Simple diode capacitor circuit help needed.

Thread Starter

Littlekurt39

Joined Sep 14, 2006
2
Hello everyone. I am doing some of my homework in my intro to circuits class and i am stuck on something.

For the circuit attached


I am having troubles getting through t = 0+ (t>0).

Thanks for looking

Kurt
 

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Papabravo

Joined Feb 24, 2006
13,933
e-mail won't work for me at the moment. Maybe one of the moderators can explain why Microsoft Word documents are inaccessible when they are uploaded. I haven't been able to see one,( a .doc file), since the forum software changed.

Edit: If I download the file to my machine, which is risky because these files may contain macros which can damage my machine, I can see it. In the future you should use a less threatening file type.

In the circuit, continuity REQUIRES that value at 0+ be identical to the values at 0-. In both cases we are allowed to make these points infinitesimally close to 0. The derivatives of v and i may be discontinuous, (corners are allowed). Without doing the analysis I can guess that at infinity the diode and the battery will fight each other. The battery tries to charge the capacitor and the diode tries to discharge the capacitor. I'm not sure weather this results in a steady state or if there are small excursions in the vicinity of the steady state. It may depend on the weather the diode is an ideal diode or a real diode.
 

Dave

Joined Nov 17, 2003
6,970
e-mail won't work for me at the moment. Maybe one of the moderators can explain why Microsoft Word documents are inaccessible when they are uploaded. I haven't been able to see one,( a .doc file), since the forum software changed.
This has been a problem for several people, however from my personal experience I can open all file types with one or more web browsers. This leads me to believe that this is an end user setting for either your chosen web browser or MS Word (or other application which is failing to open files on the net). Assuming you are using IE6, then you may wish to go to Control Panel>Security Center>Internet Options>Security. For the Internet Zone, in the security level for this zone click 'Custom Level' and ensure that under the Downloads section that you have both 'File Download' and 'Font Download' enabled.

Let me know if this helps.

Edit: If I download the file to my machine, which is risky because these files may contain macros which can damage my machine, I can see it. In the future you should use a less threatening file type.
You are right to be wary of downloading files that are capable of running macros (e.g. MS Office applications), however be aware that merely opening the file from the web has the same risk associated since you are still launching the file into memory from where the macros can execute. The only difference between downloading and opening a file is that downloading the file puts a peminant copy on your hard drive that can be acccessed later. To be fair, I would be more concerned about the collection of vulnerabilities in MS Word than the capability of macros to cause havoc on your machine.

That said, it is better to convert files to pdf format before uploading, if possible.

Dave
 
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