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Old 02-09-2011, 12:15 AM   #21
sidneyw
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MKS seems to be one of the best coming from Taiwan. Be interested to find out how long it will hold in e-stab. They provide frequency response spec in all servos listed.
http://mksservo.digart039.com/photoindex.php?cid=30
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Old 02-09-2011, 08:15 AM   #22
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Yeah, they have nice specs (and detailed as well), but I'm kind of leery of spending more $$ trying more out. A DS480 I bought seemed quick enough to match the specs, but had a troubling 'slow down' effect approaching a stop point. I'd like it to act like all the other tail servos I've experienced going full speed into the stop point and not visibly slowing to a stop. Seemed kind of odd
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Old 02-09-2011, 10:22 AM   #23
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Voltage drop from power hungry digital servos? Some standard digital servo could require 5 amp at full speed/stop/go; 5x4 will mean 20a+ bec, a huge different from analog servos when 7-10a bec was an overkill of yesteryear.

Interesting exchange at BeastX forum -
http://www.beastx.com/showthread.php...-on-Fbl-beastx

So, the guy lower "hurtz" on his HV, Highend servos.
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Old 02-09-2011, 11:49 AM   #24
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Doubt it, it is a micro servo. I read a similar effect reported on the next slower version of that servo line as well. Maybe the mini and full size MKS servos are better...but the micros are somewhat questionable
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Old 02-09-2011, 11:52 AM   #25
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Quote:
Originally Posted by sidneyw View Post
So, the guy lower "hurtz" on his HV, Highend servos.
Maybe it really hurtz the wallet blowing up $$ servos left and right .
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Old 02-09-2011, 12:11 PM   #26
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As long as the servo is not hot after flight the hz should be fine right? I only need to lower frequency if the servo gets really hot right? At least thats what I understand.. Can a servo fail from to high of frequency even if its not getting hot? I want to be sure as Im installing a microbeast on my 700E as we speak and I am going to run the servos at 7.5v and 200hz. using the align 610's. I ran them all last season at 8.4V with the 3G no problems..
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Old 02-09-2011, 12:28 PM   #27
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Generally, faster switching results in more heat. If the servos dont get hotter running them faster, I would assume that the circuitry is able to handle the increased frequency. I'm going to do some testing with my Beast setup at various frequencies with an IR thermometer to see how faster refreshes work out.

Now on an over-voltage situation, all bets are off, as the circuitry might be designed to handle x amount of voltage (electrical 'pressure'), and running it at a higher voltage may result in a sudden failure with no warning. (Think of a hose bursting with too much pressure in it). Compound the higher voltage and higher freqencies...things could get interesting.

I'd be kind of curious....anyone have a spec for what the Mikado 'digital' refresh rate is?
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Old 02-10-2011, 01:18 PM   #28
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I should have raised this question from the beginning -

The frequency of servo is dictated by the servo circuit board sending signal to servo motor. The selection of frequency response at BeastX controller, I presume is to limit or setup signal time from the controller to servo. If a servo operates at 270hz it continues to do so despite the servo circuit receives update from the controller of less than 270hz.

Could servo failure has more to do with the servo in question?
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Old 02-10-2011, 02:54 PM   #29
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Quote:
Originally Posted by sidneyw View Post
I should have raised this question from the beginning -

The frequency of servo is dictated by the servo circuit board sending signal to servo motor. The selection of frequency response at BeastX controller, I presume is to limit or setup signal time from the controller to servo. If a servo operates at 270hz it continues to do so despite the servo circuit receives update from the controller of less than 270hz.

Could servo failure has more to do with the servo in question?
Yes the servo failure has to do with the servo itself. From what I know the higher the frequency the more often the servo gets a signal to do something. This means that in between the motor is 'resting'.... so the more signals it gets the less time the motor is resting therefore making more power, speed and more heat. Its the heat though that kills the servo.

So really the combination of frequency, voltage and load on the servo is what determines if the servo heats up and fails. This is why you need to see in flight how hot things get... if they get too hot then you need to do something like lower the frequency setting.
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Old 02-10-2011, 03:43 PM   #30
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Yes the servo failure has to do with the servo itself. From what I know the higher the frequency the more often the servo gets a signal to do something. This means that in between the motor is 'resting'.... so the more signals it gets the less time the motor is resting therefore making more power, speed and more heat. Its the heat though that kills the servo.

So really the combination of frequency, voltage and load on the servo is what determines if the servo heats up and fails. This is why you need to see in flight how hot things get... if they get too hot then you need to do something like lower the frequency setting.
You missed the point I was trying to state.
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Old 02-10-2011, 05:39 PM   #31
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Quote:
Originally Posted by sidneyw View Post
If a servo operates at 270hz it continues to do so despite the servo circuit receives update from the controller of less than 270hz.
I am not that knowledgeable here, but I'm not entirely convinced that this is the case. Others I'm sure will be able to contribute more, but my understanding was that a servo does little in its own right, in that it is rather passive. If it doesn't receive a frame, it has no information to process, and no instruction to send to the motor, so it doesn't send anything. To the best of my knowledge it will NOT invent one, at the previous last known good value, continuing on that basis, until it does receive another one, it simply forgets and does nothing. If this is the case then the rate set in the MB, is the rate that ends up at the servo, and ultimately at the motor, and is therfore directly responsible for driving it more often, and thereby increasing this rate increases the liklihood of overheating, within the tolerances of your servo of course.

