RE: Electronics Question...

["Dave McLaughlin" <dave@xxxxxxx>]

Hi Ian,

What other devices are in your design? The 78L05 is only capable of
supplying 100mA max current and above this the voltage starts to drop as it
heats up.

I normally see this when using a few LED's in the circuit but not knowing
your design it does not help. There is a higher rated device in the same
package available from the likes of Farnell and RS but I can't remember off
hand what the part number is. If you need it give me a shout and I'll look
it up.

Regards
Dave...

-----Original Message-----
From: Ian Lowe [mailto:ian@xxxxxxx]
Sent: 26 December 2002 18:55
To: ukha_d@xxxxxxx
Subject: [ukha_d] Electronics Question...



Been debugging one of the wackiest problems I have ever seen over the
festivities, where writing a value to EEPROM failed (although the rest of
the circuit worked perfectly) After some helpful souls trying the code out
for me, I figured out that the problem was power related. :

I'm using a 78L05 to derive a 5V supply from a 12V feed, and only getting
4.7 Volts (!!) which is great, right up until the PIC tries to do something
juice intensive, at which point, it fails..

I have tried dropping a 220u cap across the 5v-0v feed, thinking that would
give a little reserve for intensive ops, but no joy..

I don't want to bore the bits off of the list at large, so can anyone who
wouldn't mind giving a point in the right direction drop me a mail?

Ta muchly, and I hope that yesterday's dinner has largely settled by now ;)

Ian.

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