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<blockquote data-quote="Vipersan" data-source="post: 853051" data-attributes="member: 325666"><p>Only one correction CH ..</p><p>The OC71 was a transistor ...I think OA91 was the glass diode ..correct me if I'm wrong</p><p>If memory serves glass encapsulated germanium & arsenic doped ..and coated in black paint..</p><p>Which was easily scraped off ..</p><p>Which led to some very interesting experiments ..when placed at the focal point of a dish shaped reflector..</p><p>Now with an oc71 as a receiver detector at the input to an audio amp ..and an audio modulated light source it was possible to cover up to about a 1/4 mile direct line of sight ..and you had your own private coms system..</p><p>Eventually modulated audio onto an VLF subcarrier ..and doubled the effective distance partcularly effective at night..in days before severe light pollution</p><p>Pointing the ahem ..receiver at street lights produced an audible hum ...and a hiss if pointed at the sun.</p><p>Happy days..</p></blockquote><p></p>
[QUOTE="Vipersan, post: 853051, member: 325666"] Only one correction CH .. The OC71 was a transistor ...I think OA91 was the glass diode ..correct me if I'm wrong If memory serves glass encapsulated germanium & arsenic doped ..and coated in black paint.. Which was easily scraped off .. Which led to some very interesting experiments ..when placed at the focal point of a dish shaped reflector.. Now with an oc71 as a receiver detector at the input to an audio amp ..and an audio modulated light source it was possible to cover up to about a 1/4 mile direct line of sight ..and you had your own private coms system.. Eventually modulated audio onto an VLF subcarrier ..and doubled the effective distance partcularly effective at night..in days before severe light pollution Pointing the ahem ..receiver at street lights produced an audible hum ...and a hiss if pointed at the sun. Happy days.. [/QUOTE]
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