Transistor as a switch for signal.

Discussion in 'General Electronics Chat' started by Manar Zaaboub, Aug 18, 2016.

  1. Manar Zaaboub

    Thread Starter New Member

    Aug 18, 2016
    1
    0
    Hi,
    lately I was hired to sit in a room with all of the electronic kit that I need to build whatever project I ever had in mind. For this reason I considered joining an online community for electronics, and I have chosen this forum because I already have been a member here a couple of years back, and I am glad that I am back again.
    The question is as this simple. How can a transistor be used as a switch, that is when closed can let a signal go through and when opened the signal is blocked ?. The signal is carrying information so when the switch is closed, the output (emitter) has to be exactly the same as the original signal, so that it can be parsed afterwards .

    I appreciate your help.
    Manar Zz
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,570
    2,380
    Do you want a switch or a linear analogue/amplifier?
    If the signal is digital, then the switch mode can be used.
    For a simple switch see 2n5551 BJT etc.
    Max.
     
  3. wayneh

    Expert

    Sep 9, 2010
    12,154
    3,061
    Are there monkeys with typewriters in the office next door?
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,056
    3,245
    For the most accurate analog switching you should use a MOSFET, which look like a low resistance when ON.
    A BJT has a small offset when ON that can slightly distort the signal.

    If you tells us the parameters of the signal you want to switch, we can give you a better answer.
     
  5. hp1729

    Well-Known Member

    Nov 23, 2015
    1,964
    219
    Design 812 a.PNG
    As crutschow suggested (simplified maybe).
     
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