Version 4 SHEET 1 880 680 WIRE 80 80 -48 80 WIRE 208 80 80 80 WIRE 256 80 208 80 WIRE -48 144 -48 80 WIRE 352 144 144 144 WIRE 208 160 208 80 WIRE 144 176 144 144 WIRE 176 176 144 176 WIRE 272 192 240 192 WIRE 352 192 352 144 WIRE 400 192 352 192 WIRE 80 208 80 160 WIRE 176 208 80 208 WIRE -48 288 -48 224 WIRE 80 288 -48 288 WIRE 208 288 208 224 WIRE 208 288 80 288 WIRE 256 288 208 288 FLAG 400 192 0 SYMBOL res 64 64 R0 SYMATTR InstName R1 SYMATTR Value 220k SYMBOL res 64 192 R0 SYMATTR InstName R2 SYMATTR Value 220k SYMBOL Opamps\\OP07 208 128 R0 SYMATTR InstName U1 SYMBOL voltage -48 128 R0 SYMATTR InstName V1 SYMATTR Value 15 SYMBOL res 368 176 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R3 SYMATTR Value 1k TEXT -80 296 Left 2 !.tran 1