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HomeAircraftHelicopterRadio - Spektrum DSM › dx8 difference between 11ms and 22ms.
06-02-2012 04:56 PM  6 years agoPost 1
Busher

rrKey Veteran

Manchester, England

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Hi there.

Can anybody explain to me what effect changing the the frame rate on the TX has on the overall set up i.e what effect this has on the full setup from the TX to the servo.

I have just smoked a couple of servo's and i think it is because I set the wrong TX frame rate, I was foolish to think this would not effect the servo end, so I may have the wrong idea on how all this works.

The servo's I was using were quoted as digital so I thought it would be OK, but 1 let the smoke out and the other 2 got so hot I am reluctant to use them.
Any pointers would be good.

Thanks

Good luck
Busher

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06-02-2012 05:29 PM  6 years agoPost 2
TMoore

rrMaster

Cookeville, TN

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11ms is usually reserved for digis. Probably defective to start with.

Delayed Response Operator Not Engaged
AMA SECTION 336 = Good
Drones = EVIL

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06-02-2012 06:06 PM  6 years agoPost 3
jschenck

rrProfessor

La Vista, NE.

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what servo models were those that got cooked? I kind of doubt it was due to running at 11ms frame rate but it's possible. could they have been in a bound up position, like the servo wheels were installed in a position where the servos were not centered when putting the wheels on?

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06-03-2012 08:58 AM  6 years agoPost 4
Busher

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Manchester, England

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The servo's were a cheap set from HK they were HK scm9-6, they are a good servo for the price but not what I would call a quality servo. It is just that they fitted the heli perfectly. I have used these servo's in parkfly and other models without issue,

Now you could be right about binding them up, as they did run to the end stop but that would be a first for me as I have never had a set go like that in just a few seconds, as I disconnected the flight pack almost the same time as I saw them run to the end stop. Most other servo's that were bound up usually last a bit longer and give a bit more warning etc.

They are stated as single chip digital servo's but as I say I am at a loss as to what the difference in frame rate has on the overall set up of the system. And how this effects what the servo gets for a signal etc. That may help me understand whether setting the 11ms has shot the servo or not.

As a side line I have just set the same servo up on a gyro and set the output to 1520 333mhz and the servo seems very happy, am I barking up the wrong tree here or are the settings unrelated?

Thanks for your help up to date

Good luck
Busher

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06-03-2012 12:48 PM  6 years agoPost 5
Heli 770

rrProfessor

USA.

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Busher
Only the cyclic servo channels are 11ms when switched to 11ms, everything else stays at 22ms.

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06-03-2012 01:41 PM  6 years agoPost 6
Pistol Pete

rrProfessor

Seffner, FL

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FRAME RATE
The "time" a servo expects to have its CENTERing signal refreshed.

For analog servos the average is 20ms @ 50Kz (50 pulses per minute)

The higher the frame rate the faster it respond.(ie: DIGITAL)
Tail servos usually have the highest frame rates thus the fastest.

You must use the recommended frame rate for the servo as well as voltage input.

A "too high" frame rate can confuse the servo while a "too low" will reduce its holding power, speed and or precision. The indirect answer to your question.

A "second" is an eternity when it comes to electronics given measurements are usually in the micro/pico units. Faster than the blink of an eye is what it takes to smoke anything...unfortunately.

~~Enjoying the hobby one flight at a time~~

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06-03-2012 05:39 PM  6 years agoPost 7
Busher

rrKey Veteran

Manchester, England

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Only the cyclic servo channels are 11ms when switched to 11ms, everything else stays at 22ms.
Thanks that explains some of it.

Good luck
Busher

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06-03-2012 05:56 PM  6 years agoPost 8
Busher

rrKey Veteran

Manchester, England

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I am not really convinced that the time stalled, was sufficient to smoke the servo,if so I would have a lot of burn't servo's and these are the first I have burnt, but I could be wrong. I do agree that the frame rate could have done the damage to the servo.

Is there a possibility that the combination of both the frame rate and a stall could have just been too much overall?

Looks like I should run the servo's on 22ms and check for binding at all ends as I usually do, I guess I could have just been unlucky and had a bad set up and at the wrong pulse as well, the bad set up is completely my fault as I should not have had the arms connected till centre was established, The frame rate sent to the radio was selected by me and possibly the servo did not like it. I can only bench test another servo when I get the chance and see if the servo burns out when 11ms is selected. Hell they are only a few bucks each but I always try to learn from a mistake and find out why.

Good luck
Busher

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