¿ªÔÆÌåÓý

  1. LTspice
  2. Topics

XVAR specification

 

Dear all,


I am designing a circuit in LTSPICE. I need a variable resistor to use it in my circuit. I try to use the variable resistor(XVAR) from LTSPICE library. After designing the circuit after using this variable resistor (XVAR) from LTspice library; I am unable to run the simulation. I am always getting this error-"Unknown sub-circuit called in xu8 n003 n008 50k". My variable resistance value is 50Kohm. Can anyone help me to solve this issue and let me know the following:

1.) What component has to be used for simulating variable resistor in the LTspice library?
2.) How to set the value of variable resistance for XVAR component?

Thanks & Regards,
M.Rakesh Sharma
 




---In ltspice@..., <rsrakeshbharath@...> wrote:

... I try to use the variable resistor(XVAR) from LTSPICE library.

What kind of resistor?
You used a varistor, is that you intended?
Look for the example
Schematic
in our group library.

hws
 

M.Rakesh Sharma?wrote:

I am designing a circuit in LTSPICE. I need a variable resistor to use it in my circuit. I try to use the variable resistor(XVAR) from LTSPICE library.

Are you trying to use a varistor (a resistor with a nonlinear resistance, its resistance depends on the voltage), or do you just need a potentiometer or rheostat? ?You might have mixed them up.

The "xvaristor" symbol in the library is for a varistor which is a nonlinear resistor. ?It requires a subcircuit (that you would provide), to describe its R(V) characteristics.

I think LTspice's built-in library has no component for a potentiometer, but there are several in this YahooGroup's "Files" section. ?Go to the "Table of Contents" area and download the file "all_files.htm". ?Then open it in your web browser, and search for "potentiometer". ?There are several to choose from.

Alternatively, you could just use an ordinary resistor symbol, and annotate it to show that it is a variable resistor or potentiometer. ?Its resistance value would be fixed during any one simulation, right?

Regards,
Andy
 

Dear Mr Andy,


Thanks for your suggestion. I chose one potentiometer from the all_files folder. But still I am unable to simulate my circuit if I use this component in my circuit. Same error message appears again - "Unknown sub-circuit called in: x001 n003 n008 nc_01 potentiometer rtot=50K wiper = 5"


Do it change anything after placing ths component in my circuit?


Thanks & Regards,

M.Rakesh sharma.
 

M.Rakesh sharma wrote, "
I chose one potentiometer from the all_files folder. But still I am unable to simulate my circuit if I use this component in my circuit. Same error message appears again - "Unknown sub-circuit called in: x001 n003 n008 nc_01 potentiometer rtot=50K wiper = 5"".

I haven't used the Potentiometer models so I can't say with certainty. ?But the one you picked is a subcircuit. ?(That might be true of all of them.) ?It is not only a symbol. ?You must also import or include the subcircuit definition. ?In the case above, it is looking for a subcircuit definition named "potentiometer", and it can't find it.

Check where you found the symbol and look for a subcircuit model that goes with it. ?The subcircuit model should begin with the line

.SUBCKT potentiometer ...

followed by other stuff. ?You can either call it with an .INCLUDE statement, or paste it directly into your schematic.

Regards,
Andy

1 - 5 of 5