[sdiy] Debounce & hold +5v signal for 1/10 seconds

[Scott Gravenhorst]

"Paul Maddox" <P.Maddox at signal.QinetiQ.com> wrote:
>Andreas/Scott,
>
>> The app note I have for the 555 timer indicates that it is
>nonretriggerable
>> as a one shot, so this part would fit your needs.
>
>Only comment on this is use decoupling, the 55 makes a compete mess of the
>supply lines without it.

This is much more true of the bipolar 555 than the 7555 CMOS part.

>From the datasheet I have:

"The ICM7555/6 produces supply current spikes of only 2ma to 3ma instead of
300ma to 400ma and supply decoupling is normally not necessary"

This isn't to say one should not decouple, but the 7555 is just better for
low current applications such as the one indicated in this thread.  300 to
400 milliamps of current spike can be hard to get rid of (this is apparent
in the stock FatMan, and you can see the bizzare way John Simonton had to
deal with this - and the original method wasn't all that effective).


>and don't get it wrong, only time I blew up a chip, I managed to make a
>555 explode, big hole in the middle of the chip afterwards and no sign of
>the rest it anywhere :-)

How the heck did you manage this?  For me, they work like they're made of rocks!


---------------------------------------------------------
- Where merit is not rewarded, excellence fades.
- Hydrogen is pointless without solar.
- What good are laws that only lawyers understand?
- The media's credibility should always be questioned.
- The only good terrorist is a dead terrorist.
- Governments do nothing well, save collect taxes.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.gte.net/res0658s/fatman/
-- NonFatMan: home1.gte.net/res0658s/electronics/
-- Autodidactic Master of Arcane and Hidden Knowledge.