Version 4
SHEET 1 880 680
WIRE 224 16 16 16
WIRE 128 80 96 80
WIRE 304 80 192 80
WIRE 224 128 224 16
WIRE 16 144 16 16
WIRE 96 144 96 80
WIRE 192 144 96 144
WIRE 304 160 304 80
WIRE 304 160 256 160
WIRE 400 160 304 160
WIRE 432 160 400 160
WIRE 192 176 160 176
WIRE 304 192 304 160
WIRE 224 240 224 192
WIRE 400 256 400 160
WIRE 160 288 160 176
WIRE 304 288 304 272
WIRE 304 288 160 288
WIRE 96 304 96 144
WIRE 304 304 304 288
WIRE 16 400 16 224
WIRE 96 400 96 384
WIRE 304 400 304 384
WIRE 400 400 400 336
FLAG 224 240 0
FLAG 16 400 0
FLAG 96 400 0
FLAG 304 400 0
FLAG 432 160 OUT
FLAG 400 400 0
SYMBOL voltage 16 128 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 20V
SYMBOL zener 128 96 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName D1
SYMATTR Value BZX84C6V2L
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 80 288 R0
SYMATTR InstName R1
SYMATTR Value 1k8
SYMBOL res 288 176 R0
SYMATTR InstName R2
SYMATTR Value 10k
SYMBOL res 288 288 R0
SYMATTR InstName R3
SYMATTR Value 10k
SYMBOL current 400 256 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName I1
SYMATTR Value 1m
SYMBOL Opamps\\LT1013 224 96 R0
SYMATTR InstName U1
TEXT 278 42 Left 0 !.dc I1 0 28m 0.1m V1 15 30 5