generator

[lacy]

The first circuit is obvious to me. Take your pin 3 connection fro the timer and move it from VSS to CP0 (pin 14) on the 4017. Place a VSS source on the scehmatic and tie that to the VSS pin on the 4017.  Try that for the first schematic and let me know the results.

For the second on I would have to plug that into the simulator and check it. I will have to do that later today and it may take me a while to get back with you on that one.

Just so you know you can post your actual files that are created with Multisim to this forum. Just save your schematic to your hard drive and then below the post window there is a box that says "Attachment" Just click on the browse button beside it and goto to the location that you saved your Multisim file highlight it and click open in the browser box. This will put the file into the little box and when you press "submit" the post as well as the file will put up on the forum. In other words, post the Multsim file in the same manner you post the

[lacy]

Sorry about the multple postings. I have notified the moderators about this to see if it is a forum problem or something I am doing causing this.

[Lodin]

Hello ngogketrao

maybe these data sheets will give you some new ideas...

http://ece.colorado.edu/~mcclurel/sn74ls138rev5.pdf

http://iul.eng.fiu.edu/Teaching/Logic/SpecSheets/74LS151.PDF

http://www.fairchildsemi.com/ds/CD/CD4017BC.pdf

regards,

Lodin

[lacy]

Thanks Lodin for the information that you provided. This should help him in these circuits. It may be better for him to take these datasheets and use them to find the probelm in his circuit than it would be for me to give him the solution. I always say that the best way to learn is to screw something up, figure out how you screwed it up, and then fix it yourself. I will let him look at these and try to see if he can troubleshoot his own circuit. If he still has problems then he can make another post and I will render what assisatance that I can at that time. (I hope this doesn't sound cruel,  but in order to design a circuit you must also learn how to troubleshoot it when it doesn't work.)

[ngogketrao]

thanks for your datasheets, it helps to set some parameters. and by the way your english is not a problem,we are not here to learn languages, but instead technology.
  take care!

[ngogketrao]

   hi
  I just wanted to tell you that i got the second circuit working ( basic home security system) , so you don't have to work on it now. for the first one,i did like you said but it didn't work as expected. i am still trying to find what's wrong. I also wanted to add that i studied electronics but we never had any software practice,i am doing this on my own because i think it will be helpful for me. so,please understand me if sometimes i ask some questions that you may find obvious.

    thanks

[Lodin]

Hello ngogketrao

good to hear, that your second circuit is know working.

To help you at the first circuit, please post your actual version of your circuit so we can take a look on it.

(I have nearly no knowledge of simulating these circuits. "Only" by building them in reality )

best regards,

Lodin

[ngogketrao]

hi !
  i attached to this post the schematics of the LED sequencer. i am still working on understanding what's wrong with it.
   thanks

[Lodin]

Hello ngogketrao

this bug is a little bit tricky and shows the difference between theory (simulation) and reality.

The pulse width of your timer is much to short. I think, in reality it would not work. But in the simulator you can see a peak on the oszilloscope. This peak ist to small for the 4017.

You have to add a resistor for increasing the discharging time of C1.

regards,

Lodin

[lacy]

Your configuration on your Timer is incorrect. You have to have 2 resistors one tied between pin 7 and +V and a second resistor between pin 7 and and pin 2 and Pin 6 which are tied together. This is the only way in reality that a 555 timer will work in astable mode as Lodin pointed out in his post The configuration you have now is for mono-stable mode with the exception that pin 2 isn't tied to pin 6 and 7. Pin 2 is left "open" to a negative going signal in order to intiate the output pulse.

I am going to post your circuit with the changes I made. The resistors I selected was not based upon any particular frequency. I selected 2 resistors that I thought would show the circuit working and the changes fairly fast for you to be able to see the LED changing. You will have to calculate the resistor and capacitor value if you desire a particular frequency. I added comment markers to the thins I changed.

I hope this helps.