Version 4
SHEET 1 880 1288
WIRE -656 -128 -656 -192
WIRE -656 112 -656 -48
WIRE -656 144 -656 112
WIRE -656 256 -656 224
WIRE -560 112 -656 112
WIRE -560 176 -560 112
WIRE -432 144 -432 -32
WIRE -432 240 -432 208
WIRE -400 -32 -432 -32
WIRE -336 240 -432 240
WIRE -336 304 -336 240
WIRE -336 400 -336 384
WIRE -320 -32 -320 -128
WIRE -320 16 -320 -32
WIRE -176 -128 -256 -128
WIRE -176 -112 -176 -128
WIRE -176 -32 -256 -32
WIRE -176 80 -176 0
WIRE -144 -32 -176 -32
WIRE -144 0 -176 0
WIRE -32 -128 -176 -128
WIRE -32 -16 -80 -16
WIRE -32 -16 -32 -128
WIRE 368 -16 -32 -16
WIRE 368 32 368 -16
WIRE 656 32 368 32
FLAG -560 176 0
FLAG -336 400 0
FLAG 656 32 Vout
IOPIN 656 32 Out
FLAG -656 -192 V1
FLAG -656 256 V2
FLAG -112 -48 V1
FLAG -112 16 V2
FLAG -176 80 0
FLAG -320 96 0
SYMBOL voltage -656 -144 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 15
SYMBOL voltage -656 128 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value 15
SYMBOL voltage -336 288 R0
WINDOW 123 24 132 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value2 AC 1V 0
SYMATTR InstName V3
SYMATTR Value 0
SYMBOL Opamps\\LT1001 -112 -80 R0
SYMATTR InstName U1
SYMBOL res -160 -16 R180
WINDOW 0 36 76 Left 0
WINDOW 3 36 40 Left 0
SYMATTR InstName R4
SYMATTR Value {Rc}
SYMBOL cap -448 144 R0
SYMATTR InstName C1
SYMATTR Value 1000µF
SYMBOL cap -256 -144 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C2
SYMATTR Value {Ca}
SYMBOL cap -256 -48 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C3
SYMATTR Value {Ca}
SYMBOL res -336 0 R0
SYMATTR InstName R1
SYMATTR Value {Rb}
SYMBOL res -416 -48 M90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R2
SYMATTR Value {Ra}
TEXT -64 298 Left 0 !.ac dec 1000 1e-3 1e6
TEXT -96 208 Left 0 !.PARAM Ra=13K Rb=820 Rc=75K Ca=0.027
TEXT -224 248 Left 0 ;Fc is supposed to be 750Hz and bandwidth is supposed to be 150Hz.\nSee "instructions" below.
TEXT -512 488 Left 0 ;The calculations are fairly simple. You need to determine several\nthings first, Ho the gain per stage, Q the bandwidth and Wo which is\n2 * pi * Fc.\n  Finally pick a convenient value for C which if reasonably large, leads\nto smaller values of resistance and consequently some aid in reducing noise.\n  The capacitor and resistor values are simply the value of C you choose\nto use and the resistor values result from the following calculations.\n \n        Active band pass filter calculations\n \n  We'll proceed with a typical design example and say we need an audio filter\nfor a CW receiver. Fc will be 750 Hz, gain per stage we'll fix at 3 and\nwe'll make the bandwidth 150 Hz leading to Q = 750 / 150 = 5. For convenience\nC will equal 0.027 uF being a polyester capacitor we have on hand.\n \n        Calculate R1 firstly:\nR1 = Q / [ Ho * Wo * C ]\n= 5 / [ 3 * 4712.4 * 0.027 X 10E-6 ]\n= 5 / 0.0003817 = 13099 or 13K\n \n        Next calculate R2:\nR2 = Q / [ ( 2 * Q^2 - Ho ) * C * Wo ]\n= 5 / [ ( 2 * 5^2 - 3 ) * 0.027 X 10E-6 * 4712.4 ]\n= 5 / [ (50 - 3 ) * 0.000127234 ] = 5 / .00598 = 836 or 820R\n \n        Finally calculate R3:\nR3 = 2 * Q / [ C * Wo ]\n= 10 / [ 0.027 X 10E-6 * 4712.4 ]\n= 10 / [ 0.000127234 ] = 78,595 or 75K