In Stofftrykksalen Anders has made a circuit with Arduino that you can borrow to test out the conductivity of materials (see the image). For instance when you want to make strechable sensors like Elin’s knitted garment with conductive thread.
Just switch the LDR light sensor that is conected now for your garment/knitting/++.
Just connect the arduino to your computer for getting power. A program is already uploaded to the board where a sensor on analogue pin 0 (zero) is dimming a LED on PWM pin 9.
The circut is described on the tagged page in the «Getting started with arduino» book and uses a standard analogue in pwm out program.