lm318p not working??

Discussion in 'Homework Help' started by caoadon, Jul 11, 2014.

  1. caoadon

    Thread Starter New Member

    Jul 11, 2014
    24
    0
    Hi
    I've built an inverting set up with a lm318p op amp,
    but I can't seem to even get an inverting signal in general?
    I just want to get it working so right now the gain is only 1 (using two resistors of same value)

    Ive posted a picture

    [​IMG]
     
    Last edited by a moderator: Jul 11, 2014
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,504
    380
    hi,
    Please post a diagram of your circuit.
    E
     
  3. caoadon

    Thread Starter New Member

    Jul 11, 2014
    24
    0
    oh sorry. Here ya go
     
  4. caoadon

    Thread Starter New Member

    Jul 11, 2014
    24
    0
    sorry im new to this
    the supply voltage is +9V
    I connected the V- to GND

    [​IMG]
     
    Last edited by a moderator: Jul 11, 2014
  5. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,398
    497
    I see ground.

    I don't see power. You have red plug plugged into breadboard red socket. Normally from red socket you would run a wire to the breadboard. But you got nothing running from red socket to the breadboard.
     
  6. caoadon

    Thread Starter New Member

    Jul 11, 2014
    24
    0
    There's something there. its just a black wire
     
  7. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,504
    380
    hi,
    On some types of project board the power rails [ along the long edges ] are not linked thru at the centre pins.

    So if your gray wire is your scope 0V, it may not be connected!.

    Move your scope 0V lead to near the power input rail.
    E
     
  8. RichardO

    Well-Known Member

    May 4, 2013
    1,238
    385
    Don't forget to add power supply bypassing. The LM318 is very likely to oscillate without proper bypass.
     
  9. caoadon

    Thread Starter New Member

    Jul 11, 2014
    24
    0
    Tried that also. Didnt work! :(
    But thanks though
    Does it have to do with the parameters I have on the function generator?
    1kHz, 100mVpp 50mVos
     
  10. caoadon

    Thread Starter New Member

    Jul 11, 2014
    24
    0
    What is power supply bypassing?
     
  11. bertus

    Administrator

    Apr 5, 2008
    15,649
    2,348
  12. caoadon

    Thread Starter New Member

    Jul 11, 2014
    24
    0
  13. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,504
    380
    hi,
    A 100nF near the OPA and a 47uF on the project board power rails.
    E
     
  14. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,159
    I noticed the wire you have connected to pin 3 (Vcc-) is connected to your Vcc+ ... assuming that red wire is Vcc+

    The area around the posts is very unclear. Neaten up your diagram ....
     
    absf likes this.
  15. absf

    Senior Member

    Dec 29, 2010
    1,493
    372
    What program did you use to do the bread board layout?

    This is the strip board version of the same circuit.
     
Loading...