Part of Made in India,Design Innovation

Workshop,2015

A  Fresh  New  Experience  in  

Project-­‐Making  and  Learning

PHYSICS INVESTIGATORY PROJECT ON

DARLINGTON PAIR

Do  you  know  how  a  high  current  gain  is  achieved  at  a  low  frequency  and  how  the  touch  and  light  sensors  work?  The  concept  of  Darlington  pair  will  make  you  understand  its  working.  In  a  touch  sensor,  there  are  two  electrodes  that  act  as  switches  and  when  they  are  open,  no  current  flows  through  the  circuit.  However,  if  you  put  your  fingers  across  the  two  electrodes,  your  body  closes  the  circuit.  Since  your  body  offers  a  very  high  resistance  to  the  circuit,  the  input  current  through  it  is  very  small.  We  install  a  Darlington  pair,  which  amplifies  this  current  twice  (usually  1,00,000  Rmes)  thereby  making  the  LED  glow  much  brighter.  

In  this  project,  a  Darlington  pair  circuit  is  made  using  two  transistors  (Q1  and  Q2),  two  resistors,  an  LED  and  a  few  connecRng  wires.  Q1  and  Q2  are  connected  in  such  a  way  that  the  current  amplified  by  Q1  is  further  amplified  by  Q2  i.e.,  the  collectors  of  both  the  transistors  are  connected  to  each  other  and  the  emiVer  of  Q1  is  connected  to  the  base  of  Q2.  It  was  observed  that  the  LED  glows  brighter  in  dual-­‐stage  amplificaRon  as  compared  to  single-­‐stage  amplificaRon.  Eventually,  base  current  and  collector  current  analysis  was  done  which  was  followed  by  the  verificaRon  of  the  amplificaRon  factor.

Have  a  look  at  our  Project  Kit!

CoolJunk   is   India's   fastest   growing  DIY   (do-­‐it-­‐yourself)   kits   company   focused   on   project-­‐based   learning   in  science,   engineering   and   technology.  Having   20,000   users   in   India,  US,   Singapore,   Middle   East   and   New  Zealand,  the  CoolJunk  kits  are  known   for  quality,  innovaRon   and  high  producRon  value.  CoolJunk  has  been  featured   in   naRonal   and   internaRonal   journals   including   Wallstreet,   Yourstory,   Hindu   Business   Line,  NextBigWhat  and  was  tagged  as  the  coolest  Indian  start-­‐up  in  IAN  Bootcamp-­‐2011.  

For  more  projects  visit  our  website:  CoolJunk  

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