Radio News, September, 1930, pages 215, 285:
 
sample use
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
figure 1
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).

By  Dr.  Lee  DeForest

    THE tendency of the present radio broadcast programs degenerate more and more into crass commercialism and to devote a steadily increasing proportion of the time to exploiting the merits of every conceivable commodity from tooth-paste and cigarettes to household furniture and diamond rings is steadily diminishing the number of radio users or the hours for which the radio sets are turned on. One tires of continually getting up from his easy-chair every little while and going over to the dial, shutting off the set, or tuning it to another station as soon as the music of a program ceases and the blatant advertiser begins to announce his wares. So many of the best musical programs are nowadays more and more interrupted by these utterly uninteresting selling blurbs that although the radio listener realizes that in a few minutes, if he can endure the nuisance, the enjoyable part of the program will be resumed, he tires of continually running from his seat across the room to the radio set, and finally in disgust turns off the set altogether.
    The remote control sets which are now coming into the market are enjoying ever increasing popularity, for which the advertising nuisance is largely responsible, offer one solution to the difficulty. But the nuisance of having a cable stretched across the room from the set to the easy-chair and the reading lamp, over which the missus and the children invariably trip, is a distinct disadvantage.
    What the long-suffering radio user needs is a simple wireless device whereby he can instantly assassinate the advertising announcer and allow the set to resume its musical outpourings when the story of the tooth-paste or furniture salesman is terminated.
figures 2,3,4
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
figures 2,3,4

    The "Anti-Ad" device perfectly solves this problem. It consists of a small metal box approximately 6" square and 4" high which can be placed on top of the radio receiver or anywhere near it and is connected to the latter by a short flexible conductor cable. The "Anti-Ad" contains a selenium cell and a "grid glow" relay tube and simple relay. The selenium cell is set in the small end of a funnel-shaped shadow box so that it is not affected by daylight or the ordinary diffused lamp-light in a room. The current for energizing the selenium cell, the "grid-glow" tube and the relay is all supplied from the radio set through the two-conductor cord which is connected to a two-contact disc which is fitted over the plugs of the detector tube, and the tube is then plugged back into its socket. The antenna is taken direct to a binding-post on the back of the Anti-Ad and a lead from the second binding post on the same leads to the antenna binding post on the radio set. The relay acts to break the contact in the aerial, thus cutting off all incoming energy from the radio set.
    All that the discriminating and ad-exhausted radio listener needs to have at hand in order to operate the Anti-Ad is a small flashlight, which can be had in very ornamental form, located within easy reach on the table or chair where he or she is seated. When the musical program ends and the advertising agony begins, she merely picks up this flashlight, presses the button, aims this spot at the shadow-box on the Anti-Ad and presto! the relay operates, the antenna is cut off and our friend Mr. Radio Advertiser is talking into empty space, as he should be.
    It is not necessary to hold the spotlight focused on the selenium cell throughout the desired period of interruption of radio set because attached to the relay is a time lag device which permits the relay to return to contact only after a definite period of delay. The duration of this period of delay is adjustable by means of the knob and dial on top of the Anti-Ad which is calibrated in seconds. Thus, for example, if the radio listener knows that the "Third Strike Cigarette" announcer invariable talks for 20 or 30 or 45 seconds before permitting his excellent orchestra to resume their work, she can at the opening of the "Third Strike" program set the dial to say 40 seconds. Then when the announcer begins to tell the health benefits of his cigarette she gives one quick flash of her spotlight onto the Anti-Ad and can resume her reading in peace of mind, knowing that at the end of the 40 seconds the relay device will be released and the program will go on. It is possible that she may miss a few bars of the selection or possibly, if the advertiser is unusually windy, she may catch a few final words of his speech, but the peace of mind of the radio listener will be immeasurably conserved.
    In using the Anti-Ad one experiences a new joy not unlike that which one would experience in shooting a noisy tom-cat on the top of a back fence on a moonlight night and thus terminating the awful caterwaul. It is infinitely more satisfactory to recline in your easy-chair and kill the announcer with the simple flash of light than it is to get up, walk across the room and throw the radio switch.
    The Anti-Ad adds to real radio enjoyment and greatly extends the number of hours throughout the month when the radio set is in operation. It should therefore be received with open arms by the entire radio industry.