Ramsey CPO3 User Manual

CODE PRACTICE
OSCILLATOR KIT

Ramsey Electronics Model No. CPO3

Ever wanted to hone your code skill but didn’t have an easy
way to practice? This handy little kit will allow you to tap away
anywhere you happen to be! Small enough to fit into your
pocket or briefcase, you can take it anywhere. You’ll find
yourself up to speed in no time!

• Great starter kit

• Ideal for Boy Scouts

• Perfect first electronic kit for schools

• Increase your code speed . . . practice anywhere.

• Easy one evening assembly

CPO3 • 1

PARTIAL LIST OF AVAILABLE KITS

RAMSEY TRANSMITTER KITS

• FM10A FM Stereo Transmitter

• FM25B Synthesized FM Stereo Transmitter

• AM25 Synthesized AM Transmitter

• AM1 AM Transmitter

RAMSEY RECEIVER KITS

• FR1 FM Broadcast Receiver

• AR1 Aircraft Band Receiver

• AA7 Active Antenna

• SC1 Shortwave Converter

RAMSEY HOBBY KITS

• SG7 Personal Speed Radar

• SS70 Speech Scrambler

• TT1 Telephone Recorder

• SP1 Speakerphone

• MD3 Microwave Motion Detector

• PH10 Peak hold Meter

• LC1 Inductance-Capacitance Meter

RAMSEY AMATEUR RADIO KITS

• DDF1 Doppler Direction Finder Kit

• HR Series HF All Mode Receivers

• QRP Series HF CW Transmitters

• CW7 CW Keyer

• QRP Power Amplifiers

RAMSEY MINI-KITS
Many other kits are available for hobby, school, scouts and just plain FUN. New
kits are always under development. Write or call for our free Ramsey catalog.

CODE PRACTICE OSCILLATOR KIT INSTRUCTION MANUAL

Ramsey Electronics publication No. MCPO3 Revision

COPYRIGHT

14564. All rights reserved. No portion of this publication may be copied or duplicated without the
written permission of Ramsey Electronics, Inc. Printed in the United States of America.



1994 by Ramsey Electronics, Inc. 590 Fishers Station Drive, Victor, New York

First printing: January 2001

CPO3 • 2

Ramsey Publication No. MCPO3

Manual Price Only $5.00

INSTRUCTION MANUAL FOR

CODE PRACTICE
OSCILLATOR KIT

TABLE OF CONTENTS

Introduction .................................... 4

Circuit Description .......................... 4

Schematic Diagram ........................ 5

Parts Layout Diagram .................... 5

Parts List ........................................ 6

Identifying Kit Parts ........................ 7

International Morse Code ............... 8

Assembly Instructions .................. 12

Testing ......................................... 14

Conclusion ................................... 14

Ramsey Kit Warranty ................... 15

CPO3 • 3

RAMSEY ELECTRONICS, INC.

590 Fishers Station Drive

Victor, New York 14564

Phone [phone]

Fax [phone]

www.ramseyelectronics.com

INTRODUCTION

Morse Code has been used since 1837. It was originally used for telegraph
communications and was the first method used for radio communications.
For many years, Morse Code was required knowledge for any shipboard
radio operator. In 1910, the Titanic was the first ship to use the international
distress call SOS. Until recently, code proficiency was required for all
amateur radio licensees and was even required by the Boy Scouts. It still is
required for the Signaling merit badge. The CPO3 is a fun, educational kit for
any skill level builder and can be used to introduce anyone to this historic
means of communication.

CIRCUIT DESCRIPTION

As the key is pressed, providing the circuit a ground path and starting the
cycle, two things happen. C1 starts to charge via R1, R3 and R4. At this time
the output of pin 3 is high. When the voltage on C1 reaches 2/3 of the supply
voltage, the output of pin 3 will go low and pin 7 is grounded, starting the
discharge cycle. The capacitor is discharged through R1. When the voltage
on C1 reaches 1/3 of the supply voltage, the output at pin 3 goes high and
pin 7 is no longer at ground. This starts the charging cycle again.

Timing is completely independent of the supply voltage used. It is determined
by the values R1, R3, R4 and C1. The formula for the total time (T) of a
complete cycle is:

T = 0.693[(R3+R4+2R1)C1].
The component values provided allow a range of 1300 Hz to 1700 Hz. The

key is attached to pin 1 and provides the kit with a ground connection,
completing the circuit and turning the entire unit on. The key is basically an
on/off switch. Capacitor C2 filters out noise and R2 is a current limiting
resistor for the speaker, SP1.

CPO3 • 4

PARTS LAYOUT DIAGRAM

CPO3 • 5