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Re: [Paparazzi-devel] Re: 5v onboard regulator

From: Nicholas Wagner
Subject: Re: [Paparazzi-devel] Re: 5v onboard regulator
Date: Mon, 17 Aug 2009 15:15:03 -0600

All -

The use of optocouplers would be a great addition to the servo board,
however due to time constraints and other constraints of our project,
rev1 of this board is to be delivered later this week.

To briefly describe our project, we are working on the design of a
fuel cell powered long endurance UAV. and Two challenges that come
from this are weight and electrical efficiency (this may be an
oversimplification).  Original specifications of the fuel cell
specified a Vin max of approximately 70VDC which made our electrical
design process a little interesting.  The latest specification dropped
this down to 40V which is much more feasible.

At this time, the board we are designing in house uses two switching
regulators, LM5088 to provide high current output at 5V and 12V for
use by our electronics and other peripherals.  These two regulator
circuits have been designed to limit EMI.  It uses a high current 5V
linear regulator and a diode drop (to 12V) for a 3C lipo battery
backup.  This board, due to the constraints of our funding source will
not be Open source/GPL.  However, I can personally design another
version of this board for the Paparazzi community, if there is enough
interest, that will be Open Source/GPL as an act of good will :).
There is one drawback.  I personally am a Mechanical Engineer, so
there are many more, better qualified, people to do this.

Once I have some time to put this together, I could make a preliminary
design in eagle for the schematic and then open a 'design space' on
the wiki for other contributors.


On Mon, Aug 17, 2009 at 2:28 PM, Rui Costa<address@hidden> wrote:
> Hello,
> That board is opensource? Can we know more about it?
> Regards
> Rui Costa
> On Mon, Aug 17, 2009 at 7:43 PM, Christophe De Wagter <address@hidden>
> wrote:
>> If I remember well, the 5V switching regulator was introduced in the Tiny
>> 0.9 boards to reduce the heat of the linear BEC regulators often found in
>> small motor controllers because servos often use more power in automatic
>> flight flight than in manual flight.
>> Nowadays several good motor controllers have beter power regulators than
>> the tiny TINY board, especially in "not so tiny" aircraft. That is why we
>> made a tiny board with only the 3.3V regulator. Servos (and the 6V
>> compatible decade counter) are powered by the 6V motor controller BEC (in
>> our case a 5LiPo 120Amp brushless controller with a 8Amp switching BEC). The
>> 3.3V regulator is changed to a low dropout lt1963 that accepts much more
>> than 6V and still works with 3.6V (unlike the 3940 on the tiny2.11!!). The
>> board also has a serial optocoupler port to allow the RC and ADC to be
>> located further away in case of
>> problems.
>> Christophe
>>> ---------- Forwarded message ----------
>>> From: antoine drouin <address@hidden>
>>> In a larger aircraft, servos are likely to be far apart from the
>>> autopilot. Why don't you guys use an external servo driver located
>>> close to clusters of servos and containing the adequate power supply.
>>> I made such a board some time ago for a specific application
>>> ( . It connect to the autopilot
>>> through CAN bus wich is more robust than PPM on longer wires.
>>> Regards
>>> Poine
>>> ---------- Forwarded message ----------
>>> From: "Prof. Dr.-Ing. Heinrich Warmers" <address@hidden>
>>> for high power system it would be nice to have no dc current  ways from
>>> the autopilot to the drive and servo system.
>>> A good way to eliminate EMC problems will be the use of opto couplers
>>> also for the servo counter.
>>> One for count and one for reset.
>>> Another free GPL autopilot project have also isolated the Servo systems
>>> with opto couplers to.
>>> Another good idea is to isolate the RC Receiver by a opto coupler to.
>>> Heinirch
>> _______________________________________________
>> Paparazzi-devel mailing list
>> address@hidden
> --
> Rui Costa
> _______________________________________________
> Paparazzi-devel mailing list
> address@hidden

Nick Wagner
Mechanical Engineering
Colorado State University
C: 970.631.2989
E: address@hidden

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