David P Harris wrote:

> I hadn't realized this is how they worked... very elegant.  So, if I 
> want to get to another position quickly, I could exaggerate the 
> position to maximize the error to increase the movement per pulse, and 
> then sent the correct position to zero in on it.  This would have to 
> take into account the characteristics of the servo, but could give 
> better performance.
> David
>
So, is this the simplest cicuit that would work?:

                                 V
                              +--+--+
                              |     |
                              R     R
                              |     |
                              +-Mot-+
                              C     C
           +-----one-shot----B       B----+
           |                  E     E     |
           |                  +--+--+     |
pulses-----+                     G        |
           |                              |
           +------------------------------+
where the duration of the one-shot is dependant on the servo position. 


If no pulse, both transistors are off, no movement.
If pulse = on-shot, both transistors on, no movement.
If pulse longer that one-shot, motor moves one way. 
If pulse is shorter than oneshot, motor moves the other way. 

It is wasteful as if both transistors are on they just sink current 
without any work being done. 

David

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist