Franc Zabkar wrote:

On Thu, 30 Apr 2009 19:44:02 +1000, Bob Larter
put finger to keyboard and composed:

http://zekfrivolous.com/misc/twinalert.JPG

It looks like it's monitoring the temperature (there's a thermistor on
the bottom right of the PCB). I notice that it has a local regulator,
which I'd be guessing is a 7805 that's shorted out.

The pinout for a 7805, from top to bottom, is "In Gnd Out". This
doesn't fit with the "+12V Gnd Gnd +5V" pinout of a drive connector.
In any case why would you need a local +5V regulator when the incoming
supply already provides +5V? If for some reason you did need a +5V
regulator, then wouldn't a 78L05 be adequate for this circuit?

That heatinked device seems rather odd, not least the way it's mounted with
bent leads.

Graham