PC2 - a week of trials

After a week of hair pulling and grim determination I think we have success. The two big aims for the week where making a touch sensor that works (this is a black art at best) and figuring out some way of heating up an area approximatly 10cm square.

The touch sensors are grounded plates of alfoil with a small, insulated area that is attached to an intergrated circuit that messures capaciatance and thus generates a signal when the sensor is touched. These started the week being complicated paper and alfoid affairs that provided intermitant success and then failure. But, de dammed the consiquences, we went on to produce a prototype jacket with all touch sensors attached - it didn't work to well but we learn more about the layout of the jacket and more about why the sensors didn't work.

So back to repeating the sensor protyping. Come thursday and its not looking so good - the jacket it pretty much an arial or dead to the world as fair as sensing touch goes. So we pack it in and go home. But today turned the corner, maybe, we made a good touch sensor today. Based on what an other group did and a simpler design it seems to work pretty reliably - no interferance and no random reads. Perhaps it will be good.

Today also brought some success with creating heat. When the Jacket is touched back heats up and we needed some means of doing this. We bought some heat wire some time ago in an attempt to produce a result from it. Heat wire is thing, uninsulated wire which gets warm when a current is passed through it. We've managed to produce some resuslt out of a small peice of wire but today produced a different solution to this problem.

We're using a very low resistance transistor to switch current accross the heat wire useing the PWM port in the Arduino. This works fine - but the transistor gets very hot (even hotter than the wire) and it has a metle backing So it occured to me that we should ditch the wire and just use the transistors heat as the heat source. So by attaching a heat sink made from folder copper sheet a reasonable are of mettle can be made warm with less fuss than the wire. This idea has still be tested with a larger plate but i think it could work with a plate which is around 6cm square.

Anyway we'll see. Appologies to those that read this and think I'm mad Its late and the end of a long week Cyas.d