance and when you apply water it becomes flexible ;]
ben50001 in reply to chosenone34 years ago
(removed by author or community request)
Patented (author) in reply to ben500014 years ago
I dont care..
Patented (author) in reply to chosenone34 years ago
Heh?
chosenone3 in reply to Patented4 years ago
well its almost the same thing it acts as a resistor but you have to play with amounts of "charcoal"(?)  and white glue to get desired results.

Patented (author) in reply to chosenone34 years ago
Oh ok I get it!
But its not dangerous this black charcoal thing inside the batteries  ?
chosenone3 in reply to Patented4 years ago
I don't think it is but if it is you can use activated charcoal I think.
sodiumcanine says: 4 years ago
GBT-11 Meter! Great model, Mine is nearly 6-Years Old A fuse here battery there has kept it going. McV
afatflatcat says: 4 years ago
Christ on a bike. All this Paper Motor talk has me confused...
xitis says: 4 years ago
doesn't work with me...
Patented (author) in reply to xitis4 years ago
Are you sure your LED is working? did you try to switch the lead polarity on the battery? Check it out and send me back the result !
xitis in reply to Patented4 years ago
the LED is working fine...i tried it on direct lead and it is working but somehow it is not working on paper...
Patented (author) in reply to xitis4 years ago
Ok than whats the pencil your using?
Patented (author) in reply to Patented4 years ago
And are you sure you put enough graphite on the sheet( it need to be very dark , work better with the pencil i mention.
macrumpton says: 4 years ago
if you draw a coil with a pencil and run a current through it does it create a magnetic field? Would it be possible to make an electric motor by drawing the coils?
killrsheep in reply to macrumpton4 years ago
only if you can draw a 3D coil.... and even if you somehow accomplish that (i would imagine it involves a lot of graphite and tons of thin strips of paper) graphite has a massively different resistance than copper does so my wild guess is that magnetic fields generated by a graphite coil are very very very veeeeeery low so in short... no, but it does get you thinking....
macrumpton in reply to killrsheep4 years ago
I imagined you would make the coil 3d by rolling or folding the paper after the pattern has been drawn. Perhaps the conductivity could be improved using the drawn graphite coil as an electrode (or anode I forget) to deposit a more conductive material, say copper onto it with an electroplating process.
BOOM5601 in reply to macrumpton4 years ago
I like the idea.
killrsheep in reply to macrumpton4 years ago
well yeah! that would be better but then it wouldn be considered a graphite coil...i was thinking last night of how could one accomplish a "graphite paper motor" and a lot of problems arised... say we make a dc motor with a colector on the rotor and some magnets for the stator.... i dont think we could fit enough graphite paper windings on the rotor to acomplish any significant torque (not even to move a rotor with zero load so say we make a... farfetched out of my mind "inverse dc motor" so we make a magnet rotor and we wind the stator (wich is a bigger pies so we might... just migt get enough windings) and say we would have to make another shaft to use as a collector for the stator to make a dc alternating current (jut in case we dont want to use any complex electronics.... after all we are making a very.... davinci-esque motor) and then comes the complex way wich is usin some sort of AC low voltage supply... wich is a bit crazier... a lot crazier!... theres a "simple motor design" somewhere around here, it just involves some "magnet wire" (im not sure of the technical english term) a D battery, a rubber band, a magnet and some nail polish i think....... maybe you could make one of those out of graphite... keep in mind tho that even the design that uses the magnet wire on that instructable produces just enough torque to move the "rotor"
macrumpton in reply to killrsheep4 years ago
I think for simplicity's sake a permanent magnet on the shaft and stationary coils is the way to go. An ac power source like a wall wart (one with ac output or you could remove the rectifier diodes) would make it so you did not need any kind of switching mechanism to change polarity of the magnetic field. It might even be possible to have no permanent magnet and have another coil on the shaft with the dc power coming in from the two ends of the shaft. I am having a hard time visualizing what shape the coil(s) need to be. Keep in mind the coils can be printed on both sides of the paper.
