[Gasification] Gasification Digest, Vol 17, Issue 8

[David G. LeVine]

At 10:08 AM 11/13/2007, you wrote:
>Targeting 80 millivolts with manual controls distracts the driver 
>from the task at hand. If an air-valve could be positioned by logic, 
>a biomass-fueled vehicle could be operated much more safely.

The logic is not difficult.  Do you want a servo motor driver or a 
stepper driver?  How big a motor?

The best way is a buffer amplifier, an integrator (yes, those are 
necessary to smooth things out) and a micro (like a PIC16F family 
with an A/D built in) to make decisions.  You are talking no more 
than $100.00 for the logic, but finding a coder may be rough.  For a 
stepper, the controller can be as simple as 4 resistors, 4 FETs or 
BPTs and 8 diodes.  For a DC motor, it isn't much worse.

Remember, you are looking for a fairly coarse and slow (for a micro) 
system.  A time constant of 1 second is incredibly fast for a human 
and slow for a micro with a simple program.


David G. LeVine
Nashua, NH  03060