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PLL_CODE_PRACTICE_OSCILLATOR

2016-08-18 17:36  
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PLL_CODE_PRACTICE_OSCILLATOR
This CPO usesa 567 phase-locked loop, IC1, as the variable tone generator. The oscillator's frequency is set by R6, and the frequency range can be changed by selecting a different-value capacitor for C5. To lower the oscillator's frequency range, make the value of C5 larger, and to increase the frequency range, reduce C5. A general-purpose 2N3906 PNP transistor, Q1, supplies power to the 567 through pin 4 each time that the CW key is closed. Meanwhile, Q2, a general-purpose 2N3904 NPN transistor, buffers the oscillator's output and drives the speaker. Potentiometer R7 sets the output volume.