9 Dec
2006
9 Dec
'06
3:42 p.m.
On Dec 9, 2006, at 11:45 AM, Chuck Guzis wrote:
I can see that being the case when you need multiple related pulse
trains or something like that...but to replace a single 555, I find
this very difficult to believe. I've designed both into commercial
products in the last few years...Sure, PICs are super cheap, but 555s
in thousand-unit quantities cost less than a dime. As for the
discrete components...Assuming you're running the PIC in internal
oscillator mode (which saves you a crystal and two capacitors), you
need a pullup resistor to MCLR, while a typical 555 oscillator
circuit needs one or two resistors and a capacitor...so a capacitor
and possible additional resistor. Add in the step of having to
program the PIC (and maintain the codebase, documentation, etc)...no
way.
It seems to me that many of these types of attitudes stem from the
"if it's old, it's bad, and if it's not new, it's old" mentality
that
has been adopted by the obedient mass of consumers.
-Dave
--
Dave McGuire
Cape Coral, FL
Actually My
first draft was a 555. By the time all the
requirements were met,
the component count had gotten out of hand. 7420,555,7438,handfull
of descretes... a single 20 pin package a crystal and a transistor
didn't
seem like overkill.
And it would handle the creeping feature bloat My projects suffer
from ;^)
I happened to mention this to a customer yesterday who sells
computerized scales and the like. His comment was that a PIC was
very competitive with a 555, when one considered the external
discrete component count and glue--although he admitted that a number
of his products still use lots of 555s.