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Cast a beam of light on this device and presto! the announcer who over your radio has been setting forth at length upon the merits of this and that can be squelched effectively. A selenium cell is caused to operate a glow tube which in turn actuates a time lag contact breaker in the antenna circuit. Thus nauseating advertising blurbs are painlessly deleted from your enjoyment of otherwise fine programs |
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This is the circuit of Dr. DeForest's Anti-Ad. When the beam of light strikes the selenium cell (1) ; its resistance is lowered causing a voltage drop across the grid leak (3) and current to flow across the grid glow tube (2) operating the magnet (4) and breaking the antenna contacts (6). |
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Above are given the details for constructing the De Forest Anti-Ad, a device for automatically disconnecting the antenna for a prearranged time interval. Below is shown an alternative method of obtaining the time lag operation by means of various length pieces of tubing |