Is your martini olive transmitter collecting dust these days? Not any short range FM transmitter hidden in office brooms lately? Keyhole microphone or vibration microphone to hear whispers through wall of former days a memory now?
"Whistler" is shown in simulator circuit. An audio tone generator is connected to lamp or any two wire circuit in a room or wires leaving a room. We now turn microphone into speaker making audible sound to find hiding place. Not do inch by inch search of room.
Interesting was the old telephone receiver bugs hidden in telephone receiver handset. You call the number and before the phone rings you blow special tone on your harmonica to turn on bug and start listening in. Or call bugged phone and after they hang up blow harmonica tone to hear what is said about your call.
If microphone is hid in car you are tailing from a distance and sound grows weak change direction to get strong signal again and catch up to car.
Voice activated tape recorders not as common now.
Unfortunately world is growing less private and secure now.
