Saving a bricked phone with a pencil lead

[stompyonos] bricked his Samsung Captivate. Not wanting to be without a phone for a while, he researched a fix online and found shorting a pair of pins on the USB port would put the phone into download mode, saving his phone. The only problem for this plan is [stompy] didn’t have any resistors on hand. Instead, he came up with a wonderful MacGyverism using a piece of paper, a bit of graphite, and a pair of paper clips.

The process of unbricking a Captivate requires a 300 or 330 kΩ resistor across pins 4 and 5 of the mini USB port. This can be done with a few resistors, but [stompy] only had a multimeter lying around. After scribbling a good bit of pencil lead on a piece of paper, he attached two paper clips to make a variable resistor, dialed it in to about 300 kΩ, and cut up an old Nokia charger for its USB plug.

Not bad for a very easy fix that didn’t cost [stompyonos] a dime, and certainly better than a $500 paperweight.

Paper touchpad

If you don’t mind getting your fingers a little dirty you can replace your mouse with a piece of paper. [Dr. West] made this touchpad himself, which measures signals at the corners of the paper using four voltage dividers. The paper has been completely covered with graphite from a pencil (which we see in hacks from time to time), making it conductive. The user wears an anti-static strap that grounds their hand, allowing an Arduino to calculate contact points on two axes when a finger completes the circuit. See this controlling a cursor in the video after the break.

[Read more...]

Better resistors from a pencil

Many of us here in the office (myself included) can’t tell the difference, but the audiophiles out there who want the best sound from their resistors should check out [Troel's] write-up for making your own non-inductive graphite resistors. Graphite resistors have the traits for being non-inductive, have a negative temperature coefficient, and supposedly sound better. We liked the detail of his tutorial and how he gives many examples for making your own graphite resistor.

[Thanks Maxime]

Making a cold heat soldering iron

cold_heat

Cold Heat soldering irons are pretty cool. They heat up in seconds and cool down just as quickly. [photozz] shows us how we can make one from stuff we probably have sitting around right now. Cold Heat soldering irons work off of resistance, the tip material heats very quickly when electricity is passed through the two halves. Upon assessing what he had lying around, [photozz] realized that graphite would work much the same way.  He modified a regular soldering iron with a new two piece graphite tip, and powered it with an old pc power supply. The end result is quite nice, though it still needs some kind of temperature control.  You may recall seeing other electrical uses for graphite, such as making quick and dirty light.

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