Copyright © Parallax Inc.
Parallax Continuous Rotation Servo (#900-00008)
v2.2 10/24/2011 Page 2 of 8
Device Information
The Parallax continuous rotation servo relies on pulse width modulation to control the rotation speed and
direction of the serv o shaft. Before u sing the servo in a project, it is important to c alibrate the center
position of the servo in order to defi ne the pul se width value at which the servo holds still (see the
section Calibration – "Center" the Servo on page 4).
Specifications
Pin
Name
Description
Minimum
Typical
Maximum
Units
1 (White)
Signal
Input; TTL or CMOS
3.3
5.0
0.2
V
2 (Red)
Vservo
Power Supply
4.0
5.0
6.0*
V
3 (Black)
Vss
Ground
0
V
*
See Board of Education Servo Header Connection Diagram.
Power Precautions
Do not use this servo with an unregulated wall-mount supply. Such powe supplies may deliver
variable voltage far above the stated voltage.
Do not power this servo through the BASIC Stamp
®
Module's Vin pin, this can deliver voltages
above the stated voltage. See the Board of Education Connection Diagram below for jumper
settings.
Servo current draw can spike while under peak load; be sure your application's regulator is
prepared to supply adequate current for all servos used in combination.
Board of Education Servo Header Connection Diagram
When connecting the servo to the Board of Education
®
servo header, be sure the jumper is set t o Vdd
(regulated 5 VDC for this board) as shown in the figure below. Failure to place the jumper at this setting
can cause damage your servo! (Note: see the Board of Education product documentation for instructions
regarding earlier board revisions that do not have a servo header with a jumper.)
Black
Red
X4 X5
15 14 13 12
Vdd
Vin
Using a Separate Power Supply on a HomeWork Board
The BASIC Stamp HomeWork Board uses a 9 V battery for a power supply. A servo can drain a fresh 9 V
battery in under 20 minutes! Foll ow these directions to build two servo p orts on the breadboard, and
power them with a separate battery pack.
Hardware Required
(1) BASIC Stamp HomeWork Board (serial #555-28158 or USB #555-28188)
(1) Battery pack with tinned leads (Parallax #753-00001)
(2) Parallax continuous rotation servos
(2) 3-pin male-male headers (Parallax #451-00303)
(4) Jumper wires (10-pack: Parallax #800-00016
(4) 1.5 V AA batteries
