Newsgroups: comp.robotics
Path: brunix!sgiblab!swrinde!cs.utexas.edu!csc.ti.com!tilde.csc.ti.com!mksol!strohm
From: strohm@mksol.dseg.ti.com (john r strohm)
Subject: Tip for using R/C servos
Message-ID: <1994Feb8.192713.14923@mksol.dseg.ti.com>
Organization: Texas Instruments, Inc
References: <2j4krv$p3o@agora.rain.com>
Date: Tue, 8 Feb 1994 19:27:13 GMT
Lines: 13

At each servo, as close to the servo as you can manage it (i.e., shortest
possible lead lengths), put a LARGE electrolytic capacitor across the
+5 and GND leads.  I like ca. 250 uF, the value is not critical.

The reason for this is simple: the servo motor is seeing sort-of-PWM
kinds of signals while it is settling.  I measured steady-state currents
of 250 mA on a Royal Titan servo with the motor moving.  With the servo
"buzzing" (i.e., jittering about a position because of noise in the control
circuit), I was seeing 500 mA currents.

You can figure out what kinds of nasty stuff this is going to put back into
your logic supply if you don't do something about it.  Large electrolytic
capacitors are a cheap way out.
