Version 4
SHEET 1 880 680
WIRE -176 80 -208 80
WIRE -64 80 -96 80
WIRE 112 80 96 80
WIRE 352 80 336 80
WIRE -208 112 -208 80
WIRE -96 112 -96 80
WIRE 112 128 112 80
WIRE 352 128 352 80
WIRE 80 144 0 144
WIRE 320 144 288 144
WIRE 0 160 0 144
WIRE 176 160 144 160
WIRE 416 160 384 160
WIRE 528 160 496 160
WIRE 576 160 528 160
WIRE 80 176 64 176
WIRE 320 176 288 176
WIRE 528 176 528 160
WIRE -208 208 -208 192
WIRE -96 208 -96 192
WIRE 112 240 112 192
WIRE 112 240 96 240
WIRE 352 240 352 192
WIRE 352 240 336 240
WIRE -176 256 -208 256
WIRE -64 256 -96 256
WIRE 528 272 528 240
WIRE -208 288 -208 256
WIRE -96 288 -96 256
WIRE 528 352 528 336
WIRE -208 384 -208 368
WIRE -96 384 -96 368
FLAG 96 80 +vcc
IOPIN 96 80 In
FLAG 96 240 -vee
IOPIN 96 240 In
FLAG 0 160 0
FLAG 64 176 in
IOPIN 64 176 In
FLAG 176 160 out1
IOPIN 176 160 Out
FLAG -96 208 0
FLAG -208 208 0
FLAG -96 384 0
FLAG -64 80 +vcc
IOPIN -64 80 Out
FLAG -176 80 -vee
IOPIN -176 80 Out
FLAG -64 256 in
IOPIN -64 256 Out
FLAG 336 80 +vcc
IOPIN 336 80 In
FLAG 336 240 -vee
IOPIN 336 240 In
FLAG 288 144 in
IOPIN 288 144 In
FLAG 576 160 out2
IOPIN 576 160 Out
FLAG 288 176 ref
IOPIN 288 176 In
FLAG -208 384 0
FLAG -176 256 ref
IOPIN -176 256 Out
FLAG 528 352 0
SYMBOL OpAmps\\opamp2 112 96 R0
SYMATTR InstName U1
SYMATTR Value LM741
SYMATTR SpiceModel LM741
SYMBOL voltage -96 96 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 15
SYMBOL voltage -208 96 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value -15
SYMBOL voltage -96 272 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value PULSE(-1 1 0 500u 500u 0 1m)
SYMBOL OpAmps\\opamp2 352 96 R0
SYMATTR InstName U2
SYMATTR Value LM741
SYMATTR SpiceModel LM741
SYMBOL voltage -208 272 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V4
SYMATTR Value 0.5
SYMBOL res 512 144 R90
WINDOW 0 5 56 VBottom 2
WINDOW 3 27 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 1k
SYMBOL zener 512 176 R0
SYMATTR InstName D1
SYMATTR Value Z4V7
SYMBOL zener 544 336 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D2
SYMATTR Value Z4V7
TEXT -208 16 Left 2 !.include wvwspice.lib
TEXT -208 40 Left 2 !.tran 2m