RE: Too hot 7805

[Mika.Helander@softbit.fi]

There is two ways of frying 78xx regulator (without heatsink) : the voltage
difference from source to (in case of 7805) 5V is so big that even in case
of reasonable load after regulator it gets really hot. I got same kind of
problems when powered my lightning relay controller from 24V to supply 5V
(drives 8 24V relays) and had to put small heatsink to keep it alive.
Another matter is the power consumption of the 2732 which is definitely not
CMOS (=low power) chip!

-Mika

> 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