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Micro servo digital or analog?

Geronimo

Active member
#1
I just got 3 new Micro servos that the guy that gave them to me says he thinks are digital. All they say is "Tower Pro MG90S Micro Servo"

Is there any way to tell for sure without taking them apart?

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Geronimo

Active member
#4
According to the Banggood web site the MG90S is analogue.
It really appears there are many different servos that look nearly the same.

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=MG90S+Digital&_sacat=0

So then I found this Youtube that only makes matters more confusing


He says all these servos are copies of copies... and it's really hard to tell which one is good or just plain cheap. So... since I got them for free, I'm going to open one up and have a look. I had an analog servo go bad just 30 seconds into it's first flight because the potentiometer was garbage. I thought a plastic gear had lost a tooth (the first gear connected to the motor output gear) but that didn't prove to be the case. I'll take some pictures and see what I can find out.
 

Geronimo

Active member
#5
So from what I gather, both the digital and analog versions use a potentiometer as a position sensor. The only real difference is that the analog servos have a 50Hz signal and the digital have a 300Hz signal which improves the servo response speed. Also, almost all servos made today are digital. The only way to know for sure is to open the servo and look at the amplifier board at the base of the servo, and see if it has a processor. It's going to be difficult for most people to discern between a processor and an ASIC chip which the analog servos have.

In the end, the digital servos are only slightly better than the analog... so that's why there isn't a big push to change over. What people really seem to want is a durable/reliable servo that weighs almost nothing and costs almost nothing.
 
#6
These are the only servos I buy - I probably have 40 or 50 of them in planes and I've never had one go bad except for wires getting pulled out in a crash or cut with a prop in combat. My source for these has always been banggood, so if there are multiple copies of copies, at least the ones they get are some of the better copies. Pricing is slightly higher than $2 right now, which is still good, but I keep them on my wishlist and every time I make an order I check for a good sale (on this and everything else in my wishlist).
 

Bricks

Well-known member
#7
Digital servos will will center better, hold position better and normally much quicker to respond to inputs more precisely, higher resolution is what makes this all possible. Pilots that do 3D do not spend as much as 3-4 times for good digital servos over analogs just because they want to waiste money, they are not the same.
 

Geronimo

Active member
#8
Digital servos will will center better, hold position better and normally much quicker to respond to inputs more precisely, higher resolution is what makes this all possible. Pilots that do 3D do not spend as much as 3-4 times for good digital servos over analogs just because they want to waiste money, they are not the same.
My guess is that some of the digital servos use a good quality position sensor rather than a potentiometer. Even a high quality potentiometer would go a long way. If a servo won't center, that's some crappy electronics no doubt.