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My CW Practice Oscillator Project:

I obtained a Bunnell & Co. Signal Corps 1942 keyer, aka bug, at an estate sale. Not sure if it came from a ham or a military radio person. There was no other radio equipment in the house.

Cleaned it up, it looks pretty good and decided to try my CW ‘fist’ using an 80 year old key.

I did not save any CW practice oscillators (tone generators) from my past and needed to find, or build one.

Here’s the results:

CW practice oscillatorIC-555 TIMER

This is the classic tone generator using an IC-555 timer chip. I did not make one of these not having the IC-555 chip. There are many examples of this circuit on line.

Here is the ARRL’s CW Practice Oscillator Kit schematic. A working example is WIP.

Reference:

Code Practice Oscillator from ARRL Now You’re Talking, pp. 11-1 to 11-2
Copyright 1990 by the American Radio Relay League, Inc. All rights reserved

CW OSCILLATOR #1

CW Practice Oscillator astable multivibrator

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This was a bit tricky to get it to oscillate. Ended up with a 10 uF capacitor.

The tone is very harsh and very LOUD. Not very pleasant  use.

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CW OSCILLATOR #2

(ASTABLE MULTIVIBRATOR)

Similar circuits to this exist all over the internet and this one proved to be easy to get to oscillate and had a nice pleasant tone.

I will be adding more information as I experiment with different capacitor and resistor sizes. Also wish to add a volume control.

Revisions:

  • R1, R3 47K makes for a cleaner tone.

References:

  • The schematic for CW Oscillator #1 source has been misplaced and i will added if/when found.
  • The schematic for CW Oscillator #2 came from the bipolar cookbook part 2 ( Link ).
  • Solid State Design for the radio amateur, ARRL, 1977 p 174.