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The Privacy Box by Lucky225 S2 R2 --------|---------------------- / ---\/\/\/\/--| (ring, red -) | > | < r3 | > (+) | <---------- < <telephone> > ----------- < r1 | (-) > | | | / S1 | | | (||)led | ---------|------------------------------------| (tip, green, +) r1= ~68ohm r2= ~470ohm r3= ~220ohm led= 1.7v in use= in use light circuit phone= phone s1 = switch s2 = switch Use: If another extension is picked up you can press S1 for privacy mode, this will put a 68ohm resistor in parallel with the phone line to create low voltage, about .5 volts, not enough to light the led. When in privacy mode it will be very hard to hear any of the parties on your line. The led will light when the person on the other extension hangs up because the voltage will go to .7 volts causing the led to glow just lightly. then you can turn S1 off to talk normally. (Hint: depending on the resistance of your particular phone, the circuit may not work propertly, try changing the resistance from 22-68ohms or different voltage rated led's to troubleshoot) S2 is a switch to turn on the "invisible box" which will make in-use lights and telephone recording devices that record when an extension is off-hook in-operative. (Also, resistance is variable, try changing resistors if it doesn't work)