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Sudden APM.1 failure - help !

Started this discussion. Last reply by Simon Jan 23, 2012. 3 Replies

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Gyros for ArduPilot

Posted on January 15, 2009 at 6:53am 7 Comments

I understand the issues about using simple rate gyros with an autopilot - i.e. you can't unless teamed with accelerometers etc - but could one use a head-lock gyro for stabilisation via aileron control ?
Max flight time would be about 10 - 15 mins.


Comment Wall (3 comments)

At 11:58am on February 13, 2010, Mark Whitehorn said…
What kind of problems were you seeing related to use of a 4.7uF cap for C21? The datasheet calls for a low ESR 4.7uF. My Razor 9DOF seems to be working OK on the bench, but perhaps I don't know what problems to look for.
At 4:47pm on February 13, 2010, Simon said…
If it's working then you're fortunate ! With the HMC5843 board (same device/circuit) I found that the 10uF cap - as fitted by Sparkfun - did not allow any data to be collected. Nathan at SF said that this was known to be a recurrent problem but that they had had working units using either the 4.7 uF cap (as recommended by HP) or the 10 uF cap and were unable to replicate the problem.
If you look for info on the web about using the HMC5843 you will see that many other users have reported that these lower value caps just aren't suitable but that increasing it to e.g.100 uF gives a working result. Jordi has had the same problem and uses a 33uF cap in the DIYD mag board.
I was frankly surprised that SF chose to stick with the low value cap for the 9DOF board.
I wondered whether the cause of the problem might be the strength of the local field components but NW UK and Denver are pretty similar.
At 10:16am on February 14, 2010, Mark Whitehorn said…
Thanks for the info. After websurfing for a while, my guess is that the problems are due to high ESR (equivalent series resistance) which depends on both layout and capacitor type. I'd hope the engineers at Honeywell would specify a conservative datasheet value for the capacitance, and that only leaves ESR as a variable.

I'll post a comment if I run into any problems with my 9DOF board.

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