Transistor Amplifier

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

  1. pchso

    Thread Starter New Member

    Mar 13, 2009
    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


    Dec 20, 2007
    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


    Jul 17, 2007
    Try this:

    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.