Theoretical design, one goal was to remove need for tweaking. Version 4 SHEET 1 1400 708 WIRE 1232 -240 1168 -240 WIRE 1232 -224 1232 -240 WIRE -384 -208 -512 -208 WIRE 224 -208 -384 -208 WIRE 432 -208 384 -208 WIRE 576 -208 512 -208 WIRE 656 -208 624 -208 WIRE 768 -208 736 -208 WIRE 624 -176 624 -208 WIRE 224 -160 224 -208 WIRE -512 -144 -512 -208 WIRE 480 -128 464 -128 WIRE 1232 -128 1232 -144 WIRE -176 -112 -208 -112 WIRE -64 -112 -96 -112 WIRE -32 -112 -64 -112 WIRE 80 -112 48 -112 WIRE 464 -96 464 -128 WIRE -384 -80 -384 -208 WIRE 384 -80 384 -208 WIRE 432 -80 384 -80 WIRE -64 -64 -64 -112 WIRE 80 -64 80 -112 WIRE 576 -64 576 -208 WIRE 576 -64 496 -64 WIRE 608 -64 576 -64 WIRE 656 -64 608 -64 WIRE 768 -64 768 -208 WIRE 768 -64 736 -64 WIRE 848 -64 768 -64 WIRE 960 -64 928 -64 WIRE 1008 -64 960 -64 WIRE 224 -48 224 -80 WIRE 432 -48 224 -48 WIRE -512 -32 -512 -64 WIRE 1120 -32 1088 -32 WIRE 1232 -32 1200 -32 WIRE 224 -16 224 -48 WIRE 384 -16 384 -80 WIRE 464 -16 464 -32 WIRE 1232 -16 1232 -32 WIRE 848 16 816 16 WIRE -384 32 -384 0 WIRE -64 48 -64 16 WIRE 816 48 816 16 WIRE 768 64 768 -64 WIRE 784 64 768 64 WIRE 960 80 960 -64 WIRE 960 80 848 80 WIRE 1088 80 1088 -32 WIRE 1088 80 960 80 WIRE 1120 80 1088 80 WIRE 1232 80 1232 48 WIRE 1232 80 1200 80 WIRE 1296 80 1232 80 WIRE 224 96 224 64 WIRE 384 96 384 64 WIRE 784 96 768 96 WIRE 80 112 80 16 WIRE 80 112 -80 112 WIRE 816 128 816 112 WIRE 1232 144 1232 80 WIRE -16 160 -32 160 WIRE -32 192 -32 160 WIRE -80 208 -80 112 WIRE -64 208 -80 208 WIRE 384 208 384 176 WIRE 432 208 384 208 WIRE 576 208 512 208 WIRE 608 208 576 208 WIRE 656 208 608 208 WIRE 768 208 768 96 WIRE 768 208 736 208 WIRE 816 208 768 208 WIRE 928 208 896 208 WIRE 48 224 0 224 WIRE 80 224 80 112 WIRE 80 224 48 224 WIRE -384 240 -384 112 WIRE -256 240 -384 240 WIRE -96 240 -176 240 WIRE -64 240 -96 240 WIRE 1232 256 1232 224 WIRE -32 272 -32 256 WIRE 480 288 464 288 WIRE 464 320 464 288 WIRE 768 320 768 208 WIRE 816 320 768 320 WIRE 928 320 896 320 WIRE -384 336 -384 240 WIRE 384 336 384 208 WIRE 432 336 384 336 WIRE 576 352 576 208 WIRE 576 352 496 352 WIRE -96 368 -96 240 WIRE 432 368 -96 368 WIRE 928 368 928 320 WIRE 1232 368 1232 336 WIRE 80 400 80 224 WIRE 464 400 464 384 WIRE -384 448 -384 416 WIRE -48 496 -80 496 WIRE 80 496 80 480 WIRE 80 496 32 496 WIRE -80 528 -80 496 WIRE -80 624 -80 608 FLAG -384 448 0 FLAG -32 272 0 FLAG 224 96 0 FLAG 1232 -128 0 FLAG -80 624 0 FLAG -64 48 0 FLAG 464 -16 0 FLAG 464 400 0 FLAG 816 128 0 FLAG 928 368 0 FLAG 1232 368 0 FLAG 624 -176 0 FLAG -512 -32 0 FLAG 1008 -64 o4 IOPIN 1008 -64 Out FLAG 608 208 o3 FLAG 608 -64 o2 FLAG 48 224 o1 FLAG 1296 80 out IOPIN 1296 80 Out FLAG 1168 -240 vcc IOPIN 1168 -240 Out FLAG 928 208 vcc IOPIN 928 208 In FLAG -16 160 vcc IOPIN -16 160 In FLAG 480 288 vcc IOPIN 480 288 In FLAG 480 -128 vcc IOPIN 480 -128 In FLAG -208 -112 