Using 13v to pwr conductive thread acting as heating element on several circuits

I am looking to use an arduino and sensor to control a circuit which regulates power to open power lines (conductive thread). The open power line is sewn into a piece of fabric covered with thermochromatic ink, which responds as the thread heats up.

I have tested plugging in a 13.3v power into the vin and gnd, and have connected the thread. I was wondering how I could use the arduino to control several lines separately (from an input—button, sensor, etc).

I assume I would connect all lines to the common ground and then have separate pins connected to each parallel circuit, but I'm pretty sure the pins only communicate data, not power? Do I need a shield which can regulate the power to each of these circuits to control when they receive power?

but I'm pretty sure the pins only communicate data, not power? Do I need a shield which can regulate the power to each of these circuits to control when they receive power?

Right. The I/O pins Arduino put-out 5V at 40mA or less.

How much current do you need? Or, if you know (or yiou can measure) the resistance you can calculate it using [u]Ohm's Law[/u].

You can build driver circuits for each separately-controlled thread or you may be able to use a multiple-driver chip.

[u]Here[/u] is a MOSFET motor driver circuit. In this circuit your threads would share a common power supply and they are powered/controlled through the negative "ground" side. (With a resistive load you can eliminate the diode.)

The open power line is sewn into a piece of fabric covered with thermochromatic ink, which responds as the thread heats up.

Have you tried this without the Arduino? It seems like the heat will be concentrated around the thread and it might give a "small" effect. And, that's assuming you can get enough heat to get temporary color-effect but not enough heat to get a "fire effect". :D

to open power lines (conductive thread).

In electronics terminology, "open" means no-connection. For example, if you open the connection to a light bulb, no current can flow and the light will go off. Although sometimes the connection should be open, such as when a switch is turned-off, when somebody says "open" they are usually referring to a fault.

The opposite of an open is a "short". i.e. If you short the two wires to the light bulb there is no resistance through the bulb, excess current flows and you blow a circuit breaker. Again, most of the time when people say "short" they are usually referring to a fault, but sometimes someone will say, "You forgot to short the grounds together".

"How much current?" is really the most important question here. If these are relatively small, like 40-100mA then an LED driver chip would work well. Particularly if the segments are different lengths and need constant-current regulation.

A MOSFET is good for higher currents. Milliamps to hundreds of Amps are possible with relatively small MOSFET transistors. Use an N-type MOSFET and connect all the threads to the positive supply voltage at one end, then to separate MOSFETS. Drive them from the PWM pins on your Arduino for fine control. Make sure the MOSFETS all connect back to the ground side of the high-voltage supply with a good fat ground wire.

See http://www.electronics-tutorials.ws/transistor/tran_7.html

Hey guys, thanks for your help—and for the verbiage clarification.

So I used a regular power adapter to start with, as an initial test:

This worked (no fires! :slight_smile: ), but I wanted to check the amount of voltage needed for a certain speed of change. I got a selective power adapter and it came to around this (14V, 0.64A):

The reason I wanted to use an arduino, is I have experience using it with a kinect (via processing), which I wanted to try to use to control this circuit.

DVDdoug:
Right. The I/O pins Arduino put-out 5V at 40mA or less.

How much current do you need? Or, if you know (or yiou can measure) the resistance you can calculate it using [u]Ohm’s Law[/u].

You can build driver circuits for each separately-controlled thread or you may be able to use a multiple-driver chip.

[u]Here[/u] is a MOSFET motor driver circuit. In this circuit your threads would share a common power supply and they are powered/controlled through the negative “ground” side. (With a resistive load you can eliminate the diode.)
Have you tried this without the Arduino? It seems like the heat will be concentrated around the thread and it might give a “small” effect. And, that’s assuming you can get enough heat to get temporary color-effect but not enough heat to get a “fire effect”. :smiley:

In electronics terminology, “open” means no-connection. For example, if you open the connection to a light bulb, no current can flow and the light will go off. Although sometimes the connection should be open, such as when a switch is turned-off, when somebody says “open” they are usually referring to a fault.

The opposite of an open is a “short”. i.e. If you short the two wires to the light bulb there is no resistance through the bulb, excess current flows and you blow a circuit breaker. Again, most of the time when people say “short” they are usually referring to a fault, but sometimes someone will say, “You forgot to short the grounds together”.

This is a common issue with translations to/from English. In English we open a tap to turn it on, but close a
switch to turn it on. Just say “on” and “off” to avoid all confusion.

got a selective power adapter and it came to around this (14V, 0.64A):

So that would be using a FET then, that is a significant amount of current.

I am most certainly going to make sure I get an electronics for dummies book for my birthday.

So are these the kind of MOSFET that I want?

So are these the kind of MOSFET that I want?

No.
You need a logic level FET, one that turns on fully with a 5V signal.