Version 4 SHEET 1 1404 776 WIRE -80 -16 -80 -32 WIRE -80 160 -80 64 WIRE -80 160 -128 160 WIRE -16 160 -80 160 WIRE 96 160 64 160 WIRE 480 176 352 176 WIRE 496 176 480 176 WIRE 976 176 864 176 WIRE 1008 176 976 176 WIRE -128 192 -128 160 WIRE 96 208 96 160 WIRE 416 224 416 112 WIRE 928 224 928 112 WIRE 352 240 352 176 WIRE 384 240 352 240 WIRE 864 240 864 176 WIRE 896 240 864 240 WIRE -80 256 -80 160 WIRE 496 256 496 176 WIRE 496 256 448 256 WIRE 544 256 496 256 WIRE 656 256 624 256 WIRE 1008 256 1008 176 WIRE 1008 256 960 256 WIRE 1056 256 1008 256 WIRE 1168 256 1136 256 WIRE 272 272 80 272 WIRE 384 272 272 272 WIRE 896 272 864 272 WIRE 656 288 656 256 WIRE 1168 288 1168 256 WIRE 80 304 80 272 WIRE -80 368 -80 336 WIRE 416 384 416 288 WIRE 928 384 928 288 WIRE 80 416 80 384 FLAG 80 416 COM FLAG 272 272 IN FLAG 416 112 +12V FLAG 416 384 -12V FLAG 480 176 OUT1 FLAG 976 176 OUT3 FLAG 928 112 +12V FLAG 928 384 -12V FLAG 864 272 in FLAG -80 -32 +12V FLAG -80 368 -12V FLAG 656 288 COM FLAG 1168 288 COM FLAG 96 208 COM FLAG -128 192 0 SYMBOL voltage 80 288 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value SINE(0 5 100 2m5 5 0 1) SYMBOL voltage -80 -32 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value 12 SYMBOL res 528 272 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 0 56 VBottom 0 SYMATTR InstName R1 SYMATTR Value 500 SYMBOL res 1040 272 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 0 56 VBottom 0 SYMATTR InstName R3 SYMATTR Value 500 SYMBOL voltage -80 240 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V3 SYMATTR Value 12 SYMBOL voltage 80 160 R90 WINDOW 0 -32 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName VGND SYMATTR Value 0 SYMBOL Robertugo\\OPAMP5 416 192 R0 SYMATTR InstName U1 SYMATTR SpiceModel TL072 SYMBOL Robertugo\\OPAMP5 928 192 R0 SYMATTR InstName U2 SYMATTR SpiceModel TL072s TEXT -192 -320 Left 0 !.tran 0 15m 0 100u TEXT -192 -288 Left 0 !.options plotwinsize=0 TEXT 168 -344 Left 0 ;The model TL072s is a TL072 model which is enhanced by a load-current model. TEXT 176 -288 Left 0 ;Original begin of the TL072 model\n \n.SUBCKT TL072 1 2 3 4 5\n*\n..... TEXT 616 -288 Left 0 ;Enhanced model\n \n.SUBCKT TL072s 1 2 3 4 5out\n*\n.PARAM IQ=-10m ; Compensate the wrong quiescent current\n \nV1 5 5out 0\nG1 3 0 VALUE={if((I(V1)>0),(I(V1)+IQ),IQ)}\nG2 0 4 VALUE={if((I(V1)<0),(-I(V1)+IQ),IQ)}\n*\n..... TEXT 176 -64 Left 0 ;Plot Ix(U1:V+) and Ix(U2:V+) TEXT 952 336 Left 0 ;Enhanced version TEXT 168 -712 Left 0 ;Please don't use this GND-current measurement method as your standard\nway for all circuits.\nIt's only a study to show how to fulfill a very very exceptional requirement.\nBetter you forget this all because this adds unnecessary complexity\nto your circuit for normal applications.\n \n \nThe normal net COM is used to help for current measurement.\nThis seperation of the GND(also known as 0) net allows to measure \nthe total current flowing back to the supply's ground.\nThe COM net has the advantage of a nice symbol over the normal net names.\nPlot I(VGND) to measure the current. TEXT 0 48 Left 0 ;GND-current meter\nI(VGND)