Opinion about Design LTSPICE

Discussion in 'Programmer's Corner' started by Kierip Sab, Mar 11, 2016.

  1. Kierip Sab

    Thread Starter New Member

    Mar 11, 2016
    7
    0
    Dear Tinkerers, Electronic Engineers,

    I was wondering if I could get an second opinion about the follow circuit.
    It has the functionality to be driven by a 1.5V source/beaglebone black.
    amplifies it to 3.0V then level shifts it. to 1.5 ... -1.5V.
    I am using the LT1354 for the whole circuits because of the slew rate of the Square wave.
    the filter is set on 1KHz
    noise ratio looks nice,
    FFT is below -20dB:D good enough for starters.

    So what can I do to optimize the circuit?
    I placed caps where they are needed.
    I tried changing the Offset and the amplification, Tried to remove R7 which is required elsewise it will start to oscillate.
    kind of tried the In put output matching, but R3 has to be a potentiometer, and R13 and R5 as well.

    what can I do to optimize it even more?
    I am so excited:D

    sincerely yours

    Bastiaan Pierik
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    So what is the circuit supposed to do?
    Post your .asc file.
     
  3. Kierip Sab

    Thread Starter New Member

    Mar 11, 2016
    7
    0
    Ill upload it as an zip
     
  4. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    Just upload the .asc file directly.
    You didn't answer my question.
     
  5. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,777
    931
    No one with any common sense will download a ZIP file to their computer when it comes from an unknown poster who only has one single post.
    Upload the file itself, so the .extension is visible and people will open it and try to help you
     
  6. Kierip Sab

    Thread Starter New Member

    Mar 11, 2016
    7
    0

    :S ok, Ill explain... the All About Circuits doesnt allow me to post the ASC file.
    please check for yourself. The only way to upload it was to Zip it. and 7zip didnt work either thats why I had to shift to a standard ZIP file. I hope this explains enough to go around your paranoia. and get a decent Virus Scanner, Registry cleaner or whatsoever if you dont thrust me. I am not the IS, but I am the Devil incarnate and I would like to take over the world and infect you all. My other name is Evermore99 for somehow this website didnt allow me to log me in twice and I have same as your paranoia, to much passwords.

    Good Morning and have a nice day!
     
  7. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    Below is a random .asc file I just uploaded using the "Upload a File" button at the bottom of the post.
    It's not that I don't trust you, I just don't like the extra pain of messing with ZIP files.
     
  8. Kierip Sab

    Thread Starter New Member

    Mar 11, 2016
    7
    0
    sometimes I have a temper in the morning:),
    funny just dragging in the box works but using the Upload file has a limit what you can upload:p I am getting old...
     
  9. ScottWang

    Moderator

    Aug 23, 2012
    4,853
    767
    Welcome to AAC.
    Please be polite to the helpers, they spent their free time to help you with no pay.
    You just came here to asked for help, and many things you don't know, as crutschow described is quite common here, if you want to get help, please follow what the helper said and you also need to post a gif or jpg file as 800x600 for your circuit, some helpers may not install the LTspice, but they still can help you, and that is very common to attach the images could let every members can see as jpg or gif.
     
    Kierip Sab likes this.
  10. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,776
    1,103
    Ok, so now we've got the asc file. But, as crutschow asked, exactly what is your circuit supposed to do? You seem to be trying to filter out >1kHz components from a 50Hz square-wave input? How would you define 'optimum' in this context?
     
  11. Kierip Sab

    Thread Starter New Member

    Mar 11, 2016
    7
    0

    I know I know, I did misbehave.
    ok I did post a schematic.
    there were some problems with the uploading.
     
  12. Kierip Sab

    Thread Starter New Member

    Mar 11, 2016
    7
    0
    wel
    Ill enlighten.
    I would like to heat up Peltiers and control it by a feedbackloop
    I would like to drive from an DAC a 0 till 1.5V signal then amplify it, level shift it filter it and then in a max8521 to 1.5 till -1.5V max.
    there are a lot of spikes on the square wave pulse, which are of higher frequencies (I believe it was something with the impulse response and Dirac function).
    based on the step response of the max8521 I placed the filter on 1ms/ 1KHz.

    what I was looking for was advice, because I have never build a circuit like this before.
    things I know are:
    Filtering on the VCC and VSS are 0.1uF Tantalum + 1uF or MLCC's.
    guardrings around the +- of the opamps.
    what I dont know is how to optimize this circuit for longterm stability, Low drift and less Calibration.
    are there more recommendations how to inprove the circuit, based on Noise and FFT?
    I tried placing the filter, and level shifter in various positions
    the Flank of a squarewave pulse how steep should it be, because of the opamp slewrate?
    which other opamps are adequate or better than the LT1354?

    sincerely yours
    and thank you for your time.
     
Loading...