vcc IOPIN -208 -112 In FLAG 848 16 vcc IOPIN 848 16 In SYMBOL res -400 -96 R0 WINDOW 0 36 54 Left 2 WINDOW 3 30 79 Left 2 SYMATTR InstName TR1 SYMATTR Value 18.2K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res -400 16 R0 WINDOW 0 38 41 Left 2 WINDOW 3 38 76 Left 2 SYMATTR InstName R1 SYMATTR Value 549 SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res -400 320 R0 WINDOW 0 47 48 Left 2 WINDOW 3 37 79 Left 2 SYMATTR InstName PC SYMATTR Value {PC} SYMBOL Opamps\\opamp2 -32 160 R0 WINDOW 3 23 92 Left 2 SYMATTR Value AD8605 SYMATTR InstName U1 SYMBOL res 208 -176 R0 WINDOW 0 45 43 Left 2 WINDOW 3 37 92 Left 2 SYMATTR InstName RTAA SYMATTR Value {20K-TA} SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 208 -32 R0 WINDOW 0 42 74 Left 2 WINDOW 3 45 40 Left 2 SYMATTR InstName RTAB SYMATTR Value {TA} SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL Misc\\battery 1232 -240 R0 WINDOW 0 9 6 Left 2 WINDOW 3 33 84 Left 2 SYMATTR InstName VBAT SYMATTR Value 5.0V SYMBOL res -96 512 R0 WINDOW 0 1 32 Right 2 WINDOW 3 -10 68 Right 2 SYMATTR InstName RM1 SYMATTR Value 1K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 64 384 R0 WINDOW 0 39 39 Left 2 WINDOW 3 34 70 Left 2 SYMATTR InstName TR2A SYMATTR Value 45.3K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res -64 512 R270 WINDOW 0 55 80 VLeft 2 WINDOW 3 -19 80 VLeft 2 SYMATTR InstName TR2B SYMATTR Value {TR2} SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 64 -128 R90 WINDOW 0 -20 39 VRight 2 WINDOW 3 46 38 VRight 2 SYMATTR InstName R92 SYMATTR Value 976K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res -80 -128 R90 WINDOW 0 -19 36 VRight 2 WINDOW 3 50 26 VRight 2 SYMATTR InstName R91 SYMATTR Value 5Meg SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res -48 32 R180 WINDOW 0 -12 70 Right 2 WINDOW 3 -12 35 Right 2 SYMATTR InstName R93 SYMATTR Value 0.001 SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 64 -80 R0 SYMATTR InstName R90 SYMATTR Value 7.5K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL Opamps\\opamp2 464 -128 R0 WINDOW 3 17 95 Left 2 SYMATTR Value AD8605 SYMATTR InstName U2 SYMBOL Opamps\\opamp2 464 288 R0 WINDOW 3 26 95 Left 2 SYMATTR Value AD8605 SYMATTR InstName U3 SYMBOL res 528 -224 R90 WINDOW 0 -16 39 VRight 2 WINDOW 3 48 28 VRight 2 SYMATTR InstName R2 SYMATTR Value 100K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 528 192 R90 WINDOW 0 -17 30 VRight 2 WINDOW 3 48 16 VRight 2 SYMATTR InstName R3 SYMATTR Value 100K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 368 80 R0 WINDOW 0 33 46 Left 2 WINDOW 3 36 74 Left 2 SYMATTR InstName R4 SYMATTR Value 10K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 368 -32 R0 WINDOW 0 40 62 Left 2 WINDOW 3 41 90 Left 2 SYMATTR InstName R5 SYMATTR Value {250K-SENS} SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL Opamps\\opamp2 816 16 R0 