CanadaKim Posted April 14, 2021 Share Posted April 14, 2021 Interesting ghost receiver that uses a opto-isolator How to Make a Ghost Detector Circuit | Homemade Circuit Projects (homemade-circuits.com) 2 Quote Link to comment Share on other sites More sharing options...
Andres Ramos Posted July 9, 2021 Share Posted July 9, 2021 Just saw this post and I instantly remembered this circuit from a book I read in the 70s until the pages of it disintegrated. It described electronic circuits for surveillance applications, mainly electronic bugs, and the circuit you showed was used to switch on a bug when someone entered the room. I checked this out years ago and it exactly worked as you described it. 0 Quote Link to comment Share on other sites More sharing options...
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