resetting a filter

Who in hell would *want* a fast 555?

You didn't build your company, either. ;-)

That's a special case of the question "Who in hell would *want* a

Had a little help from my friends.

I can understand some uses for a 555, particularly tasks that operate at relatively glacial speeds. I can envision *none* that would require high speed.

...and, of course, government. ;-)

What better friend could you ask for?

I don't have any trouble with CMOS, but I run into _many_ young bucks who don't understand that it's not always a one-to-one substitution getting from bipolar to CMOS. Of course some of them have a good excuse... they've never seen bipolar before. ...Jim Thompson

I don't think Larkin's posted circuit "We built it and it oscillated and we fixed it" shows the "fix" if it actually was fixed. ...Jim Thompson

I was just looking at Camenzind's book again, and he has a pretty complete discussion of that in Section 11-6. The extra speed comes from not needing Darlingtons on the comparator inputs. Of course the Intersil 7555 is only a few times faster than the NE555.

The last time I used a 555 was in about 1994, where I used it to drive a bunch of infrared LEDs in an ultralow cost head tracker. Detection used a quad op amp and three MC1496s for lock-in detection with about 46 dB of gain, plus a Philips 87C552 micro to do data acq and serial communications.

The head tracking function uses six small solar cells plus a shadow mask cut in the lid of the box to get X, Y, and Z position. Ultra ultra cheap and worked great.

Cheers

Phil Hobbs

AND CMOS doesn't store charge and have a recovery time.

Feature size on the antique is HUGE. I've made PVT-stable R/C oscillators on 0.18um CMOS at 100MHz.

...Jim Thompson

No, of course not. But things with resistors in their emitters tend to RF oscillate, including when driven by opamps.

I was playing with the air flow sensor idea a couple of weeks ago. The circuit is grounded-base with a resistor from emitter to -5. I varied positive Vc to vary power dissipation at constant collector current. A

It's a hazard. And if you buy a generic 2Nxxxx, you can't count on what you'll get, how big the die will be, what the Ft might actually be, so some circuits might oscillate, some not.

Not according to O Bummer.

ion.

xes

The usual right-wing nit-wittery. What Obama actually said was that your business depended on roads, bridges and other infra structure, and you didn't build that, but Karl Rove is alive and well and so there's been a little selective quotation going on.

Happily, we don't have to worry about it. Romney has chosen his Sarah Palin, and while it may guarantee him loads of campaign contributions, the previously undecided voters aren't going to put Paul Ryan anywhere where he can get at Medicare.

As any right-winger will tell you, responsible people would prefer to die rather than exploit their neighbours by relying on socialised medicine, but few people are actually that "responsible" or - as the rest of the world sees it - that far out of touch with reality.

-- Bill Sloman, Nijmegen

I didn't see any of them as any better than this, and most were much more expensive to implement.

The transistor is, essentially, the former. The latter isn't very practical on a VME board.

Actually, from decades of experience.

Yoy won't see it in Spice, because it's local to the transistors, not a loop oscillation. It's a big enough risk that a base resistor is a good investment.

Make him read a few thousand usenet postings from Sloman. He will have no respect after that. :)

But I want creativity from him, not fatheaded boasting and insults.

Sloman has been working on a single oscillator circuit for years. P is stunningly fast; we bring up a requirement in an engineering meeting, and it turns out he's done it already.

That's Michael Terrell's experience - he doesn't known much, and can't be expected to respect what he doesn't understand

You can supply all the fat-headed boasting needed, and all the insults, and still have plenty left for sci.electronics.design.

For want of something better to do, and not with any great application.

That doesn't make him stunning fast, it makes you stunningly slow. If you don't really understand what you are asking him to do, and he does, he is going to give you what you need rather than what you asked for, usually before you get around to realising that you need it.

I had a bit of trouble with that with some of my managers in the U.K.

- they obviously weren't as clever as you think you are, since nobody could be that clever - and they tended to suffer from an imperfect grasp of the detailed implications of what they were asking for.

-- Bill Sloman, Nijmegen

Now that the creator of the 555 AND Phyllis Diller are both dead, he should be able to start using his left hand again. Maybe he'll finally get through it.

Bahahahaha!