DC Phantom
Simple DC signalling can be achieved on a telecommunications line in a similar way to phantom powering of microphones. A switch connected to the transformer centre-tap at one end of the line can operate a similarly connected relay at the other end. The return path is through the ground connection. This arrangement can be used for remotely controlling equipment.
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Famous quotes containing the word phantom:
“It was a favor for which to be forever silent to be shown this vision. The earth beneath had become such a flitting thing of lights and shadows as the clouds had been before. It was not merely veiled to me, but it had passed away like the phantom of a shadow, skias onar, and this new platform was gained. As I had climbed above storm and cloud, so by successive days’ journeys I might reach the region of eternal day, beyond the tapering shadow of the earth.”
—Henry David Thoreau (1817–1862)