﻿486 
  

  

  Mr. 
  B. 
  S. 
  Cohen 
  on 
  Production 
  of 
  Small 
  

  

  At 
  300 
  ohms 
  the 
  oscillation 
  begins 
  to 
  appear 
  during 
  the 
  

   current 
  rise 
  on 
  the 
  make 
  contact, 
  whilst 
  at 
  100 
  ohms 
  the 
  

   oscillation 
  is 
  entirely 
  confined 
  to 
  the 
  rise 
  during 
  the 
  make 
  

   contact. 
  

  

  The 
  resistance 
  is 
  still 
  large 
  enough 
  to 
  cause 
  the 
  current 
  to 
  

   rise 
  very 
  quickly 
  to 
  its 
  maximum 
  value, 
  thus 
  giving 
  a 
  nearly 
  

   square 
  shouldered 
  wave. 
  

  

  As 
  the 
  resistance 
  is 
  still 
  further 
  reduced 
  the 
  current 
  takes 
  

   longer 
  to 
  rise 
  to 
  its 
  maximum 
  value 
  and 
  at 
  the 
  same 
  time 
  

   the 
  oscillation 
  is 
  reduced, 
  until 
  ultimately 
  at 
  ohms 
  the 
  

   familiar 
  current 
  rise 
  curve 
  with 
  no 
  superimposed 
  oscillation 
  

   is 
  produced. 
  

  

  In 
  the 
  double 
  action 
  circuit 
  as 
  illustrated 
  (fig. 
  8) 
  a 
  

   capacity 
  shunted 
  by 
  an 
  inductance 
  is 
  introduced 
  in 
  place 
  of 
  

   the 
  simple 
  resistance. 
  This 
  somewhat 
  modifies 
  the 
  action 
  

   of 
  the 
  circuit. 
  If 
  the 
  inductance 
  L 
  2 
  is 
  inserted 
  as 
  shown 
  in 
  

   the 
  figure 
  and 
  the 
  capacity 
  K 
  2 
  omitted, 
  the 
  effect 
  is 
  to 
  give 
  

   an 
  oscillation 
  on 
  the 
  make 
  contact, 
  the 
  frequency 
  of 
  which 
  

   is 
  determined 
  by 
  the 
  combined 
  inductance 
  of 
  L 
  x 
  and 
  L 
  2 
  and 
  

   the 
  capacity 
  K 
  : 
  . 
  When 
  the 
  capacity 
  K 
  2 
  is 
  added 
  a 
  similar 
  

   effect 
  is 
  produced. 
  The 
  resulting 
  make 
  frequency 
  being- 
  

   due 
  to 
  the 
  combined 
  effect 
  of 
  both 
  inductances 
  and 
  capacities. 
  

   The 
  break 
  oscillation 
  will 
  be 
  that 
  due 
  to 
  L, 
  and 
  K 
  t 
  only. 
  

  

  Fig. 
  10 
  (PL 
  XVIII.) 
  shows 
  two 
  waves 
  produced 
  by 
  this 
  

   circuit. 
  The 
  following 
  small 
  table 
  gives 
  the 
  necessary 
  data: 
  — 
  

  

  Wave. 
  

  

  Values 
  of 
  

  

  Frequency 
  of 
  oscillation 
  : 
  

  

  Lj 
  henrys. 
  

  

  1m 
  henrys. 
  

  

  Ki 
  mfds. 
  

  

  K 
  2 
  mfds. 
  

  

  make 
  contact. 
  

  

  break 
  contact. 
  

  

  a 
  ! 
  -037 
  

  

  b 
  ! 
  -037 
  

  

  1 
  

  

  •037 
  

   -037 
  

  

  1-67 
  

   •167 
  

  

  '167 
  

   1-67 
  

  

  1020— 
  

   1020— 
  

  

  715— 
  

   2160— 
  

  

  Double 
  Action 
  Circuit 
  with 
  two 
  Transformers. 
  — 
  By 
  inserting 
  

   a 
  second 
  transformer 
  in 
  circuit 
  as 
  shown 
  in 
  fig. 
  11, 
  two 
  

   separate 
  and 
  distinct 
  oscillations 
  can 
  be 
  obtained. 
  If 
  the 
  

   circuits 
  are 
  similar 
  two 
  separate 
  waves 
  will 
  be 
  produced 
  the 
  

   shape 
  of 
  which 
  will 
  be 
  exactly 
  similar. 
  

  

  By 
  joining 
  up 
  the 
  two 
  secondaries 
  so 
  that 
  these 
  two 
  waves 
  

   either 
  assist 
  or 
  oppose 
  each 
  other, 
  some 
  interesting 
  results 
  

   are 
  obtained. 
  

  

  Fig. 
  12 
  (PI. 
  XVIII.) 
  shows 
  two 
  900 
  - 
  break 
  oscillations 
  

   assisting 
  one 
  another. 
  The 
  make 
  oscillations 
  oppose 
  each 
  other 
  

   and 
  are 
  therefore 
  wiped 
  out, 
  the 
  result 
  being 
  to 
  give 
  a 
  wave 
  

  

  