
K1EL
Morse Code Practice Oscillator
CPO
CPO Datasheet – A.3
4/10/2020
Page
16
A Word or Two Regarding USB Phone Charging Batteries
These are generally not suitable for use with the CPO. Most require a minimum current
draw of about 100 mA, if this is not met, they will shut off automatically. Unfortunately
this current level is far above the CPO idle current. What usually happens is the charger
will run the CPO for about 5 minutes and then shut down. We have found some charging
batteries that will provide power indefinitely but the majority won’t. To get around this, a
ballast resistor (R6) can be populated on the CPO board to boost the CPO current draw
but this is not recommended because it wastes power, reduces battery life, and
generates excess heat. Just say no….
Support and Warranty Information
The CPO is fully warranted to the original purchaser by K1EL Systems against defects in
materials and workmanship for one year after purchase. This warranty does not cover
damage caused by accident, improper assembly, or lightning damage. Please contact
us before returning your CPO for repair and we will issue an RMA. Please submit
questions by e-mail to
Watch our website for latest updates and new products:
http://www.k1el.com
While every effort has been made to insure that the CPO design is as complete
and safe as possible, it is still possible to cause equipment damage or incur
personal injury if:
1) The CPO kit is not used as intended.
2) Is connected incorrectly.
3) Safety guidelines outlined in this document are not followed.
4) The CPO kit is modified in any way.
K1EL Systems LLC cannot be held responsible in these or other similar events
Revision History
CPO Data Sheet
A.1 Initial release
A.2 Several minor typo corrections
A.3 Incorporated changes for Rev 6 PCB
a) Component change to make speaker audio gain range more linear
b) Increased Line Out level range
c) Rotated line out trimmer for easier access.
CPO PIC Firmware Revision
Rev A Original Release