741 non-inverting amp

Discussion in 'Homework Help' started by Bikermicefrommars, Apr 16, 2009.

  1. Bikermicefrommars

    Thread Starter New Member

    Apr 16, 2009
    2
    0
    Hey, i hope someone can help me.

    I've got to create a non-inverting amp from a 741. I've done the calc's and the research and am currently simulating it in a software package.

    I've got:

    +11v on the +v input
    -11v on the -v input

    a 50mV a.c sine wave prided on the + (non inverting) I/P and a feedback loop to the - (inverting) I/P

    In essence this circuit is to convert the 50mv sine wave I/P into a 8V sine wave O/P but currently does not work.

    After attaching a 'scope to the O/P and to the 50mV I/P, the 'scope shows that the sine wave is being produced correctly but the O/P of the 741 is = to +V supply.

    PLEASE ADVISE!!!!
     
    Last edited: Apr 16, 2009
  2. bertus

    Administrator

    Apr 5, 2008
    15,648
    2,347
    Hello,

    Can you upload a schematic of your setup?
    PNG is the best format for uploading pictures.

    Greetings,
    Bertus
     
  3. Bikermicefrommars

    Thread Starter New Member

    Apr 16, 2009
    2
    0
    CCT attached,

    please help!
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You have 11v (V1) on Vcc (pin 7), but Vee (pin 4) tied to GND.
    If you connect -11v to Vee, it should work. You'll need to add a V2 supply to get -11v. Add another 11v battery; it'll be named V2. lConnect V2's + output to GND, and it's - output to Vee (pin 4).

    If for some reason you need to keep it as a single-supply schematic, you'll need to use a couple of voltage dividers.
    XFG1 will need it's GND lead connected to the wiper of a pot (VR1) that has it's ends connected across 11v and ground. Set it exactly at midpoint to start. R1 will need to increase to 2k, and another 2k resistor added from the junction of RF and R1 to 11v.

    If it's wired as a single-supply, your output will be an AC signal riding at some DC level above 0v; if VR1 is set incorrectly, your output's waveform will be "clipped". Adjust VR1 to adjust the output offset.
     
    Last edited: Apr 16, 2009
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