Lynx {Glenn Jones} wrote:
>
> Ive never smoked a micro, but i once hooked a 7805 in backwards and then
> after smelling the heat i unplugged the supply and went touching compnents
> to find what was up. Ouch! i had a scar in the shape of a TO-220 case on
> my thumb for a week :(

There is a paint based on liquid crystal that change the color upon temperature,
I know someone that painted all the vital components (IC's, Regulators, Power Sw
itchings...) that he uses on the protoboards/prototypes, so he can identify very
 quickly any change
in power consume (and dissipation) on those components, earlier than it can star
t to cause damage... using "nose to touch" and "fingers to smell" (:) is not as
fast as this
solution...  They also sell it in small stripes, so you can glue over the chip.

Why it was not available 20 yrs ago, when I used to calibrate the RF final of tr
ansistored Motorola VHF radio transmitters... fried lots of $40 transistors... b
ecause it was
overtemp for more than a minute.

If somebody is interested in that paint, I can try and find out the info, so you
 can protect the PIC and avoid to have the Microchip logo thermo stamped on your
 nose for a month.

Chameleon paint anyone?

Wagner Lipnharski
UST Research Inc
http://ustr.net