DECLARE SUB PAGER ()
10 DIM I(200), E(200), T(200)
pi = 4! * ATN(1!)
REM ge copeland
REM Dept of Physics
REM Old Dominion University
REM Norfolk VA 23529
REM 2/20/2001
40 REM                                                      
70 PRINT CHR$(12);
100 PRINT "PHASOR analysis of an LRC circuit."
130 PRINT
160 PRINT " This program does an analysis of an ac LRC circuit."
190 PRINT "The generator supplies voltage via E(t)=Emax Sin(2pift)"
PRINT " Helpful values: E max = 100v, f = 60 Hz"
220 PRINT "Input the max Voltage and the frequency in Hz?"
PRINT
250 INPUT Emax, F0
280 W0 = 2 * pi * F0
310 PRINT "Input the values of the inductance, resistance and capacitance?"
PRINT "Helpful values: L=3H,R=200 Ohms, and C = 0.5uF"
340 PRINT "Input L(H),R(Ohms),C(Farads)?"
370 INPUT L, R, C
400 PRINT "The inductive reactance X(L) = W*L"
430 PRINT "where W is the angular frequency of the generator."
460 XL = W0 * L
490 PRINT " X(L) = "; XL; " Ohms."; ""
520 PRINT
550 PRINT " The capacitive reactance = X(C) = 1/(W*C)"
580 XC = 1 / (W0 * C)
610 PRINT " X(C) = "; XC; " Ohms."
640 PRINT
670 Z = SQR(R ^ 2 + (XL - XC) ^ 2)
700 PRINT "The impedance of the circuit Z = sqr( R^2 +(XL_XC)^2)"; ""
730 PRINT "For your values of LRC and W, Z ="; Z; " Ohms"
760 CALL PAGER
790 PRINT "The current and voltage change with time in this ac circuit."
820 PRINT "The current i(t) = i max sin(wt -phi)"
850 PRINT "where w = 2 Pi * frequency, i max = max current and phi is the phase"
880 PRINT "angle in radians. i max = E max/Z and phi is given by"
910 PRINT , "tan(phi) = [X(L)-X(C)]/R"
940 PRINT
970 PHI = ATN((XL - XC) / R)
1000 ANG = PHI * 180! / pi
1030 Imax = Emax / Z
1060 PRINT " The MAXIMUM CURRENT i max ="; Imax; " amperes."
1090 PRINT " The phase angle phi ="; ANG; " degrees"
1120 IF XL > XC THEN PRINT "E max LEADS i max."
1150 IF XC > XL THEN PRINT "E max LAGS  i max."
1180 CALL PAGER
1210 PRINT " BELOW YOU WILL BE GIVEN SEVERAL OPTIONS:"
1240 PRINT " 1. Investigate the time evolution of the circuit."
1270 PRINT " 2. Investigate the evolution of the circuit as the driving"
1300 PRINT "    frequency is varied."
1330 PRINT
1360 PRINT "Input the option you wish to continue study: 1 or 2?"
1390 INPUT ANS
1420 IF ANS = 1 THEN 1510
1450 IF ANS = 2 THEN 3040
1480 GOTO 1210
1510 REM    TIME BEHAVIOR                                       
1540 CALL PAGER
1570 PRINT "TIME BEHAVIOR:"
1600 PRINT " The voltage E(t) and current i(t) are functions of time."
1630 PRINT " E(t) = "; Emax; " * SIN("; W0; "* t ) "
1660 PRINT " i(t) = "; Imax; " * sin("; W0; " t - "; PHI; ")"
1690 PRINT
1720 PRINT "Want to see a plot of these functions vs time?(YES or NO)"
1750 INPUT ANSP$
1780 IF ANSP$ = "YES" OR ANSP$ = "yes" OR ANSP$ = "Yes" THEN 1840
1810 IF ANSP$ = "NO" OR ANSP$ = "no" OR ANSP$ = "No" THEN STOP
1840 PRINT "After the plot return to PHASOR and study the variation with w."
    
