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Make a Pencil's Lead Potentiometer (Experimentations)

Step 5Testing With LED - The Test

Now that you have your assembly, touch one end of the band with the other alligator clip and the LED lead on the other end of the band and slowly make the 2 connection closer and closer, see what happen... (*IMPORTANT* Avoid touching the LED lead directly on the battery pole or you can burn it up! You can also add a resistor in the circuit to avoid any damage of this kind) Check the Video! I made the Video a bit darker so can so the LED glowing! Explanation: The reason why the LED is glowing is because the current from the Positive pole of the battery ( Black clip) flow through the Lead or Graphite band and complete the circuit to the LED, result; the LED is glowing. Now the reason why the LED get brighter when you get the black clip nearest is because the Lead have some resistance [(Doesn't conduct electricity perfectly)(Measured in Ohm)]. So the closer you get to the LED, the less resistance the Lead provide you so more current go to the LED and make it brighter!

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14 comments

Nov 15, 2009. 11:59 AMdava_2 says:

Nice, Very Nice!

Nov 11, 2009. 6:59 AMcatfish23 says:

Excellent project, i will try it with some spare electronics parts.

Oct 11, 2009. 1:14 PMchosenone3 says:

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 ;]