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Old Sep 27, 2012, 01:24 PM
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Pulse witdth=1-2 ms with 20ms cycle =50hz........400hz =2.5ms.... but it needs to keep standard pulse width max 2ms ....so only 0.5ms between pulses.
Vey nice explanation here.
http://wiki.openpilot.org/display/Doc/TurboPWM
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Old Sep 27, 2012, 01:25 PM
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can't believe someone actually build and fly this little guy. thanks for thread.
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Old Sep 27, 2012, 01:47 PM
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can't believe someone actually build and fly this little guy. thanks for thread.
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Originally Posted by bigtruck169
by any chance they made a board for spektrum radio? urs look promising, with $18, really can't beat that.
hope you dont mind a reply here because i have pm overflow problems.

the horizon mqx contol board is dsm compatible but costs around $36 which is more than enough to buy a couple v939 boards and a compatible radio and have money left over. however if you want to do that this thread shows how to put an mqx board in a ladybird frame:

http://www.rcgroups.com/forums/showthread.php?t=1647401

i think you can save a lot of money by using that board in a diy frame like mine and end up spektrum compatible.
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Old Sep 27, 2012, 01:47 PM
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Noob question - motor amp draw must be less than what the ESC can put out, right?

OK so this motor: http://www.hobbyking.com/hobbyking/s...er_7700kv.html

This ESC:

http://www.hobbyking.com/hobbyking/s..._ESC_3_5A.html

But which prop? GWS 5030 is only comes as one direction.
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Old Sep 27, 2012, 01:52 PM
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Originally Posted by midelic View Post
Pulse witdth=1-2 ms with 20ms cycle =50hz........400hz =2.5ms.... but it needs to keep standard pulse width max 2ms ....so only 0.5ms between pulses.
yes, you are right. the 400hz jesolins mentions are only available with special high speed i2c and spi protocols. not possible with servo pwm. i think 4ms/250hz is the fastest for most servos and escs. even then it causes trouble with some and i vaguely recall having to drop down to 8ms/125hz for compatibility reasons.
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Old Sep 27, 2012, 02:00 PM
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Dave,
Yes I am speaking of PWM update rates form the FCB to the ESC which then has to properly handle that rate, so 400hz or 2.5Ķs. From my large multicopter experience multicopters just start flying OK at about 200hz update rates in no wind conditions. However there is definitely a positive improvement in flight performance stability in wind of 10-15kts with update rates closer to 400hz or above. Examples of multicopters that are top of the line in stability and performance that use even higher ESC update rates are the Mikrokopter and the Astec multicopters. The MK uses 500hz I2c ESC update rate. The Astec designs use I2c ESC update rates of 1khz. They are the ones you see in the now famous University lab videos.

The standard PWM ESC CopterControl, Mutiwiicopter, Kapteinkuk, Autoquad AQ6, and UAVX32 all use 400hz PWM update rates or higher, which is also configurable in some of their setups, for the best stability performance in wind too. The Simonk ESC firmware makes this possible in off-the-shelf ESCs as well as making them multicopter friendly by turning off LVC and making the throttle linear with no smoothing, etc. The Bill Nesbit AutoQuad ESC32s that are designed specifically for standard PWM multicopter use start at 400hz update rates.

I know...in my mind the physics of it is like measuring with a micrometer(gyros and accelerometers) and marking with a grease pencil(FCBs) than cutting with an axe(ESCs/motors/props) ..but operationally does increase multicopter flight performance.

ESC update frequency thread

Cheers,
Jim
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Originally Posted by dave1993 View Post
...
if you mean frame rate iirc its 4ms (250hz). from my experience with full size multicopters there is little practical difference between 200hz and 400hz anyway. even the 50hz of standard rc radios performs ok in most cases. many will dispute this. few unmodified esc and servos work at those speeds and they are its intended use so no extreme rates here. its designed to work with off-the-shelf components but of course will work with those hotrod flashed escs too.
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Originally Posted by dave1993 View Post
yes, you are right. the 400hz jesolins mentions are only available with special high speed i2c and spi protocols. not possible with servo pwm. i think 4ms/250hz is the fastest for most servos and escs. even then it causes trouble with some and i vaguely recall having to drop down to 8ms/125hz for compatibility reasons.
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Old Sep 27, 2012, 02:03 PM
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Originally Posted by installerblizz View Post
Noob question - motor amp draw must be less than what the ESC can put out, right?

