[NSRCA-discussion] Futaba Servos

[Ed Miller]

I've used unregulated 5 cell NiCad's or NimH packs on just about every 
Futaba servo ever made over the last 12 or so years with no problems.  Even 
the servos Futaba only "rate" at 4.8 volts.  I can't speak for the new 
brushless digitals but from a consistency point the regulator is the way to 
go.
Ed M.
----- Original Message ----- 
From: "Ed Alt" <ed_alt at hotmail.com>
To: "'NSRCA Mailing List'" <nsrca-discussion at lists.nsrca.org>
Sent: Friday, January 11, 2008 8:20 AM
Subject: Re: [NSRCA-discussion] Futaba Servos


Jay:

I'm guessing that they may be trying to convey that that you ought to use a
4 cell pack, i.e., it's another 4.8V rated servo most likely.  If that's the
case, it really comes down to the fact that you can operate it up to about
5.5V without busting their limit, since that is about where a freshly
charged 4 cell NiCad will be.  It's also possible that they don't think
highly of NiMH packs, since many of these have high internal impedance and
could affect servo performance under some conditions.



Regardless, all the servo "sees" is the voltage at it's input, regardless of
how it was produced and all it "wants" is adequate current no demand,
without adversely affecting the voltage at the same time.  So in reality, a
good LiPo and a good regulator will work better than a NiCad.  You could use
the Jaccio or the one I make if you like to have the adjustable output
capability.  Either works better than a 4 cell NiCad in a Pattern
application.  If you need a voltage range lower than what I normally
produce, that's not a problem.



Ed



-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Jay Marshall
Sent: Friday, January 11, 2008 8:08 AM
To: nsrca-discussion at lists.nsrca.org
Subject: [NSRCA-discussion] Futaba Servos



I am planning to use the new Futaba BLM 451 servos in my new plane. I had
also planned to use a 2S LiPo battery and Castle Creation's new BEC for the
system power. The servos, however, have a note on the box "Ni-Cd Use Only"
Does anyone know why? I can't find any reference to this spec on the Futaba
site (although I might have missed it).



Jay Marshall






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