Version 4
SHEET 1 880 680
WIRE 48 -192 -48 -192
WIRE 176 -192 48 -192
WIRE 496 -192 176 -192
WIRE 48 -144 48 -192
WIRE 176 -112 176 -192
WIRE -48 -64 -48 -192
WIRE 48 -48 48 -80
WIRE 176 32 176 -32
WIRE -48 80 -48 16
WIRE 48 80 48 16
WIRE 48 80 -48 80
WIRE 112 80 48 80
WIRE 48 144 48 80
WIRE 176 192 176 128
WIRE 496 240 496 -192
WIRE 48 272 48 224
WIRE 176 304 176 272
WIRE -144 320 -208 320
WIRE -16 320 -64 320
WIRE -208 368 -208 320
WIRE 176 384 176 368
WIRE -208 496 -208 448
WIRE 48 496 48 368
WIRE 48 496 -208 496
WIRE 176 496 176 448
WIRE 176 496 48 496
WIRE 496 496 496 304
WIRE 496 496 176 496
FLAG 48 496 0
SYMBOL npn -16 272 R0
SYMATTR InstName Q2
SYMBOL res -48 304 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 4k7
SYMBOL Misc\\signal -208 352 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value PULSE(-3 3 0 1n 1n 30u 60u)
SYMBOL Misc\\cell 496 240 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value 20
SYMBOL res 32 128 R0
SYMATTR InstName R1
SYMATTR Value 4k7
SYMBOL zener 64 16 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D1
SYMATTR Value TFZ6_2B
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL pnp 112 128 M180
SYMATTR InstName Q1
SYMBOL res 160 -128 R0
SYMATTR InstName R3
SYMATTR Value 100
SYMBOL res 160 176 R0
SYMATTR InstName R4
SYMATTR Value 100
SYMBOL diode 32 -144 R0
SYMATTR InstName D3
SYMATTR Value 1N4148
SYMBOL diode 160 304 R0
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL diode 160 384 R0
SYMATTR InstName D4
SYMATTR Value 1N4148
SYMBOL res -64 -80 R0
SYMATTR InstName R5
SYMATTR Value 5k
TEXT -242 510 Left 2 !.tran 0 100u 0 1u