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They looked at him questioningly for a moment, but he smiled reassuringly at them and they, having learned that he never used that dread shock-rod on them, all went back to their labors, leaving the one native standing there. Hanlon looked earnestly at the Greenie, pointed a finger directly at himself and spoke into the microphone of his transformer.
This latter device may be either a telephone induction coil, a microphone transformer, or a magnetic modulator; the first two of these devices step-up the voltage of the battery current and the amplified voltage thus developed is impressed on the oscillations that surge through the closed oscillation circuit or the aerial wire system according to the place where you connect it.
The filament terminal takes a current of 7.5 volts and this is supplied by another secondary coil of the transformer. This rectifier tube delivers a direct current of 20 watts at 350 volts. The price is $7.50. The Filter Condensers. These condensers are used in connection with the reactance coil to smooth out the pulsating direct current after it has passed through the rectifier tube.
It is the mutual induction that takes place between two coils of wire which makes it possible to transform low voltage currents from a battery or a 110 volt source of current into high pressure currents, or high potential currents, as they are called, by means of a spark coil or a transformer, as well as to step up and step down the potential of the high frequency currents that are set up in sending and receiving oscillation transformers.
The service lines are on poles and extend over a large area. Nature has no regard for the convenience of either the company or its patrons. A thunderbolt may knock out a transformer, or a tree may be blown down and carry nearby electric lines with it. Repair men are continually on the job with a well-run company and work speedily and faithfully but they cannot be everywhere at once.
The principal pieces of apparatus for this transmitter are the same as those used for the 100 Mile Continuous Wave Telegraph Transmitting Set described and pictured in the preceding chapter which used direct current, except that an alternating current power transformer is employed instead of the more costly motor-generator. The Apparatus Required. The Choke Coils. The Milli-ammeter.
This shows Mr. The Alternating Current Power Transformer. Like the smaller one, however, it is made to work with a 50 to 60 cycle current at 102.5 to 115 volts and, hence, can be used with any A. C. lighting current. It has an input of 750 volts and the high voltage secondary coil which energizes the plate has an output of 450 watts and develops 1,500 to 3,000 volts.
With Direct Current. When a 110 volt direct current is used to energize the power transformer an electrolytic interruptor is needed to make and break the primary circuit, just as a vibrator is needed for the same purpose with a spark coil.
This was a source of considerable encouragement to Marconi, and his apparatus was further improved so that the resonance of the circuit and the variation of the capacity of the primary circuit of the oscillation transformer made for increased efficiency.
To use the amplified radio frequency oscillating currents or amplified audio frequency alternating currents that are set up by an amplifier tube either a high resistance, called a grid leak, or an amplifying transformer, with or without an iron core, must be connected with the plate circuit of the first amplifier tube and the grid circuit of the next amplifier tube or detector tube, or with the wire point of a crystal detector.
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