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## Re: Creating a thermistor with a variable temperature

This is a Model created by my Software Prometheus developed in the past to supply Multisim/EWB with Simultation Models.NTC Level 1

The level 1 model of the NTC (Negative Temperature
Coefficient) is based on the basic NTC
equation which uses the B constant.

NTC Level 2
This model is based on the Steinhart-Hart equation
and can reproduce the nonlinear characteristics
better than the level 1 model. However it need more
simulation time.

Hope the two samples help.

* 0.1K1A1 ; NTC ; BetaTHERM ; BETA11
* Level 1 (von Wangenheim)
*
* Self heating
.SUBCKT BET_0.1K1A1 1 2
* | |
* TERMINALS: | B
* A
*
* PACKAGE: BETA11
* TEMPERATURE-RANGE: -55°C ... 100°C
*
V1 1 4 DC 0
R1 4 5 100
R2 8 0 500 RMOD
R3 9 0 7.38368E+05
R4 7 0 999.9999
R5 10 2 0.83932
B1 5 10 V=I(V1)*100*(EXP(3103.986/V(6)-3103.986/298.15)-1)
B2 0 7 I=ABS(V(1,10))*ABS(I(V1))
B3 6 0 V=(273.15+((V(8,0)/500)-1)*1000)+V(7)
C1 7 0 0.012
I1 0 8 1
.MODEL RMOD R(TC1=0.001 TNOM = 0)
*
* DATASHEET/DATABOOK: 1996-1997 Catalog
*
* VERSION: 2.0/1
* (C) Alexander Ehle/Stuttgart 08.04.99 09:54:21 Prometheus V2.0.0
*
.ENDS

* 0.1K1A1 ; NTC ; BetaTHERM ; BETA11
* Level 2 (Ehle)
*
* Self heating
.SUBCKT BET_0.1K1A1 1 2
* | |
* TERMINALS: | B
* A
*
* PACKAGE: BETA11
* TEMPERATURE-RANGE: -55°C ... 100°C
*
V1 1 4 DC 0
V2 9 0 DC 1
R1 4 20 1E+12
R2 8 0 500 RMOD
R3 19 0 7.38368E+05
R4 7 0 999.9999
R5 20 2 0.83932
C1 7 0 0.012
I1 0 8 1
B1 0 7 I=ABS(V(1,20))*ABS(I(V1))
B2 4 20 I=V(4,20)/(EXP(V(18)-V(17))+1E-12)
B3 6 0 V=(273.15+(((V(8,0)/500)-1)*1000))+V(7)
B4 10 0 V=(((1.942928E-03-(1/V(6)))/3.507238E-07)/2)
B5 11 0 V=(((1.942928E-03-(1/V(6)))/3.507238E-07)^2)/4
B6 12 0 V=V(9)*(((852.4542)^3)/27)
B7 13 0 V=ABS(V(11)+V(12))
B8 14 0 V=EXP(1/2*LN(ABS(V(13))))
B9 15 0 V=ABS(V(10)+V(14))
B10 16 0 V=ABS(V(10)-V(14))
B11 17 0 V=EXP(1/3*LN(ABS(V(15))))
B12 18 0 V=EXP(1/3*LN(ABS(V(16))))
.MODEL RMOD R(TC1=0.001 TNOM = 0)
*
* DATASHEET/DATABOOK: 1996-1997 Catalog
*
* VERSION: 2.0/1
* (C) Alexander Ehle/Stuttgart 08.04.99 09:54:21 Prometheus V2.0.0
*
.ENDS

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