Polarotor Servo Controller
Latest:
2010-02-23: Check out Budfoot's more robust version.
About:
This is a device that sits between your large C-band satellite dish (BUD) and your FTA receiver. Old satellite dishes have LNBFs that use a servo to control the received polarity. Newer FTA receivers expect an LNB that has voltage controlled polarity (18V/13V). If you have this problem, this device makes your life much easier.
Notes:
The controller is built around the Arduino AVR board; specifically the RBBB Freeduino Board from Modern Devices. It's very simple.
The original design only used one potentiometer to set the center between vertical (V) and horizontal (H). Using an offset, it worked ok, but I found that from servo to servo the offsets changed. I think this is due to the age of servos. No two servos that I tested agreed on what pulse width would be 90 degrees from another reference. So... now the design uses two potentiometers, one for each polarity.
If you want to lose the potentiometers all-together, you can, just hook one up temporarily and use the serial out arduino command to find out what servo settings each polarity should be set to, and then hard code those values into the source-code and re-burn. This might be good for outdoor installations. It's how I'm running things at the moment.
If you're going to have the box indoors, you might as well use both potentiometers so you can fine-tune things for any odd-skewed-satellites. Knobs! Throw an ammeter on there for visual feedback and you'll be rollin' in style.
You need to use an LM7805 regulator with the RBBB; not the voltage regulator that comes with the kit. The RBBB's PCB board is designed to accept the 7805, so this is no big deal. If you don't use a 7805, you will be sad.
Questions? Please feel free to ask me at www.satelliteguys.us. Username equant.
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