24 Feb 2002 hudson   » (Master)

I've posted images of the homebrew 3D rate sensor built with the Murata gyros scavenged from two Gyropoint mice (for the autopilot project). There is room for the two ADXL202-EB's, too, but I need to order another one. There is a top view and a angled view.

The rate sensors are soldered onto Radio Shack PCB's and connected to a quad opamp (also on a RS PCB). The circuit looks like this:

                  |    \
  Reference ------| +   \
                  |      >----+------  Output
  Gyro -/\/\/\-+--| -   /     |
         R1    |  |____/      |
               |              |
               |     R2       |
               |              |
R1 is 10k, R2 is 47k Ohm, C1 is 0.47 uF.

I haven't taken the steps to calibrate it yet, just checked it out with the multimeter. The zero-rotation output is about 2.5 V, and roughly 90 deg/sec seems to have a 1 V drop.

I like Mark Ramsey's idea of using a turntable to calibrate the rate sensors. Next time I'm browsing for equipment to scavenge at a thrift store I'll pick one up.

The above schematic should be in a monospaced font, but it appears in Mozilla in a proportional typeface. See my post to the mailing list for a properly rendered version.

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