I have some friends' graduation report (A sun tracker, used with a solar cell, ... only a hardcopy)
major observations:
* Continuous tracking not necessary (very small gain in power), they put the 16c71 to sleep and woke it up every 30minutes (using a 555, AFAIR)
* They used a PIC (an improvemnt over an older PC-Based project)

Here's a few ASCII Drawings

+--------------+
|*1ssssssssss2*|
|  ssssssssss  |
|  ssssssssss  |
|  ssssssssss  |
|*3ssssssssss4*|
+--------------+

s=solar cell
*=sensor

sensor  amp   +---+
*-------|>----| 1 |    +------+
*-------|>----| 6 |----+Motor |----MOTOR#1
*-------|>----| c |    |      |
*-------|>----| 7 |----+Driver|----MOTOR#2
              | 1 |    +------+
              +---+

They used a simple algorithm:
ON WAKE UP:
turned power on for everything
if Sensor1+Sensor2>Sensor3+Sensor4 then move up else move down
if Sensor1+Sensor3>Sensor2+Sensor4 then move left else move right
repeat until Differences very small (optimal position)
turned power off from most of the board
SLEEP for 30 minutes

At 02:12 25/12/98 , you wrote:
>Hi All,
>
>I am trying to design a project to track the sun.Ê Has anyone ever tried to
>do this.Ê Any help would be greatful.
>
>Brian
>

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