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    Content by Mika Satomi and Hannah Perner-Wilson
    The following institutions have funded our research and supported our work:

    From 2013-2015 Mika is a guest professor at the eLab at Kunsthochschule Berlin-Weissensee

    From July - December 2013 Hannah was a researcher at the UdK's Design Research Lab

    From 2010-2012 Mika was a guest researcher in the Smart Textiles Design Lab at The Swedish School of Textiles

    From 2009 - 2011 Hannah was a graduate student in the MIT Media Lab's High-Low Tech research group led by Leah Buechley


    In 2009 Hannah and Mika were both research fellows at the Distance Lab


    Between 2003 - 2009 Hannah and Mika were both students at Interface Cultures
    We support the Open Source Hardware movement. All our own designs published on this website are released under the Free Cultural Works definition
    Circuits and Code

    Heat Controlling Circuit

    Here is the circuit schematics to control heating elements.
    I am using MOSFET as a digital switch to control on/off of the each heating element from arduino digital out pins.

    The project I developed this circuit for uses multiple heating lines, therefor I am pulsing it with 100ms each. OpAmp and transistors are there to open the MOSFET switch completely incase pulsing time was not enough.

    !! oops, there was a mistake on the above schematic. I was powering the opAmp with too less power, and pushing the mosFET gate with 5V when it actually needs 12V to fully open the gate. The above schematic configuration will still work since IRLML0030’s internal resistance is very small, but when I replaced mosFET to other kind (STP16NF06), it started to heat up the mosFET since the gate is not fully opening. The revised schematic is following. I have tested this one, and it works with STP16NF06 too.

    PDF download from here>>HeatControllDriver_Schematic.pdf

    The original circuit schematic comes from Gabriel Wegscheider, who is my friend and a hard core engineer:) I am also posting his original schematic.

    And here is some additional comment from Gabriel. “Some (oldstyle-)JFET-Opamps have Problems using input-voltage near GND and produce inaccurate output. So I shifted the low level of the positive input voltage to about 1/3 of supply-voltage instead of GND, thereon I shifted the reference-voltage from 1/2 to 2/3 of supply-voltage. After this correction this circuit should work with all opamps – not only rail-to-rail-opamps.”
    So, if you are using old style OpAmps (I do not know which ones are “oldStyle” though…) you should change that part from this schematics.

    He has also sent me a new version of FET controlling circuit schematics. In this one, TC4427 FET driver is used instead of opAmp and transistors. This way, you can spare out a lot of components.

    The circuit is used to heat up steal based conductive thread which is woven in the cotton fabric. This fabric was developed at Smart Textile Design Lab at the Swedish school of textiles. Here is the first test movie from heating up the woven fabric which has thermochromic ink print on front surface.

    thermochromic heat pattern test from mikst on Vimeo.

    4 Comments so far

    1. Web Developer on February 17th, 2011

      way back my college years I use to research different circuits for my project, I missed the chance of being here. It should have been an awesome project, I miss those days.

    2. sawadee on April 5th, 2011

      Hello,

      Did you use the power supply (5v) only from Arduio?
      Where is the 24v supplied from?

      Thanks

    3. Mika on April 6th, 2011

      24V was supplied from separate ACDC power supply that can provide 2.5A. The ground of the power supply and Arduino’s ground must be connected. I used 24V because the heating element (steel conductive thread) I used requires 15-24V to heat up with the speed I like to have, and it takes 2-2.5A when you apply these voltage. If you use more conductive heating element, probably you need less voltage.

    4. sawadee on April 15th, 2011

      Thank you for the reply.

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