Feasibility of making a touch sensor with e-textile

Projects General Guidance
1

Hello Everyone!

I'm new in this forum and I need some advise about this new project.

I am a developing an e-textile by weaving conductive yarns with other non-conductive (traditional) yarns. The idea is to touch the conductive parts of the pattern and switch on and off some LED strip.
Being a e-textile project, the obvious choice is Lilypad/Flora, but I'm not sure if it is the best fit, since this is not a wearable project. I actually don't want to use any batteries, just regular current, it is meant to work as a lamp, so I also need to turn on a strip of at least 30cm.

What would you suggest?

Thanks in advance!

Mara

2

Yes you can make a touch sensor even one that has multiple selections by weaving your wire in a 3.3v - input# - 3.3v - input# and so on like that then use a 100k ohm pull down on the the input#s feed that to a transistor and use the output of it as the input to the arduino. You can have as many as you have inputs and since its gonna be in lamp id use and UNO for this. Also use transistors or MOSFETs to drive the leds. There are web pages that will calculate what resistor you need for the LEDs.

3

I would use a UNO.

Sounds an intresting project.

4

Thank you!
What are the advantages of using UNO instead of Flora?

5

The flora a cool device by the UNO is 16 MHz works on 5v and has more I/Os

6

Mara:
What are the advantages of using UNO instead of Flora?

If you are not going to wear it then the Flora as no advantages over the Uno.
The Uno is mush easier to make repeated connections to.

7

In many forums they recommend 1 megohm resistors to start trying for an absolute touch sensor, should I get 1/4 watt or 1/2 watt?

8

Another thing. would a transistor like this one work for a led strip or around 1meter?

thanks!

9

should I get 1/4 watt

Yes, getting 1/2 watt is some what silly as there is no way you are going to exceed the power dissipation.
Watts = Volts * Amps.
So for 1M across 5V the amps you have is 5uA that means the resistor will dissipate:-
0.000025 watts so a 0.25 resistor is safe by a factor of 10,000 times so I think you are save enough. A 1/2 Watt would be safe by 20,000 times, not worth it is it?

Yes that FET will work with the logic levels out of an arduino.

10

Hello!
I got a 1000mA DC adapter with a max of 12v output, and it works fine with a short LED strip, however, I'd like to know what is the maximum of LEDs I can turn on.

Will it work for a 150 diode strip or is it too much?

Thanks!