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DeveloperPermalink Reply by R_Lefebvre on July 13, 2012 at 1:42pm

I have run 4 digital servos on Outputs 1-4 with my heli, but it's becoming not recommended.

I would recommend building a little servo breakout board.  Bring the PWM to the signal pin, and then power and ground for the servos that doesn't go through APM.  The ground must be tied to the APM ground, however, in star formation.

Here's a picture of one that I made, which includes a 2803 chip for the LED's, you don't need to worry about that:

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Permalink Reply by Rick Stewart on July 13, 2012 at 1:48pm

I have used digital servos connected to the apm2 via the camera gimbal tilt, and roll connections.  They work quite well, you hear them fidget allot but that is the constant updating from the APM2.  Unfortunately I cannot comment on anything else other then they work.  One is a micro servo, and the other is a standard size.  I use a separate battery for my APM so I don't know the effects of flight time.  One thing you might consider is using a larger battery with a lower C raiting.  I say this because its my understanding that the APM uses 200mah when in operation.  Add some sensors, some telemetry and some hungry digital servos and you could be around 300 - 350.  That doesn't leave allot of wiggle room for having a battery that is not fully charged / old / etc.  Just a thought.   My previous APM2 battery was a 780 4S but I decided to save 20 grams and use a larger capacity (1200 mAh) battery with a lower voltage ( 14.8v vs 7.4v).  I hope this helps, if you have any more questions just ask.  Cheers,

Rick

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Permalink Reply by Brian McGrath on July 14, 2012 at 6:20am

Thanks, guys! I appreciate the feedback. I've also received suggestions that I should be using a 3300uF electrolytic capacitor in the power supply to the servos to prevent sag when there is high demend. Have you tried this? Do you suggest using two BECs?

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Permalink Reply by Milz on July 15, 2012 at 3:21pm

Hello

Why not use the BEC from the ESC ?

I had a brown out inflight with two servos for my gimbal connected.

So i connected the servo power to two of the 5V outs of the ESC

and the Signal line to the APM2.

Im a noob so is this no good idea ?

mfg milz

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DeveloperPermalink Reply by R_Lefebvre on July 20, 2012 at 7:13am

That's not a bad idea.  Use the BEC from one ESC to power the APM, and the BEC from a second ESC to power the servos, keeping them segregated.  It will probably work, and it's a really good idea to keep servo loads off the APM power supply.

Brian:

I've gone as far as to use a massive capacitor bank in the mF range.  But ideally, I think servos should always be completely segregated from the APM in any case.  Because if one stalls out, it'll still drain that cap, and then take down the APM power supply.  It happens.

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