Introduction: 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.
Step 1: Material
Variable Resistor:
- Sheet of paper
- Pencil [You need a very soft one like 2B+ (Less may not work properly)]
- 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
Step 4: Testing With LED - Assembly
You can also test the Variable Resistor with an LED. Here is how to do it: First connect your 2 alligator clips to the 9V (one on each pole), then connect the Negative clip to the negative lead of the LED, and finally, bend the positive lead of the LED(Anode, the longest) so its easy to move on the paper and it gives good contact. ( If you don't have any alligator clips, you can replace them by normal wire, simply twist around the components to make the contact, or solder ) *Tips : If you don't know witch lead of the LED is - or + , test out with a button cell !
Step 5: Testing With LED - the Test
Step 6: Experiments!
Try wider or longer lead band or try other patterns and see what happen..! Try with other conductors like metals or anything else you know! Try with other kind of pencil (2H, 2B...) Try colouring lighter or darker for different result! Experiment, Experiment, Experiment ! and have some fun!!
Hope you enjoy !
91 Comments
Tip 3 years ago on Step 6
Very nice!!!! Add to your experiments Ohm's Law V=I * R. Voltage equals current times resistance. If you vary the resistance at 9 Volts from the battery what happens to the current in amperes when you measure it at different points of your pencil mark?? Does the amperage change? Measuring the volts at different points along your line - Does the voltage change? Your input voltage is 9 volts from the battery. Does Voltage and Amperage and resistance measured follow Ohm's Law?
7 years ago
Thanks.
This will help me in a few experiments.
11 years ago on Step 6
cant you just use aluminum foil? Even though- nice experiment.
12 years ago on Step 6
very nice!!!!!!
12 years ago on Introduction
Question: Would this work with the graphite replacements for mechanical pencils?
13 years ago on Introduction
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!
Reply 12 years ago on Introduction
You need to check how many volts your motor needs to run. It isn't working because doesn't have enough power
13 years ago on Introduction
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.
13 years ago on Introduction
wait a minute... Wouldn't this only work with 'lead' pencils? Stationery store sell pencils with other type of cores...
Thanks
Oscar
Reply 13 years ago on Introduction
No, because the 'other' cores are graphite, which is also conductive :P
13 years ago on Step 5
Nice, Very Nice!
13 years ago on Introduction
Thats pretty sweet, good work
13 years ago on Step 5
Excellent project, i will try it with some spare electronics parts.
13 years ago on Introduction
I dont care..
13 years ago on Step 5
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 ;]
Reply 13 years ago on Step 5
Heh?
Reply 13 years ago on Step 5
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.
Reply 13 years ago on Step 5
Oh ok I get it!
But its not dangerous this black charcoal thing inside the batteries ?
Reply 13 years ago on Step 5
I don't think it is but if it is you can use activated charcoal I think.
13 years ago on Introduction
GBT-11 Meter! Great model, Mine is nearly 6-Years Old A fuse here battery there has kept it going. McV