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A quick follow-up to How can I tell the frequency without an oscilloscope, or frequency counter?

My supply is a transformer plucked from a dead power adapter rated for 1.5A. This is rectified cap-filtered, then Vo manipulated through an LM317 with a pair of 1k linear.

I plan to tap the capacitor output to power the oscillator, and use the 317 output to bias the varactor.

Does the varactor bias supply have to be distinct from Vcc?

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1 Answers1

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No, you can derive the bias from Vcc just fine. You will want to make sure the bias voltage is well-regulated and low-noise, since any error or noise will be manifest in the tuning of your radio. Nothing that can't be accomplished by a voltage regulator and a bit of filtering, however.

Phil Frost - W8II
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