>   My question is that, what about the current amount of 
> 30VDC, I know that pic16f84 needs low current. But to feed 
> all the HUBs the suppy should provide much more current.  I 
> know that 7805 can provide up to 1A. Since their a loos on 
> line also, If supply provide much current, for instance 0.5A, 
> i.e., 30V/1A.  Can the 7805 output damage the pics16f628s.  

I hope you feed the 30V to all 7805's, not the output of one to the
input of the next.

You can calculate the total current as N * ( 5V current + 7805 '0 load'
current). Check your datasheet (note: 7805 specs can vary!).

The 7805 output can not harm the PIC, unless you hve funny things on the
7805 input. Which might be caused by your (long?) cables.

Why 7805? If the 5V current is low an 78L05 might be more suited.

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: www.voti.nl/hvu
 
 

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