In a message dated 31/08/02, gjharris@............. writes:

> 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 
> 

       If you use a 'cottage industry' rather than the 'big corporation' 
approch you should get it lower.  

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 
> 

       It would be a great opportunity to use the four pole ex hard drive 
magnets and thin flat coils to make and integrating SG seis. Sensing could be 
either linear optical or linear magnetic displacement.

I u
> se 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.

       The 10-bit Dataq unit for $25, DI-194RS, looks like a good starting 
point, with a four channel 240 sps capability.    

       Regards, 

       Chris Chapman
In a message dated 31/08/02, gjharris@............. writes:



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 you use a 'cottage industry' rather than the 'big corporation' approch you should get it lower.  



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.



       It would be a great opportunity to use the four pole ex hard drive magnets and thin flat coils to make and integrating SG seis. Sensing could be either linear optical or linear magnetic displacement.



I u

se 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.




       The 10-bit Dataq unit for $25, DI-194RS, looks like a good starting point, with a four channel 240 sps capability.    



       Regards, 



       Chris Chapman