. An elementary manual of radiotelegraphy and radiotelephony for students and operators . diagram in Fig 6, is connected with three other resistances, so asto form a Wheatstones bridge arrangement. In the circuit ofthe battery B is placed a key k, and in the circuit of the galvano-meter is placed another key, y, and the galvanometer is joined in RADIOTELFCKAPIIIC StEASVREMEi\ TS 303 sories with a resistance, r, uiul also n coiideiiBer, C, is connecttnlbetween 0110 termimil of the ^iilvaiiouuter and oue un^^le of thebridge. Let K be llio rosislanco of the coil of wiiich the in-ductance is requi
. An elementary manual of radiotelegraphy and radiotelephony for students and operators . diagram in Fig 6, is connected with three other resistances, so asto form a Wheatstones bridge arrangement. In the circuit ofthe battery B is placed a key k, and in the circuit of the galvano-meter is placed another key, y, and the galvanometer is joined in RADIOTELFCKAPIIIC StEASVREMEi\ TS 303 sories with a resistance, r, uiul also n coiideiiBer, C, is connecttnlbetween 0110 termimil of the ^iilvaiiouuter and oue un^^le of thebridge. Let K be llio rosislanco of the coil of wiiich the in-ductance is required reckoned in ohms, and L iU* inductance inhenrys, and let TQS be the resistance of the other arms of thebridj^e. Tlun the lirst step in the process is to vary the valuesof P, Q and S, so that when the battery key is first put down, andafterwanls the galvanometer key. there is no movenjent of thegidvaui>meter coil or needle. The bridge is then said to ix»bidanced by steady currents. The resistance S should be a plug-box resistance runnin- from 0 to 10,000 or 20,000 ohms, and the. condenser C should preferably be a variable capacity. In obtain-ing a steady balance of the bridge, the resistance r should be cutout, and the condenser C removed. When the balance is obtainedthese instruments aie re-inserted, and we then find that if thegalvanometer key is first closed, and afterwards the battery key,the galvanometer coil or needle gives a throw or movement, which,however, can be entirely annulled by suitably varying the capacityC or the resistance r. When this is the case, the bridge is saidto be balanced for throws. The advantage of the Andersonmethoil is that in obtaining the balance for tlirows we do nothave to upset the steady balance previously obtained. When the 304 RADIOTELEGRAPHY steady balance is obtained, there is a proportionality between thefour resistances P, Q, E., S, expressed by the formula: ? = 5 Q S and when the balance for throws is obtained, there is a relat
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1916
