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Old 09-09-2010, 07:07 PM   #1
I am: Cedric V.
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Small Digital Dervos -

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What exactly would be the particular advantage of Digital Servos over Analogue for ordinary sport flying? Or even for so-called 3-D? I got a pair of Digital Micros off RCC a while ago and I can see no difference in speed on a servo tester and they are rated at the same torque as other servos their size (but they were a very good price!). Look to be in a HS-55 case too!
Now I see that Hitec have 'digitized' some of their nice smaller servos.
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Old 09-09-2010, 08:03 PM   #2
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Re: Small Digital Dervos -

I tried the Corona digitals a while back and they seemed to have a better resolution
than your typical analogue eg. HS-55 servo. Unfortunately, I no longer have a
canadian source for these.
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Old 09-09-2010, 11:41 PM   #3
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Re: Small Digital Dervos -

I believe that they hold thier positions better than analog servos. Depending on the Tx you have, you may not see much difference in the resolution.

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Old 09-10-2010, 06:24 AM   #4
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Re: Small Digital Dervos -

Here's how I understand it, though as usual, I may be totally wrong...

Only difference between digital and analog servo is the way it's handling the signal coming from the Rx. There's a microprocessor inside a digital servo that analyse the signal, and send information to the motor many time faster. End result is a motor (which would be the same one as in an analog servo) that speed up much faster, and being controlled by a processor, also give a more constant torque. So end result: faster servo and better at holding position. They also have a smoother acceleration.

So, digital is better for fast twitchy input variation (which is why you need a digital servo on a gyro, since gyro ouput VERY fast variation, faster than any human can do). It's also better for 3D and sport flying because they hold torque better. If you set them into one position, but the condition around the plane change, the control surface won't move as much as with an analog.
OK, I finally learned how to fly a RC plane... Next: Learning to land them, because this is getting costly...
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Old 09-10-2010, 07:00 AM   #5
I am: Cedric V.
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Re: Small Digital Dervos -

Thanks so far guys; yup R-G, that's what I figured the internal difference is and how it affects the "stiffness" of the servo but in spite of having designed PC boards, etched them and built servo amp boards using discrete components long ago, I must admit I'm still at a bit of a loss to understand how it can 'update the position of the motor 300 times a second' when the pulse from the Rx still only comes in at about 50 ppm.?
BTW: Servos have sure come a long way - the oldest in my possession is an old Futaba which has a five pin plug, still used a center tap on the battery and required a single cell tap for reference purposes and used a 3-ohm Copal motor!
P.S. I can see that it would take rather more sophisticated gear to measure holding torque and that, than I have at my disposal!

Last edited by Spitball; 09-10-2010 at 07:07 AM.
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