[sdiy] filter cap needed?

[db]

At 3/24/2009 08:59 PM, Colin Hinz wrote:
>On Mon, 23 Mar 2009, db wrote:
>
>>I'm sure it's a good idea to have the cap...
>>But, I already fully built my device and closed it up without a cap, and 
>>don't want to get back into it unless it's semi-important..  :)
>
>One of my first tasks as a rookie EE (lo those many years ago) was
>to troubleshoot a microcontroller board which had strangely gone
>insane. It turned out that the 7805 regulator (lacking the recommended
>bypass caps) was oscillating between 3V and 7V. Looked OK when checked
>with a DVM, too -- I had to get wise with a scope, instead.
>"But it worked fine on the bench," the designer wailed.
>
>YMMV, of course. If it's gonna fail, though, it'll probably fail under
>the least desireable circumstances. You'll never say to yourself, "Boy,
>I'm glad I opened it up and put the cap in," but you sure might be
>saying, "Argh! I should have corrected that before I went on tour."


I guess I've now been convinced to do it. :)

Am I correct in that it just needs a .1uf  from 5v to gnd?


dennis.barton:skylab2000[socal]