+ Post New Thread
Results 1 to 6 of 6
  1. #1
    Newbie level 3
    Points: 27, Level: 1

    Join Date
    Oct 2019
    Posts
    3
    Helped
    0 / 0
    Points
    27
    Level
    1

    Zener diode simulation problem using multisim 12.0

    Hello,
    I am new to multisim and just started learning how to simulate basic circuits. I am using multisim 12.0.

    I am trying to simulate a basic zener diode circuit and trying to observe the effect of changing the load resistance.
    I believe this needs to be done using parameter sweep.
    The problem I am facing is, in the parameter sweep window, I am not seeing my load resistor name in the drop down list of the component name I want to sweep. I am seeing r1:xrload, r1:xr1. r1:xr2, r2:xrload etc. At the same time, I am seeing that the present value of r1:xrload and r2:xrload is set to 5k. My load resistor value has been set to 10k in the schematic. Another peculiar thing is, I don't have any r2 resistor in my circuit. Could anyone kindly help me out regarding this? My questions are:

    1) What are these r1:xrload, r1:xr1. r1:xr2, r2:xrload etc.
    2) How is my rload value getting halved?
    3) I have also looked at the netlist as well, and it shows 10000/2 there as well. Could anyone please tell me why?

    I will really appreciate some help in understanding what's going on here. Thank you.

    P.S. I have looked at the multisim forum and I couldn't find a relevant problem. The youtube tutorials also don't have such weird names in the name field.

    I am attaching the screenshot herewith.

    Additional circuit info:
    Components used: DC_Power for voltage source, resistor_rated for r1 and rload, zener (virtual) for the zener diode.Attachment 156035
    Last edited by KlausST; 14th October 2019 at 20:32. Reason: Disabled smilies

    •   AltAdvertisement

        
       

  2. #2
    Advanced Member level 5
    Points: 53,741, Level: 56
    Achievements:
    7 years registered
    Audioguru's Avatar
    Join Date
    Jan 2008
    Location
    Toronto area of Canada
    Posts
    8,753
    Helped
    2053 / 2053
    Points
    53,741
    Level
    56

    Re: Zener diode simulation problem using multisim 12.0

    Your attachment cannot be seen because it is invalid.



    •   AltAdvertisement

        
       

  3. #3
    Newbie level 3
    Points: 27, Level: 1

    Join Date
    Oct 2019
    Posts
    3
    Helped
    0 / 0
    Points
    27
    Level
    1

    Re: Zener diode simulation problem using multisim 12.0

    Click image for larger version. 

Name:	param.png 
Views:	4 
Size:	49.1 KB 
ID:	156043Click image for larger version. 

Name:	param.png 
Views:	4 
Size:	49.1 KB 
ID:	156043

    https://imgur.com/gallery/sRXpvzg

    Sorry, please let me know if this works.



    •   AltAdvertisement

        
       

  4. #4
    Super Moderator
    Points: 53,074, Level: 56

    Join Date
    Apr 2011
    Location
    Minneapolis, Minnesota, USA
    Posts
    12,979
    Helped
    2583 / 2583
    Points
    53,074
    Level
    56

    Re: Zener diode simulation problem using multisim 12.0

    Did you try a similar circuit from the examples folder?

    Did the same problem appear with simpler circuits? Say, a resistor and voltage source?

    Once you get a simple circuit to work, then add components.



  5. #5
    Newbie level 3
    Points: 27, Level: 1

    Join Date
    Oct 2019
    Posts
    3
    Helped
    0 / 0
    Points
    27
    Level
    1

    Re: Zener diode simulation problem using multisim 12.0

    Yes, tried and failed. Same thing appears. I have scoured the multisim forum. From what I could find is that this expression should appear for the pots (with the wiper dividing the 2 resistors in the pots) which is weird as I have used the RESISTOR_RATED component and not the pot.
    I have tried just a simple voltage source and a resistor. I am attaching the screenshot herewith.

    Notice that r2 is appearing even though I have called only 1 resistor.
    I should mention this that DC and transient analysis works perfectly.

    https://imgur.com/gallery/RkgXdD6
    Click image for larger version. 

Name:	1.png 
Views:	3 
Size:	23.0 KB 
ID:	156046



    •   AltAdvertisement

        
       

  6. #6
    Advanced Member level 5
    Points: 53,741, Level: 56
    Achievements:
    7 years registered
    Audioguru's Avatar
    Join Date
    Jan 2008
    Location
    Toronto area of Canada
    Posts
    8,753
    Helped
    2053 / 2053
    Points
    53,741
    Level
    56

    Re: Zener diode simulation problem using multisim 12.0

    I do not know what you are trying to do.
    1) You have a 5V Zener diode with no part number and no spec's. Nobody makes one but 5.1V is common so my calculations use 5.1V.
    2) You are simulating sweeping the load resistance. Why?

    I do not know if Multisim has a library full of Zener diode datasheets. A 1N5231B Zener diode is 5.1V only when its current is 20mA. At less current then its voltage is less. Around 0.25mA its voltage regulation is very poor.
    You have a 16V supply and a 10k load. The load current is 5.1V/10k= 0.51mA. The current in the 470 ohm resistor is (16V-5.1V)/470 ohms= 23.2mA. Then the current in the Zener diode is 23.2mA - 0.51mA= 22.7mA so the voltage will be very close to the rated +-5% which is for a current of 20mA.

    For such a low load current of only 0.5mA then I would use a Zener diode that is rated at a current less than 20mA like 5mA. A 1N5993B is 5.1V rated at 5mA then the resistor feeding it can be (16V - 5.1V)/5.5mA= 1982 ohms, use 2k ohms.



--[[ ]]--