Opamp circuit with -33KV

Discussion in 'General Electronics Chat' started by BrainInVat, Jul 21, 2012.

  1. BrainInVat

    Thread Starter New Member

    Jul 20, 2012
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    I am new to electronics and ltspice. I am trying to make an opamp integrator, but I am getting some very weird results. I am supplying the opamp with 12 V so I would not expect the output to be more than 12 V or less than -12 V, but my simulation gives an output between -32.8111 KV and -32.8101 KV. What am I doing wrong?

    Thanks
     
  2. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    Using a simulator to see what a circuit does that would take three minutes to build on a proto board.

    On the upside, at least the lie the computer told you was so far off you noticed it was wrong.
     
  3. BrainInVat

    Thread Starter New Member

    Jul 20, 2012
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    I don't have any actual parts yet, so building the circuit would take more than 3 minutes. Also starting small is a good way to learn. I would not be able to debug a more complicated circuit at this point.
     
  4. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    The simulation 'failed' because you didn't place a ground node on the Op Amp power supply.
     
  5. mlog

    Member

    Feb 11, 2012
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    What type of file is the "asc" file?
     
  6. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    It's a source file for LTSpice.
     
  7. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    I read in the first post:

    That takes an LM324, a ceramic cap, and maybe two resistors.

    Believe me when I tell you: buying a proto board and building things is the best way to learn.

    But, what do I know..... just one old man's opinion. I could very well be senile and would have no way to know for sure....?
     
  8. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    I assumed it meant "asci" type file. Whatever it is, it won't open.
     
  9. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    Which still makes me wonder how the sim thought that enabled it to create 33 KV from an op amp and 12V.....:D
     
  10. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    Perhaps it's a sign of electronic hypertension.
     
  11. crutschow

    Expert

    Mar 14, 2008
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    It should open if you have LTspice installed on your computer.
     
  12. crutschow

    Expert

    Mar 14, 2008
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    Also for that circuit you should have separate plus and minus supplies (connected to ground). That op amp is not designed to operate from a single supply.
     
  13. Papabravo

    Expert

    Feb 24, 2006
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    It is an ASCII text file describing the netlist of the circuit. What program are you trying to use to open it? If you are using a Windows machine you may have to get clever with "file associations" to open it as a text file.
     
  14. Audioguru

    New Member

    Dec 20, 2007
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    It is an ordinary LTspice file. It shows the opamp with a single (positive) supply and its (+) input is wrongly connected to 0V so it is not biased to work properly.

    The simulation is not set up correctly so it takes forever to finish (or never finishes) the simulation.
     
  15. BrainInVat

    Thread Starter New Member

    Jul 20, 2012
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    Thanks t_n_k. I got it to work. I have attached the ltspice circuit diagram.
     
  16. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    :) that explains it
     
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