Transistor Amplifier

Discussion in 'The Projects Forum' started by pchso, Mar 13, 2009.

  1. pchso

    Thread Starter New Member

    Mar 13, 2009
    4
    0
    How can I use a transistor to amplify a voltage from around 4V to 6V (not much)? I need the output from my 555 timer, which is around 4V, to run a 6V engine.
     
  2. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    The maximum allowed output current of a 555 is 200mA. Then its output voltage loss is about 2.0V to 2.5V.

    If the motor draws 200mA or less at 6V then the 555 can drive it. Increase the supply voltage of the 555 to 8.0V to 8.5V then its output voltage will be 6V.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Try this:
    [​IMG]

    R1 limits the current through the base of Q1.
    When the output of the 555 timer goes high, it causes Q1 to conduct; when the 555 output is low, Q1 turns off (stops conducting).
    D1 is there to take care of the motor's reverse EMF when Q1 breaks the circuit. It doesn't have to be a 1N4004; any rectifier diode should work fine.

    Q1 does need to be a 2N2222 or better; 2N3904 or 2N4401 won't likely have the current capacity needed.
     
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