Extended Servo Range
Last updated
Last updated
A servo is controlled by a PWM signal, which is a pulse that varies from 1ms to 2ms. Your average servo will rotate 90 degrees over this pulse range.
The Head Tracker can only output a maximum range of 988us to 2012us. This is the slightly over the limit of a standard PPM trainer signal.
The values in your radio are also limited in range to similar values. All the way over the air and to the receiver. Some receivers have an extended range option which can buy you a little extra range but not usually enough.
Since you want to control a camera with a pan of likely more than 90 degrees and we are limited on the signal all the way up to the receiver you have a few options.
Servo extender. These devices take the incoming 1-2ms pulse and change the range of the output to 500us to 2500us, which for many servos will cause them to overtravel up to 180degrees. Not all servos will work with this method. Check amazon, ebay or your favorite hobby supplier.
Flight controller If you are using a flight controller you might be in luck and be able to set the range of output to 500us - 2500us in the software, which will work just like #2.
A lot of the cheapo servos will be very grainy and unsmooth motion especially once they have their range extended. Purchase a good quality one for pan.
Buy a 180+ degree servo Purchasing a servo that was designed for 180+ degrees of motion is one of the best options. Such as Note: If your buying a servo that says it will do 180deg, be sure to read the fine print. Sometimes a servo will say 180deg but the signal needed to get it there is 500us-2500us. Which is really just a normal 90 degree servo, and brings us to #2
Resistor Mod Since a servo is a closed loop device that holds its position based on feedback from a potentiometer if you add two resistors to that potentiometer it will travel further. Experimentation on the correct values might be needed.