2520 REM TEKTRONIX OUT PUT FOR TIME BEHAVIOR                  
2530 OPEN "PLTTEK.dat" FOR OUTPUT AS #2
2542 REM
        IF Imax < Emax THEN
        REM scale it up
        Imax = Emax
        ELSE
        Emax = Imax
        END IF
       NPTS = 0

2544 FOR T1 = 0 TO 5 * pi / W0 STEP 5 * pi / (W0 * 100)
2546 NPTS = NPTS + 1
2548 E(NPTS) = Emax * SIN(W0 * T1)
2600 T(NPTS) = T1
2610 I(NPTS) = Imax * SIN(W0 * T1 - PHI)
2612 NEXT T1
2620 PRINT #2, 1
2650 PRINT #2, 2
2680 PRINT #2, NPTS
2710 PRINT #2, " Voltage & Current Scaled same"
2740 PRINT #2, "TIME IN SECONDS"
2770 PRINT #2, "I(T) AND E(T) VS T FOR LRC CIRCUIT"
2800 PRINT #2, " AC BEHAVIOR FROM PROGRAM PHASOR"
2802 FOR I = 1 TO NPTS
2804 PRINT #2, T(I), E(I)
2806 NEXT I
2808 FOR I = 1 TO NPTS
2810 PRINT #2, T(I), I(I)
2812 NEXT I
REM PRINT #2, T(NPTS - 1), I(NPTS - 1)
REM statement above takes care of a one extra point on graph
REM hope is

2816 PRINT "Now to the Plot using WPLOT."
CLOSE #2
CHAIN "Tek2wplt.bas"
2818 STOP
3040 REM     OPTION 2. BEHAVIOR IF FREQUENCY IS CHANGED.        
3042 CALL PAGER
3044 PRINT "FREQUENCY BEHAVIOR of an LRC circuit."
3046 PRINT
3048 PRINT " Just as a mechanical system has a natural resonance frequency"
3050 PRINT "so does an electrical circuit. This is easily seen for our LRC"
3052 PRINT "circuit, if you recap that the maximum current i max is given as:"
3054 PRINT "               i max   =   E max"
3055 PRINT "                         ------------"
3056 PRINT "                         [ R^2 +{ wL -1/wC}^2 ] ^.5"
3058 PRINT
3060 PRINT " Not this expression has a resonance demoninator. That is it"
3062 PRINT "does change its value as w changes. The current i max varies"
3063 PRINT "with the angular frequency w and has an absolute maximum when"
3064 PRINT " the inductive and capacitive reactances are equal. XL=XC."
3065 PRINT "For this circuit, this happens when w=1/sqrt(LC)."
3066 wr = 1 / SQR(L * C)
3067 PRINT " For your values of LRC, W resonance ="; wr; " radians per sec."
PRINT "or "; wr / (2 * pi); " Hz"
x0 = SQR(L / C)
Q = x0 / R
PRINT " The Q of this circuit is "; Q
3068 CALL PAGER
3070 PRINT "Now we will calculate i max vs w, and plot it."
3120 REM TEKTRONIX OUT PUT FOR TIME BEHAVIOR                    
3122 OPEN "PLTTEK.DAT" FOR OUTPUT AS #2
3124 NPTS = 0
3126 FOR w = .01 * wr TO 2! * wr STEP wr * .01
3128 NPTS = NPTS + 1
3130 E(NPTS) = Emax / (SQR(R ^ 2 + (w * L - 1 / (w * C)) ^ 2))
3132 T(NPTS) = w
3136 NEXT w
3138 PRINT #2, 1
3140 PRINT #2, 1
3142 PRINT #2, NPTS
3144 PRINT #2, " CURRENT MAX"; ""
3146 PRINT #2, "ANGULAR FREQUENCY IN RADS/S"; ""
3148 PRINT #2, "I MAX VS W FOR LRC CIRCUIT"; ""
3150 PRINT #2, " Frequency behavior for Q ="; Q; " from PHASOR1"
3152 FOR I = 1 TO NPTS
3154 PRINT #2, T(I), E(I)
3156 NEXT I
3158 PRINT "Now do the PLOT."
CLOSE #2
CHAIN "Tek2wplt.bas"
3160 STOP

3300 END

3199 SUB PAGER
3200 PRINT , "Push RETURN to continue."
3230 INPUT DUM$
3260 PRINT CHR$(12);
END SUB