* SPICE netlist
V1 Vcc 0 5
V2 0 Vee 1
RPT V1 V2 {PT}
XU2 X1 X3 Vcc Vee Diff_Out1 LT1001 ;pnba In+)In-)V+)V-)OUT
R3 Diff_Out1 X3 21.1k
R_PT_L2 X1 V1 0.5
R_PT_L1 V2 0 0.5
RL Vref X1 10k
R1 Vref X3 10k
R2 X3 0 963
V3 Vref 0 5
XU1 X11 X13 Vcc Vee Diff_Out2 LT1001 ;pnba In+)In-)V+)V-)OUT
R4 Diff_Out2 X13 22k
RL1 Vref X11 12k
R7 Vref X13 12k
R8 X13 0 1k
RPT1 N006 N005 {PT}
R_PT_L3 X11 N006 0.5
R_PT_L4 N005 0 0.5
.op
.step param PT 920 1400 10

* LTspice schematic (.asc)
Version 4
SHEET 1 3008 688
WIRE 656 -312 608 -312
WIRE 816 -312 736 -312
WIRE 1424 -312 1424 -344
WIRE 1424 -312 1344 -312
WIRE 1504 -312 1424 -312
WIRE -1248 -296 -1296 -296
WIRE -1088 -296 -1168 -296
WIRE -480 -296 -480 -328
WIRE -480 -296 -560 -296
WIRE -400 -296 -480 -296
WIRE 528 -200 400 -200
WIRE 608 -200 608 -312
WIRE 1344 -200 1344 -232
WIRE -1376 -184 -1504 -184
WIRE -1296 -184 -1296 -296
WIRE 608 -184 608 -200
WIRE 672 -184 608 -184
WIRE 1504 -184 1504 -232
WIRE -1296 -168 -1296 -184
WIRE -1232 -168 -1296 -168
WIRE -560 -168 -560 -216
WIRE -400 -168 -400 -216
WIRE -112 -168 -112 -184
WIRE -112 -168 -160 -168
WIRE 16 -168 16 -184
WIRE 16 -168 -112 -168
WIRE 816 -168 816 -312
WIRE 816 -168 736 -168
WIRE 1072 -168 816 -168
WIRE -1088 -152 -1088 -296
WIRE -1088 -152 -1168 -152
WIRE -832 -152 -1088 -152
WIRE -112 -152 -112 -168
WIRE 672 -152 608 -152
WIRE -1232 -136 -1296 -136
WIRE 1504 -136 1504 -184
WIRE -400 -120 -400 -168
WIRE 528 -104 400 -104
WIRE 608 -104 608 -152
WIRE -1376 -88 -1504 -88
WIRE -1296 -88 -1296 -136
WIRE 1344 -56 1344 -72
WIRE 1408 -56 1344 -56
WIRE 1504 -56 1408 -56
WIRE -560 -40 -560 -88
WIRE -496 -40 -560 -40
WIRE -400 -40 -496 -40
WIRE 1408 -40 1408 -56
WIRE -496 -24 -496 -40
WIRE -1360 312 -1504 312
WIRE -1248 312 -1248 216
WIRE -1248 312 -1280 312
WIRE -1216 312 -1248 312
WIRE -1104 312 -1104 216
WIRE -1104 312 -1136 312
WIRE -1056 312 -1104 312
WIRE -784 312 -976 312
WIRE 816 344 672 344
WIRE 960 344 896 344
WIRE 1120 344 1040 344
WIRE 1392 344 1200 344
FLAG -160 -168 0
FLAG -112 -264 Vcc
FLAG -112 -72 Vee
FLAG -1200 -184 Vcc
FLAG -1200 -120 Vee
FLAG -832 -152 Diff_Out1
FLAG -1504 312 X2
FLAG -784 312 X1
FLAG -1248 216 V2
FLAG -1104 216 V1
FLAG -1504 -184 X3
FLAG -1504 -88 X1
FLAG -560 -88 X2
FLAG -560 -168 X1
FLAG -496 -24 0
FLAG -400 -168 X3
FLAG 16 -264 Vref
FLAG -480 -328 Vref
FLAG 704 -200 Vcc
FLAG 704 -136 Vee
FLAG 1072 -168 Diff_Out2
FLAG 400 -200 X13
FLAG 400 -104 X11
FLAG 1344 -72 X12
FLAG 1344 -200 X11
FLAG 1408 -40 0
FLAG 1504 -184 X13
FLAG 1424 -344 Vref
FLAG 672 344 X12
FLAG 1392 344 X11
SYMBOL voltage -112 -280 R0
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL voltage -112 -168 R0
SYMATTR InstName V2
SYMATTR Value 1
SYMBOL res -1120 296 R90
SYMATTR InstName RPT
SYMATTR Value {PT}
SYMBOL OpAmps\\LT1001 -1200 -216 R0
SYMATTR InstName U2
SYMBOL res -1152 -312 R90
SYMATTR InstName R3
SYMATTR Value 21.1k
SYMBOL res -1280 -200 R90
SYMATTR InstName R100
SYMATTR Value 0
SYMBOL res -1280 -104 R90
SYMATTR InstName R200
SYMATTR Value 0
SYMBOL res -960 296 R90
SYMATTR InstName R_PT_L2
SYMATTR Value 0.5
SYMBOL res -1264 296 R90
SYMATTR InstName R_PT_L1
SYMATTR Value 0.5
SYMBOL res -576 -312 R0
SYMATTR InstName RL
SYMATTR Value 10k
SYMBOL res -416 -312 R0
SYMATTR InstName R1
SYMATTR Value 10k
SYMBOL res -416 -136 R0
SYMATTR InstName R2
SYMATTR Value 963
SYMBOL voltage 16 -280 R0
SYMATTR InstName V3
SYMATTR Value 5
SYMBOL OpAmps\\LT1001 704 -232 R0
SYMATTR InstName U1
SYMBOL res 752 -328 R90
SYMATTR InstName R4
SYMATTR Value 22k
SYMBOL res 624 -216 R90
SYMATTR InstName R5
SYMATTR Value 0
SYMBOL res 624 -120 R90
SYMATTR InstName R6
SYMATTR Value 0
SYMBOL res 1328 -328 R0
SYMATTR InstName RL1
SYMATTR Value 12k
SYMBOL res 1488 -328 R0
SYMATTR InstName R7
SYMATTR Value 12k
SYMBOL res 1488 -152 R0
SYMATTR InstName R8
SYMATTR Value 1k
SYMBOL res 1056 328 R90
SYMATTR InstName RPT1
SYMATTR Value {PT}
SYMBOL res 1216 328 R90
SYMATTR InstName R_PT_L3
SYMATTR Value 0.5
SYMBOL res 912 328 R90
SYMATTR InstName R_PT_L4
SYMATTR Value 0.5