I read that you should not connect your servo's positive and negative wires to the apm output. I have 5A BEC which I would like to power the apm from, but can I also connect the servo up to this? In terms of the 5A limit this shouldn't be a problem because my Servo will never draw more than a couple of amps and the APM will use the same, my only concern is if the current spikes to the servo will affect the apm.Thanks!
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I believe the issue is, as you say, current spikes caused by momentary voltage drops, and also noise produced by the servo conducted into the APM board's circuitry.
But in this YouTube video, at around the 0:50 mark, he implies you can hook up the servo of a Tri-copter to the ArduPilot board.
I would think Bruce Simpson (that New Zealander doing RCModelReview) would have material on this. He seems to be a hardcore electronics guy.
Tom Mahood > Hugh HemingtonJune 17, 2014 at 7:18am
I think you are reading a bit too much into what he says. He merely says the output rail is where you connect the ESCs or servos, which is exactly correct. But also note he speaks in greater length about the JP1 jumper and cautions about when to connect it. Overall his video was pretty good, but he spoke in generalities about hooking up multicopters. Tricopters are a little different due to their servo powering requirements and that they also represent a rather small minority of APM useage.
So would you recommend getting another bec or ESCs with BECs built in?
Tom Mahood > Niall WoodwardJune 15, 2014 at 8:42am
Best course of action for powering the APM is via a Power Module. If you can't do that, use a separate, high quality BEC plugged into the APM's input rail, keeping the JP1 jumper removed.
Your concern is a valid one, which is why it is a bad idea and why what you read recommends against it. Current capacity isn't the issue. Voltage spikes are.
Replies
I believe the issue is, as you say, current spikes caused by momentary voltage drops, and also noise produced by the servo conducted into the APM board's circuitry.
But in this YouTube video, at around the 0:50 mark, he implies you can hook up the servo of a Tri-copter to the ArduPilot board.
https://www.youtube.com/watch?v=TFCmUuvcH04
I would think Bruce Simpson (that New Zealander doing RCModelReview) would have material on this. He seems to be a hardcore electronics guy.
I think you are reading a bit too much into what he says. He merely says the output rail is where you connect the ESCs or servos, which is exactly correct. But also note he speaks in greater length about the JP1 jumper and cautions about when to connect it. Overall his video was pretty good, but he spoke in generalities about hooking up multicopters. Tricopters are a little different due to their servo powering requirements and that they also represent a rather small minority of APM useage.
Best course of action for powering the APM is via a Power Module. If you can't do that, use a separate, high quality BEC plugged into the APM's input rail, keeping the JP1 jumper removed.
Okay will do, thanks for your help :)
Your concern is a valid one, which is why it is a bad idea and why what you read recommends against it. Current capacity isn't the issue. Voltage spikes are.