Hacker Chronicles 2/HACKER2.BIN/490.NETWORK1.DOC

Text File | 1986-01-21 | 12KB | 566 lines

                            NETWORK.BAS V1.0

                  AC ELECTRONIC CIRCUIT ANALYSIS PROGRAM























                  Configured for the IBM by:         Bruce A. Trolli

                                                         2/24/85


















                                        1






        1.0) GENERAL

                NETWORK.BAS  outputs  the ac frequency reponse for a user
            described  electronic  circuit.  The circuit  description  is
            prepared  as  an  input  text  file  containing  a  two  line
            specification   for  each  element  in   the   circuit.   The
            specification  of  each element requires the user  to  assign
            node  numbers  to each node in the circuit.  This  method  is
            similar  to  many  commercially  available  circuit  analysis
            programs.

                  When  NETWORK.BAS is run,  it builds a matrix from  the
            user's circuit description file and evaluates the output node
            voltage at each frequency under the assumption that the input
            node has a 1 volt signal with zero phase angle applied to it.

                  At run time the user may specify the  frequencies to be
            calculated  as  either a linearly or  logarithmically  spaced
            interval.  Output  is  sent to the screen by default  but  an
            optional output datafile may be specified at runtime.

                  Models   are   provided  for   Resistors,   Capacitors,
            Inductors,  Bipolar  transistors (current controlled  current
            sources),  Fets  (voltage  controlled  current  sources,  and
            Opamps (voltage controlled voltage sources).





























                                        2





            2.0) ACKNOWLEDGEMENTS

                  Network.bas  is  an adaptation of an  existing  circuit
            analysis  program  to  run on  the  IBM  PC.   The  origional
            article:  "Verify Network Frequency Response With This Simple
            Basic Program",  Werner A. Schnider, EDN magazine, October 5,
            1977,   was  written  for  a Hewlett  Packard  9830A  desktop
            calculator.

                  The  program  was  modified to run on an Apple  II  and
            reappeared  in  the  magazine  as:  "Basic  Program  Performs
            Circuit   Analysis",   Richard  Steincross,   EDN   magazine,
            September 1,  1982. This version expanded the capabilities of
            the  program  by  adding inductors to  the  network  elements
            supported.  It  also  allowed the user to specify  input  and
            output nodes at run time.  After testing this program, I have
            removed  this  feature because it did  not  produce  reliable
            output for a number of simple circuits.





































                                        3





            3.0) REQUIREMENTS

                  NETWORK.BAS  runs  under  IBM or Microsoft  BASIC  (not
            BASICA). It does  require a single disk drive. If your system
            has  enough  memory to let BASIC max out its 64k program  and
            data space limitation, then NETWORK will be able to handle 40
            nodes. If your system has less memory it will be necessary to
            adjust the number of nodes ( Y in line 1200 of the program).

                  Because the program output has been limited to text, it
            can  run  with either the monochrome or  color  adapter.  The
            input  and output formats have purposely been kept simple  to
            allow  most  systems to run the  program.  (Besides,  I  have
            enough  problems making programs print the correct answer let
            alone print it on a jazzed up screen.)








































                                        4






            4.0) RUNNING THE PROGRAM


            4.1) Number the nodes

                  To analyze your circuit, it will be necessary to number
            the nodes on your schematic diagram.  These node numbers will
            be  used to prepare a precise description of the  circuit  so
            that NETWORK can construct the circuits network equations.

                  The  input  node must be node number 1 and  the  output
            node must be the highest node in the circuit.

                  AC  ground is node 0.  The 1 volt input that is applied
            to node number 1 is referenced to node 0.


            4.2) Prepare Input File

                  Prepare   a  text  file  that  contains  a   two   line
            description   for  each  circuit  element  according  to  the
            definitions below. Note that comments may be added after the
            element  type so that the origional reference designations of
            your circuit's schematic may be retained as part of the input
            file.  This should make it easy to go back and forth  between
            your schematic and the input file.

                  Also  comments may be added anywhere in the input  file
            by placing a ";" at the beginning of the line.


             Resistors:

                  R
                  from node, to node, value (in ohms)

                       Example:  A 1000 ohm resistor between nodes 1 and 2.


