Show CRYSTAL JARRING CAN BE PREVENTED 1 simple shock absorber that was devised by operator on a transoceanic vessel one of tile the worst irritations buffered ly lly the crystal detector operator is thet the tre re quent jarring out of good adjust abent often the all slightest blest vibration caused by a henry heavy footfall slamming of a door or someone brushing against tile the table a sufficient clent to disturb tile the good point the process of the readjustment Just merit has to be gone through again this happens with such re regularity that numerous schemes to avoil jarring the detector stand have heart ben devised most of these were failures and the P phrase araso dont jar out Lc be RV bubber liber bands L tame lame a standard joke there Is one scheme which hlll III protect the adjust nent from almost anything short of an earthquake this idea was first encountered on it i shipping bourd board vessel ylie the vibration ia a ship is great and for this reason ulena cannot ordinarily be kept in id and Is rarely used how flow iveron on a in service he crystal costal co stal i cless the very best dosal ole dle will rill not bring in a signal for days it a time when tile the ship Is neur mid ij eean cean far any lund land staff stations tills peral per r had bad rigged up a shock miloc absorb tr r for his ablena detector us as shown n the figure little explanation Is nee A block of wood a foot square r smaller supports four our large nails or wood posts between which are stretched rubber bands as shown these sands support the detector stand if the stand Is heavy with a small base it ft will be top heavy and the stand had better be mounted on a larger base the rubbers should bs be only heavy enough to keep the stand from touching the block so that there Is plenty of flexibility to absorb all vibration use a flexible cord for connecting the detector into the circuit so that it can be taken oft off the shock absorber and adjusted on the table when a 0 chod adjustment Is obtained carefully deplace the lie detector on the shock absorber and it will stay in adjustment almost indefinitely unless of course disturbed by the heavy signals or static italic in the case mentioned the def detector dete cor eeor would hold an adjustment through an entire watch though the vibration from the engine was pronounced and in a heavy sell sea there were strong tremors and jumps this ship rolled but although the detector 03 L 1 z almost blood ion in end during the bad rolls unless the adjustment was particularly erratic no trouble was had it will repay anyone who lias has had trouble with keeping beeping a good adjustment to construct tills this simple jur jar absorber the detector Is used to rectify alternating terna ting current of radio frequency oscillations Osel lations of radio frequency are inaudible the mr ear being able to dig only up to a frequency of per second at the alie very highest the longest radio frequency waves are about meters wave length or oscillations per second which Is well above audibility and also above tile frequency rungs range of the telephone diaphragm the frequency of the present short hort wave length la it sany times as high as a tills this the frequencies clos that we hear bear are upon the currier carrier wave in variations la in of the carrier waves wave if only a tuning device and phones were ivere used at tile the receiving station without some kind of rectifier rec tiller title wave modulated by tile audible frequencies quen cies cles have no coteil what tifer saver on the of tile the headset because regardless reg ardless of the streng strength tit of lilt oscilla oscillations tiona or tile per ieni of modulation the positive haf la is always and opposite to 10 tile negative tive half balf und and they will wil exactly neutral ize each other when rec titled elthel either terl uie positive 0 rive or the side of thu the currier r auve la is cut off leaving tile luer hulf free to afflict tile ne fie counteraction ot of tue ui appe site it bull of the wave the more perfect the rectification the louder the signal will be in ID the phones because tile resultant audible current Is the difference between the two two halves of tile the cycle tile crystal in ig not a perfect rectifier it Is merely a resistance which does not follow ohms law it offers wore more resistance si to a current lowing la in one direction than tile the other suppose tile positive half hair of tile the current Is to be utilized part partially killy neutralize neut ralise the positive tive current reducing the strength of 0 the signal A curve for a ealen gale in crystal Is shown us its curve no 1 in fig 1 the curve will vary for aery nd adjustment rin on the crystal this graph represents represent a very good eod adjustment tile the best signal no will be obtained when the sharp pat cst bend in the curve Is at the working point in the file case of the golena galena crystal this point would be at etro potential at tills this point the rectification will be the highest some require a local battery and potentiometer to bring the lie vl working point to the proper point on oll the curve cuite curve no 2 Is ig tor for a borun dum crystal to work tins this cry crystal 6 to hobt effectively the potentiometer er would have to be adjusted to give elve a positive potential of about three volta the dotted line for no 3 Is for an ordinary and Is a strul glit line |