killrsheep in reply to macrumpton4 years ago
of course it would be possible... theoretically, but still... let me see if i can explain the way i see it... We need a LOT of windings, on a strip of paper with a very very "impractical" small width, and since we need lots of windings we need to overlap more than twice (wich is what you get if you draw on both sides), that can be accomplished by overlapping layers of paper, but a new problem arises, you have to protect and isolate the coils from erasin or shorting each other or most likely both, wich requires some sort of insulation coating... now back to the "why we would need small widths... a rotor coil doesnt go around the shaft... it goes length-wise, inserted in some slots in the core , i really dont see how can we manage to insert a ring of insulated paper (wich by now turns out to be bulkier and more expensive than insulated copper wire) in a core with at the very least three slots and also achieving a small air gap between the rotor and stator it seems a bit easier to wind the stator, since its bigger, but i still dont know if it would create enough magnetic field... we "are" using a resistive path i really didnt go into it before because it is fun to imagine further than that, but id think there is a noticeable impact on magnetic field when using a resistive path
killrsheep in reply to killrsheep4 years ago
then again... a solenoid is also an "electric motor" a linear one, and i think the coil design is quite a lot easier (im basically against the conventional electric motor bcuz you would need to wind the paper around a laminated core with a few slots on it ... wich just seems quite impossible to me) i think the coil is just a cilindrical coil so it seems like the ideal way to make some sort of solenoid... maybe a needle for the shaft... its lightweight and ferromagnetic so.... i think its worth a try
macrumpton in reply to killrsheep4 years ago
You could make the solenoid drive a crank and flywheel to get rotary motion.
killrsheep in reply to macrumpton4 years ago
yeah that seems like a better way to go, id try to make a very long coil with a very lightweight shaft.... the logic behind that is that i doubt a small scale solenoid would produce much force to move a mechanism, and a linear coil can be made in just about any size with no problems also the shaft so, yeah id try that, make a huge coil and a large lightweight shaft Hey, here's a thought! just so we stop guessing around... make the electromagnet experiment with a paper graphite coil... y'know the experiment where you use a nail, some insulated wire and a battery to make an electromagnet, only this time use a graphite coil... thats one easy way to compare the magnetic field's achieved by both means (wire and graphite)
macrumpton in reply to killrsheep4 years ago
Good Idea! I will try to do that tomorrow.
Kaiven says: 4 years ago
Interesting.. It could be fitted in a small rotating cylinder, kind of like a light dimmer. That would be useful, but does it create heat with too much current? Will the paper catch fire? :P I saw some light dimmers that were pretty expensive just for me to play with electronics, but this could be helpful for small motor gadgets an doohickeys.
macrumpton in reply to Kaiven4 years ago
or make a circular track on a disk.
sageserver in reply to Kaiven4 years ago
light dimmers dont use resistance to dim the lights they use 3 transistors inside them and they work becuase of the ac current thats put into it.
Patented (author) in reply to Kaiven4 years ago
Hey, that seem a very good idea to me! (make a permanent potentiometer)And it would be very helpful and cheap to do! I am going to give it a try, and I give you news!
Kaiven in reply to Patented4 years ago
Ok :D Make an instructable if you can!
Patented (author) in reply to Kaiven4 years ago
I will for sure!.. If it works!!
Kaiven in reply to Patented4 years ago
Good luck! :D
BOOM5601 in reply to Kaiven4 years ago
The only problem would be that pencil leads contain clay, and this could create heat.
Kaiven in reply to BOOM56014 years ago
That's why I asked if the paper would catch fire :P
BOOM5601 in reply to Kaiven4 years ago
Time bombs ;)
Kaiven in reply to BOOM56014 years ago
:O YES!
killrsheep in reply to Kaiven4 years ago
it should work much like tracks on a pcb rite?..... i mean the wider it is the most current it can handle, i think the "pick ups " have to be wider too
thinkdunson says: 4 years ago
a variable resistor is actually called a rheostat. but good instructable.
froggyman in reply to thinkdunson4 years ago
or a potentiometer
thinkdunson in reply to froggyman4 years ago
a rheostat has two terminals, while a potentiometer has three… a rheostat is a variable resistor, while a potentiometer is a variable voltage divider. a potentiometer can be used as a rheostat by ignoring one leg, or shorting it to the wiper terminal (in order to prevent an open circuit if the wiper fails).

HardCoreHacker in reply to thinkdunson4 years ago
osh-kosh in reply to HardCoreHacker4 years ago
Ya, why?
