%  Step Response Script
%  This script will plot the step respose of a low-pass RC filter
%  using the parameters defined below.  The time axis will be plotted
%  in terms of time constants (i.e. normalized by RC).
%
%  Written by Kevin D. Donohue 9-7-2004 (donohue@engr.uky.edu)

R = 1000;  %  Resistance value
C = 1e-6;   %  Capacitor value
A = 10;  % Voltage (max amplitude) of input step
tc = R*C; % Compute circuits time constant
%  Time axis Limits in terms of time constants
num_o_tc = 5;  % Number of time constants for length of time axis
sample_int = .01;  %  time inteval as a fraction of the time constant
t = [0 : tc*sample_int : num_o_tc*tc];  % Create time axis from 0
vc = A*(1-exp(-t/tc));   % Compute step response
figure   %  Open new figure window put plot 
plot(t/tc, vc);    %  Normalize time axis by time constant and plot response
xlabel('Time in Number of Time Constants')  %  Label x-axis
ylabel('Amplitude')  %  Label y-axis