Version 4
SHEET 1 996 680
WIRE 720 16 384 16
WIRE 720 48 720 16
WIRE -64 80 -96 80
WIRE -48 80 -64 80
WIRE 64 80 32 80
WIRE 192 80 144 80
WIRE 288 80 192 80
WIRE 192 96 192 80
WIRE 416 112 320 112
WIRE 528 112 496 112
WIRE -96 144 -96 80
WIRE 384 144 384 16
WIRE 320 160 320 112
WIRE 352 160 320 160
WIRE 528 176 528 112
WIRE 528 176 416 176
WIRE 640 176 528 176
WIRE 720 176 720 128
WIRE 720 176 672 176
WIRE 288 192 288 80
WIRE 352 192 288 192
WIRE 640 208 640 176
WIRE 720 208 720 176
WIRE -96 304 -96 224
WIRE -96 304 -240 304
WIRE -64 304 -96 304
WIRE -48 304 -64 304
WIRE 64 304 32 304
WIRE 320 304 320 160
WIRE 320 304 144 304
WIRE 192 320 192 176
WIRE 272 320 192 320
WIRE 640 320 640 288
WIRE 640 320 272 320
WIRE 672 320 672 176
WIRE 672 320 640 320
WIRE 192 352 192 320
WIRE 384 352 384 208
WIRE 720 352 720 288
WIRE 720 352 384 352
WIRE -240 400 -240 384
WIRE 272 400 272 320
WIRE 272 400 -240 400
FLAG 192 352 0
FLAG -64 80 in+
FLAG -64 304 in-
FLAG 640 176 out
SYMBOL res 48 64 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R1
SYMATTR Value 680k
SYMBOL res 208 192 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R2
SYMATTR Value 4.75k
SYMBOL res 48 288 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 680k
SYMBOL res 400 128 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R4
SYMATTR Value 4.7k
SYMBOL voltage 720 32 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL voltage 720 192 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value 5
SYMBOL voltage -96 128 R0
WINDOW 3 23 85 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value 250
SYMATTR InstName V3
SYMBOL res 656 304 R180
WINDOW 0 36 76 Left 2
WINDOW 3 36 40 Left 2
SYMATTR InstName R5
SYMATTR Value 1k
SYMBOL Opamps\\LT1630 384 112 R0
SYMATTR InstName U1
SYMBOL res 160 64 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R6
SYMATTR Value 680k
SYMBOL res 160 288 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R7
SYMATTR Value 680k
SYMBOL voltage -240 288 R0
WINDOW 3 23 85 Left 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR Value PWL(0 50 1 250)
SYMATTR InstName V4
TEXT 280 376 Left 2 !.tran 1
TEXT 120 -8 Left 2 ;.step param R2 4.5k 5.5k 0.25k
TEXT 480 -16 Left 2 ;R=limit(4.5k,4.9k, 4.5k+400*TIME)