WINDOW 3 26 94 Left 2 SYMATTR Value AD8605 SYMATTR InstName U4 SYMBOL res 752 192 R90 WINDOW 0 -23 46 VRight 2 WINDOW 3 53 31 VRight 2 SYMATTR InstName R6 SYMATTR Value 20.0K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 752 -80 R90 WINDOW 0 -17 46 VRight 2 WINDOW 3 53 31 VRight 2 SYMATTR InstName R7 SYMATTR Value 20.0K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 944 -80 R90 WINDOW 0 -24 44 VRight 2 WINDOW 3 49 34 VRight 2 SYMATTR InstName R8 SYMATTR Value 100K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 912 192 R90 WINDOW 0 -16 46 VRight 2 WINDOW 3 51 35 VRight 2 SYMATTR InstName R9 SYMATTR Value 200K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 912 304 R90 WINDOW 0 -18 40 VRight 2 WINDOW 3 51 31 VRight 2 SYMATTR InstName R10 SYMATTR Value 100K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 1216 64 R90 WINDOW 0 -20 44 VRight 2 WINDOW 3 51 33 VRight 2 SYMATTR InstName R11 SYMATTR Value 47.0K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 1216 -48 R90 WINDOW 0 -18 37 VRight 2 WINDOW 3 53 32 VRight 2 SYMATTR InstName R12 SYMATTR Value 4.73K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL polcap 1216 -16 R0 SYMATTR InstName C1
SYMBOL res 1216 128 R0 SYMATTR InstName R13 SYMATTR Value 2.20k SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 1216 240 R0 WINDOW 0 86 33 Right 2 WINDOW 3 70 70 Right 2 SYMATTR InstName RM2 SYMATTR Value 1K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 752 -224 R90 WINDOW 0 -19 36 VRight 2 WINDOW 3 44 32 VRight 2 SYMATTR InstName R14 SYMATTR Value 200K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL voltage -512 -160 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value 1.91V SYMBOL voltage -160 240 R90 WINDOW 0 -32 56 VBottom 2 WINDOW 3 35 85 VTop 2 WINDOW 123 35 38 VTop 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V2 SYMATTR Value 0 SYMATTR Value2 AC 1 TEXT -392 -392 Left 2 ;.INCLUDE D:\\SPICE\\AD8605.LIB TEXT -392 -360 Left 2 !.PARAM TA=8.00K TR2=1.25K PC=12.5K SENS=249K TEXT 96 488 Left 2 ;*5K pot TEXT -392 -328 Left 2 !;op TEXT -392 -544 Left 2 !.noise V(o4) V2 oct 50 1E-1 1E6 TEXT -392 -432 Left 2 !.include ad8605.cir TEXT -392 -472 Left 2 ;.ac dec 100 1 100k TEXT -392 -504 Left 2 ;.dc V1 1.9 1.92 1m TEXT -248 160 Left 2 ;INoise TEXT 992 -104 Left 2 ;ONoise TEXT -24 -544 Left 2 ;V2 is required for the analysis. TEXT -504 -232 Left 2 ;Bridge Circuit TEXT 320 -352 Left 2 ;"TA" is tone arm, "RM1" and "RM2" are indicating meter internal resistance. LINE Normal 336 160 160 160 LINE Normal 336 -256 336 160 LINE Normal -576 -256 336 -256 LINE Normal -576 16 -576 -256 LINE Normal -448 16 -576 16 LINE Normal -448 512 -448 16 LINE Normal -304 512 -448 512 LINE Normal -304 -176 -304 512 LINE Normal 160 -176 -304 -176 LINE Normal 160 160 160 -176 RECTANGLE Normal -160 304 -272 144 RECTANGLE Normal 1072 -16 976 -128