Version 4
SHEET 1 880 680
WIRE 160 0 144 0
WIRE 272 0 160 0
WIRE 432 0 272 0
WIRE 144 16 144 0
WIRE 272 32 272 0
WIRE 432 96 432 0
WIRE 272 144 272 112
WIRE 320 144 272 144
WIRE 368 144 320 144
WIRE 272 208 272 144
WIRE 432 208 432 192
WIRE 592 208 432 208
WIRE 432 240 432 208
WIRE 224 304 144 304
WIRE 144 320 144 304
WIRE 272 320 272 288
WIRE 224 336 224 304
WIRE 432 336 432 320
WIRE 144 432 144 400
WIRE 224 432 224 384
WIRE 224 432 144 432
WIRE 272 432 272 400
WIRE 272 432 224 432
WIRE 432 432 432 400
WIRE 432 432 272 432
WIRE 560 432 560 320
WIRE 560 432 432 432
WIRE 144 448 144 432
FLAG 144 96 0
FLAG 160 0 vss
FLAG 144 448 0
FLAG 320 144 P1
FLAG 592 208 P2
SYMBOL voltage 144 0 R0
WINDOW 123 0 0 Left 2
WINDOW 39 24 112 Left 2
SYMATTR SpiceLine Rser=100m
SYMATTR InstName V1
SYMATTR Value {vss}
SYMBOL sw 272 416 M180
SYMATTR InstName S1
SYMATTR Value mfet
SYMBOL voltage 144 304 R0
WINDOW 3 -6 169 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value PULSE(0 1 10m 100n 100n 10m 20m)
SYMATTR InstName V2
SYMBOL res 256 16 R0
SYMATTR InstName R1
SYMATTR Value 10k
SYMBOL res 256 192 R0
SYMATTR InstName R2
SYMATTR Value 1k5
SYMBOL res 416 224 R0
SYMATTR InstName R5
SYMATTR Value 2K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL pnp 368 192 M180
SYMATTR InstName Q1
SYMATTR Value BC557C
SYMBOL res 544 224 R0
SYMATTR InstName R6
SYMATTR Value 100k
SYMBOL LED 416 336 R0
SYMATTR InstName D1
SYMATTR Value LA_T676-typ
SYMATTR Description Diode
SYMATTR Type diode
TEXT 136 488 Left 2 !.model mfet SW(Ron=50 Roff=10Meg Vt=0.5 Vh=-.3 Lser=10n)
TEXT 144 -104 Left 2 !.tran 0 50m 0 1u
TEXT 144 -88 Left 2 !.param vss=5
TEXT 144 -72 Left 2 !.step param vss list 3.3 5