What's the best bypass caps?

[Active8]

I think that's regarded as a very masculine trait. Wimmin are supposed
to go for guys like that as they're like alpha male-types and
therefore more likely to dominate other males, win food and such like.
Well, that's wimmin for you. :-|

i realize it's a masculine trait, but only on a real man.

Does anyone?

i've talked to some who like him. they spent most of their life in front
of the stoopid box and would probably swallow anything. ask them if they
saw something on the news and the answer is invariably, "huh?" ask them
if the saw martin or oprah and they'll talk about it until the run out
of breeath and someone changes the subject to WWF wrestling or something
else requiring a 2 digit IQ.

mike

 

[John Devereux]

I recall just the opposite, that the bipolar version crowbars the
supply during switching. Let's find out..

This Philips datsheet for the (bipolar) NE555 seems to confirm that:

http://www.web-ee.com/primers/files/555AN.pdf

Due to the nature of the output structure, a high power totem-pole
design, the output of the timer can exhibit large current spikes on
the supply line. Bypassing is necessary to eliminate this phenomenon.
A capacitor across the VCC and ground, directly across the device, is
necessary and ideal. The size of a capacitor will depend on the
specific application. Values of capacitance from 0.01uF to 10uF are
not uncommon, but note that the bypass capacitor would be as close to
the device as physically possible.

And this National data sheet for a CMOS version:

http://cache.national.com/ds/LM/LMC555.pdf

The LMC555 offers the same capability of generating accurate time
delays and frequencies as the LM555 but with much lower power
dissipation and supply current spikes.

Thanks for looking it up; sheer lazyness on my part I'm afraid.

I haven't used a 555 for at least 15 years... Strange, I could have
sworn it was the CMOS version that had the spikes!

 

[Paul Burridge]

Thanks for looking it up; sheer lazyness on my part I'm afraid.

I haven't used a 555 for at least 15 years... Strange, I could have
sworn it was the CMOS version that had the spikes!

What's different about the NE555, then?

 

[John Devereux]

What's different about the NE555, then?

The NE555 and LM555 are "bipolar", i.e. made from npn & pnp bipolar
junction transistors. The LMC555 is CMOS, i.e. the output stage is
made from MOSFETS.

 

[~^Johnny^~]

The whole ten layer board has over 400 decoupling caps of various
denominations. Manually routed using Orcad PCB386+

FOR THE LOVE OF MIKE! Crazy...
--
-john


~~~~~~~~
Maybe I should ask Radio Shack. They claim they've got answers;
but frankly, if Radio Shack were our provider, we'd _really_ be in
trouble now, wouldn't we?
~~~~~~~~

 

[Dave VanHorn]

"~^Johnny^~"

FOR THE LOVE OF MIKE! Crazy...

I take it you haven't tried Cadence's Layout product. The new windows
version of Orcad.
I worked with it for a few months, and ran screaming back to PCB386+

Check out the dos_orcad group on Yahoo.

The autorouter in Layout has many more options than it's predecessor, way
more things to tweak, and it's only a bit less useful than the original.