555 timer plots in matlab

Hi guys !

I want to implement the formulas for vo and vc for a 555 astable multivibrator circuit. I wrote the formulas for vc but it doesn't work. If anyone could help me, I would be very pleased.

function voplot_Callback(hObject, eventdata, handles)
% hObject    handle to voplot (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% plot Vo
ra = str2num(get(handles.edit1,'string'));
rb = str2num(get(handles.edit2,'string'));
c = str2num(get(handles.edit3,'string'))/1000000;
voh = str2num(get(handles.edit5,'string'));
vol = str2num(get(handles.edit6,'string'));

tc = 0.693*(ra+rb)*c;
td = 0.693*rb*c;
t = 0.693*(ra+(2*rb))*c;
d = (tc/t)*100; % duty cycle
f=1.45/((ra+2*rb)*c); % frequency
%Vi=0; %Vi should vary 
%Vf=10; %Vf should vary


if f>100
    p=0:1:200000;
    out=2.5*square(2*pi*f*p,d)+2.5;
    %VCcha = 10^(1-exp(-p./(ra+rb)*c)); %Vc charge
    figure(1); 
   plot(p,out)
    
else
   p=0:0.0001:5;
   out=2.5*square(2*pi*f*p,d)+2.5;
  % VCdis =0*exp(-p/rb*c); %Vc discharge
   figure(1);
 
   plot(p,out)
end
%subplot(2,1,1); plot(out)
%subplot(2,1,2); plot(VCcha)

ylim([0 6])
xlabel('Time(s)')
ylabel('Amplitude(V)')
title('Waveform of 555 Timer as an Astable Multivibrator')

[Cris LaPierre]

What doesn't work about it? All we have to look at is the callback function.

Is there a particular error message you are getting? What are your edit field strings (ra, rb, c, voh, vol)?

[Cris LaPierre]

Using the values shared in this page for a 555 electronic metronome, your code appears to work. I put in the values for 180bpm (3/sec) and got this plot.

I therefore suspect your issue has more to do with making this work in a gui.

[Vlad Hornai]

Hi Cris LaPierre,

Vo works, but I am trying to plot Vc, which is over the capacitor. Also, for Vo the amplitude should be between voh and vol. I changed the parameter from ylim with voh and vol, but still i don't get the good result.

I should obtain this.Vo works somehow, but the problem is I don't know how to plot Vc. As you see in my code, I put in comment the equation for Vc which are exponential because the capactior charges and discharges. If you could help me with this, I would be very grateful because it is for a project for school and this is the hardest part form the project so far.

Thanks.

Answer 1

[Mohan singh]

bro if you are done plzz help me to solve this