OK so this motor: http://www.hobbyking.com/hobbyking/s...er_7700kv.html

This ESC:

http://www.hobbyking.com/hobbyking/s..._ESC_3_5A.html

But which prop? GWS 5030 is only comes as one direction.
this cw/'ccw thing is a problem. in any case im sure a gws 5030 will burn up that motor and the esc too. even 3" is pushing it imo. also dont forget that bigger props will draw HUGE current and youll need a really big battery. i think the props we use here are best choice for that motor. the 1mm hubs fit that 1mm shaft perfectly. and they are available cw/ccw and cost 20 cents instead of a buck.
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Old Sep 27, 2012, 02:09 PM
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Originally Posted by dave1993 View Post
this cw/'ccw thing is a problem. in any case im sure a gws 5030 will burn up that motor and the esc too. even 3" is pushing it imo. also dont forget that bigger props will draw HUGE current and youll need a really big battery. i think the props we use here are best choice for that motor. the 1mm hubs fit that 1mm shaft perfectly. and they are available cw/ccw and cost 20 cents instead of a buck.
Ah crap I meant 3020. That's what is recommended according to HK. It also says 36g thrust. How much less would we get with the ladybird props?
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Old Sep 27, 2012, 02:20 PM
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first of all i think you have to stop believing these chinese ad specs. iirc the best you can do reliably with that combo is 24g. and mine got REALLY hot even at that point. i havent actually tried these props on those yet so not sure but im guessing 15-20 grams? its really not how much thrust you can get but how much you can get reliably for reasonable duration w/o cooking the windings. since i am going to dig out the bl motors and escs to check that converter i might as will hook up the test stand too. ill try to anyway.
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Old Sep 27, 2012, 02:23 PM
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Maybe this 5g inrunner (1mm Shaft) for $5.99 (free shipping) could be interesting for the brushless project :
http://www.aliexpress.com/item/Free-...581262389.html
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Old Sep 27, 2012, 02:28 PM
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Originally Posted by jesolins View Post
Dave,
Yes I am speaking of PWM update rates form the FCB to the ESC which then has to properly handle that rate, so 400hz or 2.5Ķs.
its been couple years since i played with the big ones so maybe they have decided to 400hz pwm is ok after all. i thought back then most reflash was for i2c or spi. i know my kk controllers do not produce anything close to those rates. no matter what these are not an optrion here where we want to use off the shelf components like the hk 1g esc. and you can always use a high rate esc with low rate fc but not the other way around.

since ive actually spent very little time flying these i will definitely assume you know what your talking about regarding wind etc.. for me staying up for 60 seconds w/o smashing the fame to pieces was a major accomplishment.
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Old Sep 27, 2012, 02:34 PM
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i haven't read through the whole thread. by any chance u find any board that can use spektrum radio? thanks for the least expensive toy. mike
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Old Sep 27, 2012, 02:37 PM
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Originally Posted by bigtruck169 View Post
i haven't read through the whole thread. by any chance u find any board that can use spektrum radio? thanks for the least expensive toy. mike
hope you dont mind a reply here because i have pm overflow problems.

the horizon mqx contol board is dsm compatible but costs around $36 which is more than enough to buy a couple v939 boards and a compatible radio and have money left over. however if you want to do that this thread shows how to put an mqx board in a ladybird frame:

http://www.rcgroups.com/forums/showthread.php?t=1647401

i think you can save a lot of money by using that board in a diy frame like mine and end up spektrum compatible
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Old Sep 27, 2012, 02:44 PM
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Dave,
Yes and if the HK 1g ESCs use an ATMEL processor and we can get to the pins, we might be able to interest Simonk in assisting us with proper multicopter firmware

Probably a bit off-topic in this great $18 scratch build quad thread, but here is a good example of what high PWM udate FCB/ESC rates and a well designed and coded multicopter can do today..in case you might have missed it
Autoquad v6.6r19 Position Hold in gusty and turbulent breeze. (2 min 45 sec)


Cheers,
Jim
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Quote:
Originally Posted by dave1993 View Post
its been couple years since i played with the big ones so maybe they have decided to 400hz pwm is ok after all. i thought back then most reflash was for i2c or spi. i know my kk controllers do not produce anything close to those rates. no matter what these are not an optrion here where we want to use off the shelf components like the hk 1g esc. and you can always use a high rate esc with low rate fc but not the other way around.

since ive actually spent very little time flying these i will definitely assume you know what your talking about regarding wind etc.. for me staying up for 60 seconds w/o smashing the fame to pieces was a major accomplishment.
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Old Sep 27, 2012, 02:45 PM
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Originally Posted by mystman View Post
Maybe this 5g inrunner (1mm Shaft) for $5.99 (free shipping) could be interesting for the brushless project :
http://www.aliexpress.com/item/Free-...581262389.html
that is a pretty good deal. i hate to think what i paid for my 1st hk 5g motor. and only $4.79 for ten. and that 1mm shaft is very attractive. hmmmm...
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