Or maybe to put it another way, a servo capable of 200 Hz, given a signal of 65 Hz from the MB, will not be instructing its motor to take position at 200 Hz, but rather only at the received rate of 65 Hz.



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Old 02-10-2011, 06:32 PM   #32
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Quote:
Originally Posted by sutty View Post

Or maybe to put it another way, a servo capable of 200 Hz, given a signal of 65 Hz from the MB, will not be instructing its motor to take position at 200 Hz, but rather only at the received rate of 65 Hz.



Cheers

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Follow what you said ..... is my question.

I believe the servo is still running at designed spec in updating the motor at 200hz or every 5ms while the MB controller is sending 65hz or 15.38ms.
Now if the servo is capable of 120hz or 8.3ms, and MB is set to 200hz or 5ms. The servo can't update the motor at more than the speed it is capable of, and will still be updating the motor at 8.3ms.


True or False, is what I like to know. Or my thinking of how it works is totally wrong.
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Old 02-10-2011, 07:25 PM   #33
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I thought your question was the other way around, but no matter I see what you are saying now. In truth I don't know the answer. I am going off information that I have seen or heard from others, and not from first hand knowledge, but it was always my understanding that if you overdrive them it can indeed, somehow, make it through to the motor, and cause the motor to overheat and burn out. How true this is I cannot say, it hasn't happened to me, but it could be possible that the circuit is capable of passing frames at much higher rates, and that the manufacturer rates them down based purely on the ability of the servo to 'manage', for want of a better word, the additional heat that will be generated. Perhaps under little to no load, they can all run at 333 Hz, I can't say. Certainly 333 Hz still 'fits', again for want of a better word, when considering the maximum pulse width of around 2ms, and if the circuit can reset and be ready again in time, then it would pass it, as the pulse itself would just look the same.

What I think we do know is that FBL loadings are higher, so if anything will find out if you are driving your servo beyond its limits, it will more likely be in an FBL set-up than with the more traditional FB.

Hopefully an expert can chime in, and let us know a little more clearly what goes on. I for one would be interested to find out more.

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Old 02-10-2011, 07:55 PM   #34
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According to what I know:

Not all servos function exactly the same... some have a certain timeframe of 'memory'. So in between changes in position it may or may not hold previous position...it depends on how long the 'memory' is.

A servo with an internal framerate of 333hz will have less work to do if given a signal of a lower framerate for example at 200hz.

Its the same priciple as to why an analog servo might burn up when connected to a gyro set for digital.... but a digital will not burn up when gyro set for analog.

Something to consider is how many servos burn up because they were not running FBL blades or from binding or other setup issue?

I have a question: I notice on the align website that there are two listings for the same servo. They say it is the same but maybe some are old ones with lower frame rates? Maybe these are the ones burning up? I've set my cyclic with the 410's set for 200hz and shook the FBL unit like crazy to see how much heat is generated and didn't notice any excessive heat...I even did it with my finger resisting the arm. Maybe I have the newer servo? This is from a 450 pro combo kit I got in the summer and have flown a few months with no servo issue.
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Old 02-10-2011, 08:14 PM   #35
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Quote:
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Could servo failure has more to do with the servo in question?
That was the question I have raised also. In theory digital servos should be running from 300hz and up, whether the manufacturers short changed consumers is another question. For MB to set 200hz max limit on cyclic servos is a wise decision.
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Old 02-10-2011, 10:13 PM   #36
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I did some more reading ..... almost all RC receiver output signal to servo is at about 50-60hz. Unless the use of tail gyro which receives signal from rx at 50hz and increase the frame rate to whatever the gyro circuit is designed for, say 333hz which in turn drives the tail servo. I don't know if all fbl system cyclic sensors and circuit are designed to increase rx input of 50hz to higher frequency to drive the cyclic servos as tail gyro does.

May be not all FBL systems on the market raises the rx output. I know DJI, a highend auto system with GPS, self leveling system has servo input signal according to receiver output.
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Old 02-16-2011, 02:02 PM   #37
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Hitec replied my email on HS5625MG frequency request in 2 business days (333HZ). Spektrum did not reply at all after 5 days on DS821.
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Old 02-22-2011, 02:10 PM   #38
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Is there any chance we can get a list of acceptable Hyperion servo frequencies, namely the DS-09 SCD, and GMD and the DS-20FMD and GMD. I would post in the beastX forum, but mine has not arrived yet, so I dont know the SN to use during reg.
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Old 02-22-2011, 02:22 PM   #39
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Hyperion specs are listed here:

http://media.hyperion.hk/dn/at-ser/ATLAS-MAN-EN-PG2.pdf
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Old 02-22-2011, 04:50 PM   #40
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The Hyperion service send this answer:

Hi Rui,

All the Hyperion Servos (including the two you mention) can accept update pulses with a frequency from 20-400Hz.

Only full pulses are supported (center pulse ~1500 micro seconds).

I hope it help, if not, please let us know.


Thank you!

Hyperion EU RMA Dept.
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