# Using the LTS .step Parameter

#### SamR

Joined Mar 19, 2019
4,122
Apparently I am not using it correctly... Thought I made an error in the .step but it is apparently having a problem with tl071?

#### ericgibbs

Joined Jan 29, 2010
15,342
hi Sam.
E

Update: the error is reporting a problem with the TL071, do you need an include.??

#### SamR

Joined Mar 19, 2019
4,122
It is definitely the TL071 model. Thought I had all of that resolved! You will get the same error unless you install the model.

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#### SamR

Joined Mar 19, 2019
4,122
Found the problem! .lib TL07xTI.txt was left off!

#### Papabravo

Joined Feb 24, 2006
18,086
The TL071 should tell LTspice where to find the subcircuit file.
The main choices are in the folder where the schematic is located, OR
in the library folder, probably located in your documents folder under ...\Documents\LTspiceXVII\lib

You can gains some insight about what your schematic is trying to do by going to the menu bar, and clicking on View | Spice Netlist

From the top line that begins "XU1..." you can see the symbol name is "TL071/TI" and down at the bottom you can see it is looking for a file called "TL071.mod" located in one of the folders in the library search path. It is most likely there is a reason why the subcircuit it is looking for cannot be found.

EDIT: Took too long to put the evidence together.

#### eetech00

Joined Jun 8, 2013
3,090

#### SamR

Joined Mar 19, 2019
4,122
Nope, no problem with the model. This is all on me as I forgot to include the .lib directive.

#### SamR

Joined Mar 19, 2019
4,122
In fact...

I did not cherry pick the 10k resistor or measure the 22uF cap and...

Good enuff for experimental results.

#### SamR

Joined Mar 19, 2019
4,122
But this does not calculate out to 10+Vpp...

LTS and the built circuit agree, but not the calculations.

#### Papabravo

Joined Feb 24, 2006
18,086
Your value for 2π is off by a bit. It should be 6.28319....
It looks like you slipped 2 decimal places on the capacitor.
$$22\mu\text{F}\;=\;22\times10^{-6}$$
and
$$X_C\;=\;(2\pi(100)22\times10^{-6})^{-1}\;=\;72.34$$