hopefully somone can give me a little education on this.
Been out of the hobby for 12 years.....back before digital servos were around.

I fly 1/4 scale 40-100cc sport scale and am considering either Hitec 985MG (analog) or 5985MG(digital)
both have the same specs ie: torque,speed,current draw,weight
so many questions.......
is there any reason to use one over the other?
can I just plug a digital into my receiver? Using Spektrum DX7 radio system
do I need to program the programmable feature on the digital?
I am running 5cell 6 volt receiver packs, is that any cause for concern?

sorry for all the questions. Back in the day we just plugged servos in and flew. MAYBE you bought a big honkin' giant scale servo for your rudder back then

Hello Sodbuster.

Let me see if I can answer some of your questions. You're already familiar with analog servos, from 12 years ago, so no need to go into those.

The newer digital servos have a lot going for them. Their main assets are high torque, and the ability to maintain their under load, that is, if you deflect the servo "x" degrees, it will maintain that setting despite loads, and are much more precise. The con's are that they generally cost more and use more current, so a larger capacity battery pack is needed. Most upper end servos can run on 4.8 and 6.0V

A typical use for programmable servos would be, say, if you ganged 2 or 3 servos on one control surface, such as an aileron. You can program all three servos so that they all have the same end points, neutral points, etc. This way, they're not fighting each other.

I hope this might start a discussion going that will clarify things a bit more for you.

Bob

Here is an article from Futaba. [link=http://www.futaba-rc.com/servos/digitalservos.pdf]Futaba PDF file[/link]

Have a look at this too- http://www.rcuniverse.com/forum/m_49...digital/tm.htm

Only Hitech servos are programable. And it takes a special programer. Spend time comparing servos at Tower you will find they have lots of different features. Probably the most common GS servo is the Hitech 5955. It has a coreless motor, Titanium gears, very small centering dead zone. And the gears stay tight for what seems forever. It is programable. It can be used in just about any plane. Futaba and JR have recently come out with servos with more torque but for me, I'd just use two 5955s in stead.

Futaba,JR, Hitech and most all others plug into dx7 recievers. With Futaba you will need to snip off the tab.

Digital Servo FAQ - Hitec answers
Good video demonstrations:
Digital Servo Instruction Videos - HFP-10 programming
the following may also assist with choices:
Hitec HFP-20 - New Servo Tester_Programmer for Hitec G2 digital and other servos
101 - Servo FAQ & picking the right servo for the job
Regards
Alan T.
Alan's Hobby, Model & RC FAQ Web Links

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