Sajjad..

I have had a chance to fix one that was damaged, and I can attest that it is
quite simple, identical to the RC radio remote control concept.  The motor in
the LNB I worked on was in fact a model car type servo.  The wires are +v,
ground, and control.  Control is a PWM signal.  The signal goes through two
main positions to achieve 90 degrees, and skew shifts the PWM to trim the
degrees.  The control pin usually goes through an open collector and pullup to
survive surge (will you see much lightning in Pakastan?)  The one I fixed had a
7407 (??) open collector driver that was damaged.

Chris Eddy
Pioneer Microsystems, Inc.

sajjad.akhtar wrote:

>      Hi all,
>
>      Last weakened my bro showed me a little circuit that was to control
>      the polarize in the LNB and tuner in the dish receiving unit.
>
>      That was equipped with a microcontroler 8051. I am interested in
>      building my own. But i dont know how servo moter in polarizer is
>      controled and what sort of signal is used to control the tuner circut.
>      (Same tuner comes in many dishreciever circut like winer sat etc)
>      I was asuming that signal should be of analog but both the digitizer's
>      servo motor and tuner were directly controled from the microcontroler
>      output (no capacitors for pwm ... DAC) and that version of 8051 doesnt
>      contians any DAC.
>
>      This means they were using digital signal. Can any one help me that
>      what kind of signals both the units uses.
>
>      thanks
>
>      sajjad Akhter
>
>      sajjad.akhter@cressoft.com.pk