A comment from George Harris:

I am very convinced that a kit could be made to sell for less than $150,
but it depends on the volume.  My guess is that it would require a
market size of more than 1000.  If this is a realistic number, and I would
think it is, an organized project of the PSN should make it easy.

There are many possibilites, but based on my thinking over the past
few years with a similar objective in mind, the following are ideas:

The sensor is a simple vertical upright pendulum with one or two axes,
optical sensing, and magnetic coil feedback.  I believe I could make such a
unit to sell
for $75 or less in kit form including the components for the feedback
circuit.

Use an 8 bit A/D plus an amplifier with gain of 128 to provide at least
12 bits of output by combining the two words in a pic class microprocessor.
This type of processor can also provide a serial interface with proper
programming.  The component cost should be in the $40 range and
can be on the same board that has the optical sensors.

I would be glad to cooperate with anyone else to try the design.  My
major capability is in the mechanics and low cost design of the sensor.

George Harris





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