HardCoreHacker in reply to osh-kosh4 years ago
Any one can put stuff on it. It was more of a joke.
osh-kosh in reply to HardCoreHacker4 years ago
oh. good one. the please makes it extra funny.
thinkdunson in reply to HardCoreHacker4 years ago
why
HardCoreHacker in reply to thinkdunson4 years ago
Any one can put stuff on it. It was more of a joke.
thinkdunson in reply to HardCoreHacker4 years ago
yeah, but then when someone puts something on it that's wrong, someone sees it and corrects it. and if people keep putting things on it that are wrong, they stop allowing changes to that page.
osh-kosh says: 4 years ago
This was in Forrest M Mims' book 'Getting Started in Electronics', 26 years ago.
Putzer says: 4 years ago
Foxhole radios operate using this method.
DoItOrDie in reply to Putzer4 years ago
I recall seeing one foxhole radio in which the guy even "drew" the coil for the radio by using the pencil to draw the wire on a long sheet of paper, and then roll it up. I don't remember just how he did it but it worked.
HardCoreHacker in reply to DoItOrDie4 years ago
I made one for a science project a while back
warracer says: 4 years ago
Ben non Nick yer ben nice ton instructable HAHA! jlai recu par email tu vas etre big toi!
Patented (author) in reply to warracer4 years ago
Hehe! Prend don sa comme un défi pis essayer den faire un nice! Pis essaye quoi sois : Featured, Popular pis dans la news letter! Bonne chance!!
robotkid249 says: 4 years ago
Hopefully in the future we have circuits boards made of paper...
alzie in reply to robotkid2494 years ago
Actually, the older style PCBs were / are made by laminating paper with epoxy. Newer style is fiber glass.
BOOM5601 in reply to robotkid2494 years ago
Scientists are currently working on a way to print silicon and other parts directly onto paper. It would make stuff cheaper, but would ruin electronics as a hobby.
macrumpton in reply to BOOM56014 years ago
Actually if you could get an inkjet printer that would allow you to print any circuit you could design including the components it would probably revive electronics as a hobby. There would be huge libraries of circuits that you could cut and paste togther and test in your design program, and then you just print out the result when it works like you want it to. Actually it all exists already except for the printer.
itsthatsguy in reply to BOOM56014 years ago
"but would ruin electronics as a hobby."

I don't think so =) many eople thought SMD would ruin electronics, btu it only advanced us into the world of tinyier things, mpaper should allow for flexible things, which makes electronics more useful in more applications, but even if it were obsolete, i wouldn't give up my electrical "fun".
raniamit110 says: 4 years ago
Cool!
hubi says: 4 years ago
very cool, if u use this in an oscillator, it could get a nice , tiny Soundmachine
geeklord in reply to hubi4 years ago
Like this?
geeklord says: 4 years ago
Did this give you some sort of inspiration?
IW5 Industries says: 4 years ago
i have the same multimeter!
Patented (author) in reply to IW5 Industries4 years ago
Yay!
OBar says: 4 years ago
I had hoped someone would invent something like this I just didn't think it would be that simple. This is very cool.
LuminousObject says: 4 years ago
This is cool. Do you happen to know if the standard #2 pencil is a 2H or a 2B?
AllergicToMilk in reply to LuminousObject4 years ago
A #2 pencil is approximately an HB pencil. Slightly harder if I remember rightly.
Patented (author) in reply to LuminousObject4 years ago
As you can see in the pencil chart in step 1, standard pencil #2 would be an HB hope it help you!
BOOM5601 in reply to Patented4 years ago
2B and darker would be better as they have more graphite for conductivity, but then again it is a resistor.
LuminousObject in reply to Patented4 years ago
Okay, thanks.
Arbitror says: 4 years ago
Make a Pencil's Graphite Potentiometer (Experimentations)
Patented (author) in reply to Arbitror4 years ago
Yeah while I was doing this instructables, I often changed the title but I finnaly put lead because most of people refer the pencil to a lead pencil ... but your write it actually made of graphite
gameboy7oa says: 4 years ago
I've done this before but I made simple circuits. I had to use a 9v to light one led though so its not all that great.
CelticLock says: 4 years ago
Very cool project!
D34th 4n6el says: 4 years ago
this is quite possibly one of the coolest things i have ever seen
ItsTheHobbs says: 4 years ago
Sweet! I saw something like this, only it made noise... It's a really cool concept!
LuminousObject in reply to ItsTheHobbs4 years ago
I think you might be thinking of the drawdio? http://www.instructables.com/id/Drawdio/
ItsTheHobbs in reply to LuminousObject4 years ago
Yes!
unicycle2993 says: 4 years ago
that is quite cool.
ChrysN says: 4 years ago
Cool!