Hello everyone!
This is probably a stupid question, but I am still confused regarding the Pixhawk servo rail. The ardupilot website claims that the Pixhawk does not supply power to the servo rail. But so far the only thing plugged into my Pixhawk's servo rails are the servos themselves, and they seem to be getting power just fine (I even flew the plane a couple of times). Why does everyone say I need to supply a separate power supply to the servo rail when my plane seems to fly perfectly fine without one? I am still confused, and I was hoping someone could please explain it to me.
Regards,
-Andrew
Replies
@Andrew,
Do you have an ESC (Electronic Speed Control) plugged into the servo output bus?
If so, does it have a BEC in it that is most likely supplying +5vdc to the servo output bus power rail
The BEC in the ESC is therefore powering the servos.
The Pixhawk will use the BEC +5vdc not only to provide power to the servos, but will use it as a secondary source to back up the Power Module.
The BEC output should not be greater than +5.5vdc.
It is also recommended to add a 5.6vdc 5 watt zener Link across the servo output power bus rail between the (+) and (-) terminals to clip any servo motor induced voltage spikes above +5.5vdc that can cause a Pixhawk to reset.
Regards,
TCIII AVD
he did wrote "But so far the only thing plugged into my Pixhawk's servo rails are the servos" - so it's very strange.
@Andre,
He says above: "Why does everyone say I need to supply a separate power supply to the servo rail when my plane seems to fly perfectly fine without one?"
I do not know how he can get his plane into the air without an ESC to power the plane's motor from the plane's battery so he must have an ESC/BEC attached to the servo output throttle channel of the Pixhawk.
Regards,
TCIII AVD
Based on the information, (nothing else than servos) - I guess it may be a bad clone - it's hard to even call it a clone, maybe bad imitatio would be more likely.
OpenPilot community discovered recently garbage like this: https://forums.openpilot.org/topic/57613-so-you-bought-the-clone-fl...
I've seen myself low voltage switch mode power supply clones assembled with random capacitors of similar physical size (higher voltage, lower capacitance), instead of the correct capacitors.
So when it comes to lookalike-garbage in the world of electronics, even components are cheap, nothing surprises me. :)
Andrew A - where did you buy the Pixhawk, - and - if you vought it anywhere else than 3DR , and you did not use ESC or BEC, - could you please open it and post close up photos of the electronics inside ?- I could quickly compare it to the original schematics.
Dear all,
Thanks for the responses! Sorry for the confusion and the late response, but I have attached a picture of what I am talking about. As you can see, I have only 5 (five) different connectors plugged into the servo rail. They are:
1) Futaba receiver
2) Ailerons
3) Rudder
4) Elevator
5) Throttle
Nothing else is plugged in (i.e. "no power"). However, all of these things work and I have flown my plane as is with no problems. I am not sure if I am understanding what is really going on...Can someone please explain why I am able to still fly my plane as is without plugging in a separate BEC directly to the servo rail and without including a Zener Diode?
Pixhawk in Bormatec.JPG
You say Bormatec : which make mostly small electric planes, in you Throttle control an actual servo servo (for a gas/nitro engine) - or is that an ESC for electric motor ?
If you have an ESC - then it's most likely to have an "BEC" in it, to verify ,disconnect 5 and servos should not work.
Hey there!
Just wanted to let you know that you were correct. I disconnected the ESC/Throttle connection on the servo rail and I had no power.
Mystery solved! Thanks for your help!
And no, this is not a knock-off or a fake Pixhawk.