Re: Too hot 7805

["Peter D. Hipson" <mail@darkstar.mv.com>]

The amount of heat disappated is voltage drop (input voltage - output
voltage) times current. If you were drawing .5 amp (500 MA), had an input
voltage of 14V, and output voltage of 5 volts, then the 7805 would
disappate 4.5 watts (more than the design spec, i belive) and would get HOT
fast. Check the current draw first, make sure that it is not too high. Use
a heat sink. A shunt transistor may be the best fix, or a regulator that is
able to handle higher currents. REgardless a heat sink would probably be a
good idea.

At 11:22 PM 1/27/2000 -0500, you wrote:
>I'm running a 7805, to supply 5v to a 2732, and 2 74LC 161s, all the load is
>a LED with a 1K inline resistor.
>   The 7805 is really hot after just seconds, I've checked my wiring a
>jillion times, ans still that way.
>  Can this 3 chips be drawing that much current?.
>Grumpy
>  This is for the ecm bench, and when "proven" will be ready for prime time
>(FTP).
>
>----------------------------------------------------------------------------
>To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
>in the body of a message (not the subject) to majordomo@lists.diy-efi.org
>
>
>
Thanks, 
        Peter Hipson (founder, NEHOG)
        1995 White NA Hummer Wagon
----------------------------------------------------------------------------
To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
in the body of a message (not the subject) to majordomo@lists.diy-efi.org