Code Practice Oscillator
A good first project for the amateur radio operator is the Code Practice Oscillator. It is beneficial for two reasons:
It is a simple circuit that will help the new ham get hands on experience assembling his own gear.
The completed oscillator will allow him to practice sending code.
The most common code practice oscillator circuits seen today are based on the 555 timer IC.
Here is a typical circuit you can construct with just a handful of parts still easily obtained at RadioShack.
Here's what you will need, all part numbers are RadioShack and prices as of 10/16/2008:
PART STOCK NO PRICE
C1 22uF Electrolytic Capacitor 272-1026 $ 1.19
C2 0.022 uF Capacitor 272-1066 1.49
IC1 555 Timer 276-1718 1.69
R1 10K Ohm Potentiometer 271-1721 2.99 tone control
R2 2.2K Ohm Resistor 271-1325 0.99
R3 5K Ohm Potentiometer 271-1714 2.99 volume control
SPKR 8 ohm Mini Speaker 273-092 2.79
9v DC battery clip 270-325 1.99 9vDC battery 23-875 4.49
Pre-Punched Perfboard 276-1395 2.79
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TOTAL COSTS, REQUIRED PARTS $23.40
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OPTIONAL
1/4" Mono Audio Jack 274-252 $ 2.99 (for key)
Project Enclosure (6x4x2") 270-1806 4.99
Hexagongal Control Knob, 2 274-407 1.99
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TOTAL COSTS, OPTIONAL PARTS $ 9.97
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Construction Tips:
- Cut perfboard to fit in one of the slots in the 270-1806 project enclosure, if used.
- Lay out of parts is not critical, use jumper wires to connect components as needed.
- R3 can be omitted and a fixed carbon resistor may be used. 5K - 20K ohms should work well - feel free to experiment.