Version 4
SHEET 1 880 744
WIRE 304 -272 128 -272
WIRE 464 -272 304 -272
WIRE 624 -272 464 -272
WIRE 128 -240 128 -272
WIRE 624 -240 624 -272
WIRE 464 -224 464 -272
WIRE 128 -128 128 -160
WIRE 624 -128 624 -160
WIRE 656 -128 624 -128
WIRE 304 -112 304 -272
WIRE 464 -80 464 -160
WIRE 560 -80 464 -80
WIRE 624 -16 624 -32
WIRE 624 -16 576 -16
WIRE 672 -16 624 -16
WIRE 704 -16 672 -16
WIRE 576 16 576 -16
WIRE 48 64 48 48
WIRE 112 64 48 64
WIRE 224 64 192 64
WIRE 304 96 304 -32
WIRE 352 96 304 96
WIRE 528 96 432 96
WIRE 48 128 48 64
WIRE 304 128 304 96
WIRE 672 128 672 -16
WIRE 224 176 224 64
WIRE 240 176 224 176
WIRE 464 176 464 -80
WIRE 48 272 48 208
WIRE 304 288 304 224
WIRE 464 288 464 256
WIRE 464 288 304 288
WIRE 576 288 576 112
WIRE 576 288 464 288
WIRE 672 288 672 192
WIRE 672 288 576 288
WIRE 672 320 672 288
FLAG 48 48 Vdrive1
FLAG 48 272 0
FLAG 672 320 0
FLAG 624 -272 VccHard+
FLAG 704 -16 ramp
FLAG 128 -128 0
FLAG 656 -128 Ve
SYMBOL cap 656 128 R0
SYMATTR InstName C1
SYMATTR Value {c}
SYMBOL voltage 48 112 R0
WINDOW 0 24 28 Left 0
WINDOW 3 -19 227 Left 0
WINDOW 123 0 0 Left 0
WINDOW 39 18 139 Left 0
SYMATTR InstName V1
SYMATTR Value PULSE(0 14 10us 10ns 10ns 20us 40us)
SYMBOL pnp 560 -32 M180
WINDOW 0 58 23 Left 0
WINDOW 3 62 51 Left 0
SYMATTR InstName Q1
SYMATTR Value BC557C
SYMBOL zener 480 -160 R180
WINDOW 0 -19 72 Left 0
WINDOW 3 -124 -8 Left 0
SYMATTR InstName D1
SYMATTR Value BZX84C10L
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 448 160 R0
SYMATTR InstName R2
SYMATTR Value 2k2
SYMBOL res 608 -256 R0
SYMATTR InstName R3
SYMATTR Value 4k6
SYMBOL nmos 528 16 R0
SYMATTR InstName M1
SYMATTR Value BSS123
SYMBOL res 208 48 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R5
SYMATTR Value 3k3
SYMBOL voltage 128 -256 R0
WINDOW 0 24 28 Left 0
WINDOW 3 25 85 Left 0
WINDOW 123 0 0 Left 0
WINDOW 39 18 139 Left 0
SYMATTR InstName V2
SYMATTR Value 15VDC
SYMBOL npn 240 128 R0
SYMATTR InstName Q3
SYMATTR Value BC547C
SYMBOL res 288 -128 R0
SYMATTR InstName R4
SYMATTR Value 1k
SYMBOL res 448 80 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R1
SYMATTR Value 10
TEXT 40 408 Left 0 !.tran 0.1ms
TEXT 144 -416 Left 0 !.step param c list  2nF  4nF 6nF\n;.step param r list  500 1k 2k 4k
TEXT 248 -360 Left 0 !.ic V(ramp)=0V