# Measuring NTC behaviour on LTSpice

#### kalemaxon89

Joined Oct 12, 2022
231
I continue here what I started at the end of this other thread.

I am watching this video and would like to simulate the circuit at 12:52 minutes.
The problem is as follows:

As @ericgibbs has already said... checking my circuit, it appears that I am trying to determine the resistance of R1 using the values in the T_NTC equation which depend on the values of R1, which in turn depend on the values of T_NTC.
(i.e.: two interdependent unknown values)

If you keep watching the video, the graphic that will come out will be this:

V(t_ntc) represents temperature! not voltage!

There is something in the simulation shown in the video that you cannot see at 12:52 minutes that allows you to simulate without errors ... but what?

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#### ericgibbs

Joined Jan 29, 2010
18,641
hi k,
Watched the video, created the circuit for simulation, got the same error as you.

Perhaps @Bordodynov will have an answer.

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#### kalemaxon89

Joined Oct 12, 2022
231
hi k,
Watched the video, created the circuit for simulation, got the same error as you.

Perhaps @Bordodynov will have an answer.

E
Thank you very much!
1) Can you explain why you wrote ic={TEMP} in the capacitor? What does it mean? Does it change anything if I remove it?
2) What is 'Amme' and how did you palce it (the arrow in the circuit branch)?

#### Papabravo

Joined Feb 24, 2006
20,992
Thank you very much!
1) Can you explain why you wrote ic={TEMP} in the capacitor? What does it mean? Does it change anything if I remove it?
2) What is 'Amme' and how did you palce it (the arrow in the circuit branch)?
The .ic command sets an initial condition on a component.
The Amme is a custom symbol that is a voltage source set at 0 V DC which will allow you to use the current going through it in an expression.

#### Bordodynov

Joined May 20, 2015
3,165
Amme is an abbreviation for Ammeter, a current meter. I was too lazy to write the full name. I thought four letters would be enough to understand the function.

#### ericgibbs

Joined Jan 29, 2010
18,641
hi k89,
Press F2 for this pop up, to select the Ammeter.

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