Full-color, full-resolution graphics from the pages of QRP Homebrewer
QHB #10 -- April 2003
| Add a VCO to the Sniffer FSM for Audio Output, by Bob Johansen, WB2SRF |
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LM555 astable multivibrator generates audio frequency as function of the signal strength coming from the Sniffer’s meter driver stage. The greater the signal coming into the "Vactrol" Cadmium Sulfide photoconductive cell, its resistive element decreases and causes the 555 oscillator to increase in pitch |
