Help needed on op amp

Discussion in 'The Projects Forum' started by Larryboyz, Jun 5, 2012.

  1. Larryboyz

    Thread Starter New Member

    May 31, 2012
    12
    0
    Hi there, im now facing one problem which i need to doubling my output voltage to 10vDC -15vDC. As we know, the voltage from microcontroller only 5vDC. Is there any circuit or component i can use to doubled my output voltage. I have try one circuit which i will upload later. When simulate in multisim, everything seem function but when i transfer it to real circuit, it didnt function as expected more worst the output voltage decrease to half of the input. Anyone can help me?

    Op-amp- http://db.tt/1sYtVNjq
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,431
    3,360
    Is this DC output or AC?
    You can increase the voltage of AC signal using a transformer or a diode-capacitor voltage doubler.
    To get 15v DC from your MCU you will need a 15V power source. You can boost 5vDC to 15vDC using a DC-DC converter.
     
  3. mcasale

    Member

    Jul 18, 2011
    210
    12
    The link you have shows a 2-stage, unity gain amplifier. What are you trying to do? What is your negative supply on the 741 op amps?
     
  4. crutschow

    Expert

    Mar 14, 2008
    12,995
    3,229
    The circuit you show has a 10V positive power supply (where is that coming from?) and nothing connected to the negative op amp terminal. Even if you ground the negative terminal you will get only about 7-8V output maximum from the 741. Obviously that's not going to work for you.

    You need a circuit to boost the voltage such as a boost switching regulator. If the required current is small you might be able to use a switching capacitor type voltage tripler circuit.
     
  5. Larryboyz

    Thread Starter New Member

    May 31, 2012
    12
    0
    This is DC input and output. I need to have 15vDC in order to make my IGBT function. But, microcontroller only supply 0-5vDC. I need a circuit that able to doubled my output voltage. For the circuit i post, I got the circuit from some forum and simulate it inside the multisim. It work. But when i transfer to real board, the output voltage decrease by half of the input. Anyone have any circuit diagram or example.
     
  6. StayatHomeElectronics

    Well-Known Member

    Sep 25, 2008
    864
    40
    It looks like your simulation showed you doubling a 3.3v input to 6.6v. I think everyone would agree that the circuit is capable of doing that with a 10v supply, as you simulated.

    With a 5v supply, you will not get much beyond 3-3.5v with the 741.

    Reread all of the other posts. You have been given some good suggestions already as well as having been asked some questions that would help those trying to help you.
     
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