OBSERVATIONS FROM NORWAY. 1001101815Z.
A simple rotor controller.

This rotator controller uses an 16F877 PIC to drive an H-Bridge arrangement that controls the rotator motor for azimuth Rotation.  The PIC based system was described in an earlier OBS.  This add-on unit allows manual control of the rotator via an H-bridge arrangement and adds flexibility for the user.




Azimuth Rotator circuit and truth table.


The transistors used in the H-Bridge were from the junkbox. They are probably overkill for this application, but they were available at the time.



H-Bridge internal arrangement.


 H-Bridge (top) and PIC controller (lowerphoto)

 I can 'mechanically' control my homebrew rotor with a reversible connected double pole, double throw 6 point switch but I needed to be able to do it either mechanically 'or' automatically - so I came up with this little circuit. It's a transistor H-Bridge circuit controlled by either a single pole switch (mechanical) or 2 x grounded base PNP transistors. The H-Bridge consists of 4 x NPN transistors allowing a DC motor to turn in either direction - (left or right on my home brew system). For anyone contemplating something similar, the diagram is self explanatory - (the'truth' table is shown). Grounding one of the PNP bases will cause the motor to turn in one direction, grounding the other assures the rotor will turn in the other direction. grounding neither - or both and the rotor doesn't move.



73 John,
LA2QAA