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I’m building a Blendophone for Maker Faire. What’s a Blendophone? It’s a “musical” instrument made from eight blenders controlled by an iPhone and an Arduino. My friend Usman Muzaffar is writing an iPhone app to control the beat sequencing and solo input, while I’m building the hardware and an Arduino sketch to switch the blenders on and off.

The first challenge I had was controlling blenders from an Arduino. I decided to go with the PowerSwitch Tail, which is a neatly packaged isolated AC relay circuit that can be controlled from a 5V DC signal — very safe, very easy. The PowerSwitch Tail draws about 40mA of current to do its thing, which is the limit of what an Arduino digital pin can reliably push. In practice, I found the Arduino could usually control the PowerSwitch Tail on its own, but would occasionally fail to trip to relay. To be safe, I decided to create a driver circuit for each of the eight blender outputs. I created a drawing of the circuit in Fritzing, and then prototyped it on a breadboard.

Once this was working, I made things a bit more permanent. I used a ProtoScrewShield to solder the eight transistor circuits, and provide eight screw terminal pairs for the output to the PowerSwitch Tails. This works great, and gives me a nice solid connection to the blender controls. You could also use a standard MakerShield and a ScrewShield to do the same thing.

In the next installment I’ll talk about making this system wireless, using XBee radios.

In the Maker Shed:

Makershedsmall

PowerSwitch

PowerSwitch Tail

John Edgar Park

John Edgar Park

John Edgar Park likes to make things and tell people about it. He works in CG animation at DisneyToon Studios and writes for Make, Boing Boing, and other places online and in print. You can find him at jpixl.net and twitter @johnedgarpark — if you like that sort of thing.


  • http://pulse.yahoo.com/_3X4RESQP6C4YYIFQMYU2Q63ZB4 AndrewS

    probably the worst project yet!
    wireless blender orchestra!
    so why is it wireless? thats useless?
    blenders? yep blenders so its not music its just noise and stupid
    power cord relay things? x8? well someone has too much money and not enough brains!!

    • Anonymous

      @john park – delete andrew’s comment, what a troll.

      • Anonymous

        Done.

      • Anonymous

        Done.

      • Anonymous

        Done.

      • Anonymous

        Done.

  • http://www.facebook.com/david.seitz David Seitz

    Andrew, 
    I get the feeling you don’t understand the spirit of MAKE.
    It’s not always about usefulness, sometimes it’s just to see if you can.

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