Re: [mowbot] Servo positioning

adamdb nospam at
Mon, 2 Aug 1999 10:24:14 -0500

No they don't turn a full 180 on a 1-2ms pulse. 45 degrees in both
directions is typical. You can expand the pulse width from .5 to 2.5ms
and get greater travel, but your success in doing this may vary greatly
depending on the make and manufacturer of servo. You can also buy
"retract" servos which will give you a full 180 degrees with normal pulse
widths, but they are more expensive. The rate of turn should be
consistent for the entire travel of the servo, so I am guessing that the
circuit you are using is somehow causing the slow-fast rates you are


On Sat, 31 Jul 1999 19:17:24 -0400 "Michael Davenport"
<michael.davenport nospam at> writes:
> Can anyone tell me if servos are supposed to turn a full 180 degrees
> from a
> 1mS pulse to a 2mS pulse?
> I got the encoder and decoder circuits working I showed you - the
> 100K pots
> turn up to 9 servos, but they only turn about 45 degrees.
> Furthermore, they
> turn very slowly for the first quarter turn, then turn very quickly
> for the
> last 3/4 turn.
> The servos I'm using are very inexpensive, Futaba S3003 's. Will
> they turn
> a full 180 degrees if the pulses are correct?
> Michael Davenport

Adam Bryant (age 0x23)
abryant nospam at (work)
adamdb nospam at (home)
Parker, CO, USA
Robotics, RC Airplanes, anything using a PIC

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