Does anyone have a SPICE model for a Silicon Unilateral Switch (SUS) e.g. 2N4990, 2N4987, or NTE6404.

I am building a circuit in Multisim and need the component.
Thanks,
Blizz

 

I don't have one of a SUS, but here's some stuff that might help you:

Here's a couple of models for PUTs.
1: Anode
2: Gate
3: Cathode

*Default Programable Unijunction Transistor pkg: TO-92
.SUBCKT PUT 1 2 3
Q1 2 4 3 NMOD
Q2 4 2 1 PMOD
.MODEL NMOD NPN()
.MODEL PMOD PNP()
.ENDS XPUT

*Programable Unijunction Transistor pkg: TO-226AA
.SUBCKT 2N6027 1 2 3
Q1 2 4 3 NMOD
Q2 4 2 1 PMOD
.MODEL NMOD NPN(IS=5E-15 VAF=100 IKF=0.005 ISE=1.85E-12 NE=1.45 
+ RB=10 RE=0.5 RC=0.5 CJE=3.5E-11 VJE=0.75 CJC=1.1E-11 VJC=0.75 TR=4.76E-8 
+ TF=16N VJS=0.75 )
.MODEL PMOD PNP(IS=2E-15 VAF=100 IKF=0.005 ISE=1.9E-12 RB=10 RE=0.5 
+ RC=0.5 CJE=3.5E-11 VJE=0.75 TF=1.6E-8 CJC=1.1E-11 VJC=0.75 TR=5.1E-8 
+ TF=16N VJS=0.75 )
.ENDS 2N6027

And for 7.5v & 8.2v 500mW Zeners:

.MODEL 1N755 D(IS=1E-11 RS=3.359 N=1.27 TT=5E-8 CJO=2.959E-10 VJ=0.75 M=0.33 BV=7.433 IBV=0.01 Vpk=7.5)
.MODEL 1N756 D(IS=1E-11 RS=3.858 N=1.27 TT=5E-8 CJO=2.749E-10 VJ=0.75 M=0.33 BV=8.123 IBV=0.01)

That should be enough to at least get you started.

If you want to try to first build one schematically, have a look in our Thyristor section:
http://www.allaboutcircuits.com/vol_3/chpt_7/8.html

The 2N6027 is discussed near the bottom of the page.

 

Thank you Sgt Wookie
Blizz