s-band
Specialist Contributor
- Joined
- Feb 7, 2016
- Messages
- 1,189
- Reaction score
- 1,846
- Points
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- My Satellite Setup
-
1.5m IRTE PF, Octagon OSLO external Ref., TBS6983,
Various L, S, C, X & Ka bits. 1.2m S/X/Ku/Ka Prodelin on Az-El (being refurbished)
- My Location
- Essex
I wanted a quick. simple, servo driver. I bought one of the cheap RC servo testers but that only output 1.00-2.00ms pulse widths. The Chaparral corotor that I have needs 0.3-2.5ms to cover the full 180 degree range. Having seen dx qwer’s controller here
the Pololu Maestro looked good. It is available from:
Pololu - Micro Maestro 6-Channel USB Servo Controller (Assembled) or Micro Maestro 6-Channel USB Servo Controller (Assembled) | 1350 | Pololu
Pololu recommend (and wire the board for) use of an external supply for the servos. However, the Corotor only draws about 500mA starting and 100mA running current with minimal draw when idle. Below are pics of how to wire the USB 5V to the servo supply. I’ve added a 330u capacitor to even out the peak current. This way I’ve got a USB to servo adapter without the need for yet another PSU.
It should be possible to run a few servos from the USB line as long as you only operate one at a time. A caution is that the min and max pulse widths must be set such that the servo is not held against its end stop. If that happens the current will be high and the servo may cook. It is a good idea to measure the servo current and set the limits whilst running it from another PSU to make sure that the current is at a safe level (<=500mA peak) before connecting it to the USB.
Controlling the servo can be done by using the slider or by inputting a pulse width directly. The latter could be used to set pre-calculated polarisations. If anyone is into software it would be possible to use the Pololu input functions to measure the LNB voltage and switch polarisation accordingly.
Code:
https://youtu.be/v4_RKO18yuEPololu - Micro Maestro 6-Channel USB Servo Controller (Assembled) or Micro Maestro 6-Channel USB Servo Controller (Assembled) | 1350 | Pololu
Pololu recommend (and wire the board for) use of an external supply for the servos. However, the Corotor only draws about 500mA starting and 100mA running current with minimal draw when idle. Below are pics of how to wire the USB 5V to the servo supply. I’ve added a 330u capacitor to even out the peak current. This way I’ve got a USB to servo adapter without the need for yet another PSU.
It should be possible to run a few servos from the USB line as long as you only operate one at a time. A caution is that the min and max pulse widths must be set such that the servo is not held against its end stop. If that happens the current will be high and the servo may cook. It is a good idea to measure the servo current and set the limits whilst running it from another PSU to make sure that the current is at a safe level (<=500mA peak) before connecting it to the USB.
Controlling the servo can be done by using the slider or by inputting a pulse width directly. The latter could be used to set pre-calculated polarisations. If anyone is into software it would be possible to use the Pololu input functions to measure the LNB voltage and switch polarisation accordingly.
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