power supply design

Discussion in 'General Electronics Chat' started by richbrune, Nov 6, 2005.

  1. richbrune

    Thread Starter Senior Member

    Oct 28, 2005
    106
    0
    Does anyone out there know how I might get the positive and negative supply voltage required to power a 741 or 1458 op amp from a transformer that is not center tapped? I am trying to amplify a small signal, but the signal goes from about zero to possibly as much as a volt, and sometimes it's not enough DC offset to get the amp to turn on at all, since the supply voltage to the op amp is zero and 12v DC positive. II need to power this circuit from a 24v RMS sine wave that goes positive and negative, but I'm only familiar with single supply (78xx) voltage regulators.
     
  2. Overclocked2300

    Senior Member

    Apr 24, 2005
    124
    0
  3. richbrune

    Thread Starter Senior Member

    Oct 28, 2005
    106
    0
    So your saying that if I erase the line shown going from the secondary centertap to between c1 and c2 this circuit will still work?
     
  4. mozikluv

    AAC Fanatic!

    Jan 22, 2004
    1,437
    1
    hi,

    this kind of power supply configuration will suffice if it will be used to power-up your 741 or 458.

    moz
     
  5. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    If you need a little bit more stable source than the first one, use this.
    And you can add some capacitors to the resistors and to the output, but they are not necessary.
     
  6. richbrune

    Thread Starter Senior Member

    Oct 28, 2005
    106
    0
    Thanks for this, kubeek--- if it works the way it seems it will, it's brilliant. It seems as though it puts a 1/2 vcc bias to a signal I might want to apply to subsequent op-amps, using that 1/2 vcc point as ground--- Am I correct? I'm eager to try this one.
     
  7. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,646
    759
    One caveat, though. If the op amp supply used is not able to deliver enough power you could get a misleading functioning.

    But for opamps (few of them) dealing with signal only, should be OK.
     
Loading...