Wednesday, January 6, 2010

We have a winner!

In the quest for a pressure sensor with an appropriate range for my prototype wind instrument controller, the winner is...

The Freescale MPXV4006GP (pdf spec sheet)

With my blow-tube from experiment 6 hooked up to this sensor, through a T connector with half the flow going to the sensor and half dumped, the zero to full response feels pretty natural to me (although I haven't played my trombone in a looooong time). The raw values read from the sensor are about double those of the sensor I used in Experiment 6.

Physical Interfacing

The sensor comes in a package designed for SMD mounting, so I straightened the legs and soldered it to some dual headers.

To hook up the air supply, I attached some heat shrink tubing (unsure of the diameter) to the input port and gently heated it to get a seal.

This tubing, it turns out, has an outer diameter very close to the inner diameter of 1/4" garden drip irrigation tubing, which is what I hooked up to my blow-tube. So sliding the irrigation tubing over the heat shrink and overlapping for a couple of inches makes a good-enough seal.

Electrical Interfacing

  • +5V to pin 2
  • Ground to pin 3
  • pin 4 to analog input of Arduino. Raw input values from the Arduino ADC range from 58 (no blowing) to 1015 (blowing like I'm playing trombone on Varese's Integrales).

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