* SPICE 3f5 (LTSpice/ngspice/macspice compatible) Switch + Switch Model demo
V1 A 0 5                                            $ supply voltage
S1 B 0 0 VC SW_MOD OFF                              $ voltage-controlled switch 
R1 B A 1K                                           $ load
V2 VC 0 DC 0 PULSE(0 2 0 .5m .5m 0 1m)              $ control voltage
.MODEL SW_MOD SW(Roff=1e6 Ron=500 Vt=-1.75 Vh=-.35) $ switch model
.tran 1u 1m
.plot v(A) v(B) v(VC) 
.end