Version 4
SHEET 1 880 776
WIRE 224 -64 16 -64
WIRE 432 -64 224 -64
WIRE 16 0 16 -64
WIRE 224 0 224 -64
WIRE 432 0 432 -64
WIRE 16 160 16 80
WIRE 80 160 16 160
WIRE 224 160 224 80
WIRE 224 160 160 160
WIRE 288 160 224 160
WIRE 432 160 432 80
WIRE 432 160 368 160
WIRE 224 192 224 160
FLAG 224 192 0
SYMBOL voltage 64 160 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 -32 56 VBottom 2
SYMATTR InstName V1
SYMATTR Value 10
SYMBOL voltage 272 160 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 -32 56 VBottom 2
SYMATTR InstName V2
SYMATTR Value 20
SYMBOL Misc\\EuropeanResistor 208 -16 R0
SYMATTR InstName R2
SYMATTR Value 10
SYMBOL Misc\\EuropeanResistor 0 -16 R0
SYMATTR InstName R1
SYMATTR Value 15
SYMBOL Misc\\EuropeanResistor 416 -16 R0
SYMATTR InstName R3
SYMATTR Value 10
TEXT 8 -128 Left 2 !.op
TEXT 56 -24 Left 2 ;I1
TEXT 456 -24 Left 2 ;I2
TEXT 248 -24 Left 2 ;I1-I2
TEXT -8 312 Left 2 ;Einschränkungen für die Wahl von R2\n \nI1*(R1+R2) -I2*R2 -Ua = 0 (1)\n \n-I1*R2  +I2*(R2+R3) -Ub = 0 (2)\n \nAus (1)\n \nR1 = (Ua -(I1-I2)*R2)/I1\n \nBedingung:  R2 < Ua/(I1-I2)\n \nAus (2)\n \nR3 = (Ub -(I2-I1)*R2)/I2\n \nBedingung: R2 < Ub/(I2-I1)
LINE Normal 0 -16 16 -32 2
LINE Normal 32 -16 16 -32 2
LINE Normal 416 -32 432 -16 2
LINE Normal 448 -32 432 -16 2
LINE Normal 208 -32 224 -16 2
LINE Normal 240 -32 224 -16 2