Burned up my first chip!

Joe Boucher BoucherJC at lmtas.lmco.com
Mon Jan 26 15:23:22 GMT 1998


I was playing around in the garage Sunday before THE GAME setting up a
power supply from an old modem to test some of the circuits you guys and
girls have come up with.  I was curious about a 7805 votage regulator I
bought at Rat Shack.  The back of the card said the input voltage was 35
volts.  I thought that probably meant max voltage so I hooked up a 12
volt power supply to it.  I was getting 5 volts out of it when it
started smelling funny and a small spot on the chip started bubbling.

Ooops.

I think I shorted two of the leads coming out of the chip with the
voltmeter probes.  1) Did that do it? 2) Inputing 12 volts didn't do it,
did it?  3) Did having no load do it?  4) Does it need a heat sink which
is why the back side was nice and shiney?

I found a store near me that sells 6000 types of chips and surplus parts
for a lot less than Rat Shack.  But the hours are inconvenient and the
owner is a jerk.  Can't have everything.

Joe Boucher
'70 RS/SS Camaro  '81 TBI Suburban



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