                       R
                       1,2,1000


             Capacitors:
                  C
                  from  node,  to node,value(in micro farads)

                       Example: A 10 uf capacitor between nodes 3 and 6.

                       C
                       3,6,10



                                        5





             Inductors:

                  L
                  from node, to node, value (in henries)


             Fets:

                  F
                  gate node,  source node,  drain node,  transconductance
                                                           (amps/volt)

                  Example: A common source fet with 10 mmhos transconductance.

                       F
                       2,0,4,.01

             Bipolar Transistors:

                  B
                  base node, emitter node, collector node, beta, b-e resistance
                                                                 (ohms)

                  Example: Emitter follower with beta=100

                       B
                       3,4,0,100,.001

             Op Amps:

                  O
                  + in, - in, + out, - out, gain, output resistance (ohms)

                  Example: Voltage follower.

                       O
                       1,2,2,0,1000000,100


















                                        6





        4.3) RUN THE NETWORK.BAS PROGRAM

                      The  program will prompt for an input filename.  It
            assumes that your circuit desctription is contained in a file
            with a .NET extension.  If you can't remeber the name of  the
            circuit  desctription  file,   hit  the  ENTER  key  and  all
            filenames  with  extensions .NET on the default disk will  be
            listed on the screen.

                      The  program  will  tell you the  number  of  nodes
            actually  found in the circuit description file and tell  you
            which nodes are being used as input and output nodes. At this
            time verify these with your origional schematic to catch  any
            errors   that  you  may  have  had  in  your  input   circuit
            description.

                      The  program  will  now  ask for the  name  of  the
            optional output file that will be used to store the data from
            the program. You can avoid creating the output file by mearly
            hitting the ENTER key.


                  When  the  program asks for the frequency range  to  be
            analyzed,  either a linear increment (a positive number) or a
            number  of logarithmically space points (a  negative  number)
            may be specified.  If the logarithmic spacing is chosen,  the
            number entered is the total number of points to be calculated
            over the entire frequency interval.

                  At the end of the analysis, the program will prompt for
            a  new  frequency range.  If you decline the  opportunity  to
            recaclulate  over  a new range of  frequencies,  the  program
            terminates.


        4.4) Cautions

                 Be  aware that there are some common pitfalls  that  can
            occurr  with  circuit simulation programs of this  type.  One
            that  frequently occurs is that where a dynamically  unstable
            circuit is modeled (your amplifier is really an  oscillator).
            Also  be  sure that there are some resistive elements  in  LC
            circuits   to  prevent  resonances  from  peaking  into   the
            ionosphere. These are only common sense.

                 Always   specify   some   resistance  in   the   bipolar
            transisitor and opamp models to prevent them from blowing the
            program away.







                                        7




        5.0) SAMPLE CIRCUITS

                 Sample  circuit description files have been included  to
            help you get the hang of setting up circuits. These are:

             Sample1.net - A low pass RC filter circuit (1 hz cuttoff)

             Sample1.net - A high pass RL filter circuit (1 hz cuttoff)

             Sample3.net - A  bandpass LC filter circuit  (1 hz center)

             Edntest.net - The test circuit from the origional EDN article












































                                        8




        6.0) COMMENTS AND FEEDBACK

                 I  would appreciate some feedback from anyone  who  uses
            the  program.  I  am planning to improve the program  in  the
            future in the following areas:

             - Provide a more general purpose analysis that lets
               you pick inputs (multiple) and outputs (multiple)
               independant of node numbering.

             - Allow the output of one analysis to be fed into the input
               of the next to get around the memory limitations.

             - Add a plot routine (lin, log and semi log) to the program.
               If anyone has a general purpose routine like this, I'd
               like to hear from you. Most of the public domain stuff is
               junk unfortunately.

             - Run  it  through a compiler.  Right now the  circuits  are
               solved using Cramer's rule which stinks when it comes to
               circuits above about 6 or 7 nodes. In general try to get
               it to run faster.

                                                Bruce  Trolli

                                                Cleveland RBBS
                                                (216-3310510)





























                                        9
-3310510)