Version 4
SHEET 1 888 680
WIRE -16 -224 -32 -224
WIRE -32 -176 -32 -224
WIRE 528 -176 368 -176
WIRE 560 -144 560 -160
WIRE 560 -144 512 -144
WIRE 720 -144 560 -144
WIRE 64 -128 64 -144
WIRE 368 -128 368 -176
WIRE 560 -112 560 -144
WIRE 720 -112 720 -144
WIRE 464 -32 464 -96
WIRE 240 -16 192 -16
WIRE 368 -16 368 -48
WIRE 368 -16 320 -16
WIRE 432 -16 368 -16
WIRE 528 -16 528 -176
WIRE 560 -16 560 -32
WIRE 560 -16 528 -16
WIRE 720 -16 720 -48
WIRE -32 0 -32 -96
WIRE 0 0 -32 0
WIRE 64 0 64 -48
WIRE 512 0 512 -144
WIRE 512 0 496 0
WIRE 560 0 560 -16
WIRE 432 16 400 16
WIRE 0 32 0 0
WIRE 400 32 400 16
WIRE 560 80 560 64
WIRE -32 96 -32 0
WIRE 64 96 64 80
WIRE 64 96 -32 96
WIRE 464 96 464 32
WIRE 400 144 400 112
WIRE 720 144 720 64
WIRE 720 144 608 144
WIRE -32 160 -32 96
WIRE 720 192 720 144
WIRE -32 272 -32 240
WIRE 0 272 -32 272
WIRE 560 288 560 176
WIRE 640 288 560 288
WIRE 720 288 720 256
WIRE 720 288 640 288
WIRE 640 336 640 288
FLAG 400 144 0
FLAG 560 -160 Sen
IOPIN 560 -160 Out
FLAG 464 96 V-
IOPIN 464 96 In
FLAG 464 -96 V+
IOPIN 464 -96 In
FLAG 640 336 0
FLAG 64 -144 Tri
IOPIN 64 -144 Out
FLAG 0 272 V-
IOPIN 0 272 Out
FLAG 0 32 0
FLAG -16 -224 V+
IOPIN -16 -224 Out
FLAG 192 -16 Tri
IOPIN 192 -16 In
SYMBOL res 384 16 R0
WINDOW 0 -33 31 Left 0
WINDOW 3 -52 63 Left 0
SYMATTR InstName R6
SYMATTR Value 120k
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res 336 -32 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R7
SYMATTR Value 22k
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL Robertugo\\OPAMP5 464 -64 R0
WINDOW 0 -24 62 Left 0
WINDOW 38 -71 17 Left 0
SYMATTR InstName U1
SYMATTR SpiceModel level2
SYMBOL res 352 -144 R0
WINDOW 0 -37 34 Left 0
WINDOW 3 -38 63 Left 0
SYMATTR InstName R8
SYMATTR Value 10k
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL njf 608 80 M0
WINDOW 0 57 22 Left 0
WINDOW 3 23 49 Left 0
SYMATTR InstName J1
SYMATTR Value BF245A
SYMBOL res 544 -128 R0
WINDOW 0 25 47 Left 0
WINDOW 3 25 89 Left 0
SYMATTR InstName R11
SYMATTR Value 180k
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL cap 704 192 R0
WINDOW 0 -20 10 Left 0
WINDOW 3 -24 57 Left 0
SYMATTR InstName C1
SYMATTR Value 1n
SYMATTR SpiceLine V=16 Irms=0 Rser=0.007 MTBF=0 Lser=0 mfg="TDK" pn="C3216X7RIC105K" type="X7R" ppPkg=1
SYMBOL diode 736 -48 R180
WINDOW 0 79 54 Left 0
WINDOW 3 40 30 Left 0
SYMATTR InstName D1
SYMATTR Value 1N914
SYMBOL res 704 -32 R0
WINDOW 0 -62 35 Left 0
WINDOW 3 -62 64 Left 0
SYMATTR InstName R13
SYMATTR Value 10K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL voltage -32 -192 R0
WINDOW 0 -42 3 Left 0
WINDOW 3 -16 57 Left 0
WINDOW 123 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 7.5
SYMATTR SpiceLine Rser=.25 Cpar=50n
SYMBOL voltage -32 256 M180
WINDOW 0 -39 112 Left 0
WINDOW 3 -16 57 Left 0
WINDOW 123 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value -7.5
SYMATTR SpiceLine Rser=.1 Cpar=50n
SYMBOL voltage 64 -144 R0
WINDOW 0 -15 60 Left 0
WINDOW 3 -16 57 Invisible 0
WINDOW 123 0 0 Left 0
WINDOW 39 4 134 Left 0
SYMATTR InstName V3
SYMATTR Value PULSE(0 {Vt} 0 1u 1u 0 2u)
SYMBOL voltage 64 96 R180
WINDOW 0 17 16 Left 0
WINDOW 3 -28 55 Left 0
WINDOW 123 0 0 Left 0
WINDOW 39 -35 215 VRight 0
SYMATTR InstName V4
SYMATTR Value {Vt/2}
SYMATTR SpiceLine Rser=1
SYMBOL cap 544 0 R0
SYMATTR InstName C2
SYMATTR Value 1n
TEXT 192 240 Left 0 !.tran 0 10m 9440u
TEXT 184 272 Left 0 !.step param Vt List  1 2
TEXT 184 304 Left 0 !.four 0.5meg V(Sen)
TEXT 192 216 Left 0 !.option noopiter