
K1EL
Morse Code Practice Oscillator
CPO
CPO Datasheet – A.3
4/10/2020
Page
2
Features
•
Keyed sine wave oscillator with wave shaping
•
Volume control
•
Frequency (pitch) adjustment control approx. 400 Hz to 1800 Hz
•
RTTY test tone generation mode (2125/2295 Hz)
•
Pushbuttons allow easy keying and FSK for testing purposes
•
Internal low volume speaker for quiet practicing
•
1/8” external speaker/headphone output jack with ½ watt output
•
LED keying indicator lamp
•
1/8” stereo key input jack (Key/FSK)
•
1/8” audio line output jack adjustable 0 to 500 mV 5K impedance
•
Mini-USB 5 volt power connector (power only, not data)
•
Custom metal enclosure with stick on label
Description
The CPO is a versatile code practice oscillator with synthesized sine wave output and
adjustable frequency and volume controls. A 1/8” input jack is provided to key the
oscillator from practically any keyer or straight key. Note that the CPO does not have a
built in keyer, it is only a tone oscillator. A single chip microcontroller provides all of the
functionality of the CPO including sine wave generation. It is implemented in a Microchip
PIC12F1501 single chip microcontroller. An LM386 provides a higher drive level for an
internal speaker, external speaker, or headphones. A red keying pushbutton is provided
to manually key the oscillator for testing purposes. When the frequency (pitch) control is
set fully clockwise, RTTY test tone mode is enabled. When RTTY mode is active the
tone frequency is fixed at 2295 Hz. Asserting the FSK input (or pressing the black
pushbutton) will frequency shift the tone down to 2125 Hz.
Enclosure Label
Due to the extremely high cost of enclosure design and fabrication, we are changing the
way we use them. In the past we would offer a custom enclosure with silkscreen for
each product that we introduce. To continue this, we would have to double the price of
our products. So going forward, we are designing one enclosure for multiple products
and customizing them with a good quality stick-on product label. Following the trend in
pro-audio gear, we place this label on top of the unit. This has an advantage in that you
can see where rear connector plugs go without having to turn the unit around to look at
the rear panel.
I am mentioning this here because we want to be up front with this new process and not
surprise anyone.