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Subject: Re: Formula

Date: 12/16/01 at 10:44 PM
Posted by: John Dunn - Consultant
E-mail: ambertec@ieee.org
Message Posted:

In Reply to: Re: Formula posted by Russ Kincaid on 12/16/01 at 7:42 PM:

Hi, Ted.

Following Russ' correct statement, the solution can be taken from the following program. Although written in GWBASIC, it will run in Quick-Basic also:

10 CLS:SCREEN 9:COLOR 15,1:YSTART=50:XSTART=40:PI=3.14159265#
20 PRINT "save "+CHR\$(34)+"dual_rc.bas"+CHR\$(34):PRINT
30 PRINT "save "+CHR\$(34)+"a:\dual_rc.bas"+CHR\$(34):PRINT:PRINT
40 B\$=" E1 E2":LOCATE 7,1:PRINT B\$
50 C\$=" #####.### #####.###":GOTO 90
60 X=T/(R1*C1):Y=E2
70 CC=XSTART+X:DD=(320-Y-YSTART):IF KK0 THEN LINE (AA,BB)-(CC,DD)
80 AA=CC:BB=DD:KK=1:RETURN
100 EIN=-1:I1=EIN/R1:DE1=-I1*DT/C1:E1=E1+DE1
110 I2=(E1-E2)/R2:DE2=I2*DT/C2:E2=E2+DE2:LOCATE 8,1:PRINT USING C\$;E1,E2
120 GOSUB 60:T=T+DT:IF E1>300 THEN GOTO 140
130 GOTO 100
140 END

The components are an input resistor to the integrator called R1, an integrator capacitor called C1, a resistor from the integrator's op-amp output called R2 feeding a shunt capacitor from the output end of R2 which we call C2.

The values shown are R1=10K, R2 = 1 Meg, C1 = 1 µF and C2 = 1 µF. The input voltage to R1 of the integrator is -1 volt.

The voltage at the integrator output is E1 and the voltage across C2 is E2.

This program will draw the output E2 versus time scaled to the integrator's 1/(R1 C1).

This kind of problem, by the way, can be solved using LaPlacian methods, but I kind of like haven't used LaPlace since 1972.(I still remember the incident!)

Give this code a try and if you have problems, please let me know.

Good luck.

John Dunn
ambertec@ieee.org

Re: Formula John Dunn - Consultant   Posted at: 12/16/01 (1)

Re: Formula John Dunn - Consultant   Posted at: 12/16/01 (0)

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