Re: Simple Count down Timer Project! New post!

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But it can reveal an error where a correct symbol or footprint is wired up incorrectly. This does depend on having a computer-aided design environment where the schematic that one looks at and edits is the source of the netlist that drives the simulation engine, not to mention the printed circuit layout package.

Since such design environments usually come with a library of symbols and foot-prints (never complete, of course) anyboody who is using that library tests the sysmbols and footprints wherever they use them, so faulty symbols and footprints do tend end up been corrected pretty rapidly.

Obviously not stupid enough to think - or fail to think - as badly as you do.

-- Bill Sloman, Nijmegen

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Try that with your favorite simulator, dummy. To make such a simulator useful you would need a model for *every* component, something which is not often possible.

Clueless.

You're just stupid as dirt - somewhere around DimBulb stupid.

Respect has to be earned, daily.

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It was certainly possible with the computer-aided design systems that I worked with - we wrote quite a few of the models ourselves. I was never allowed to waste my "valuable" time actually writing the models, but I talked to the people whose hourly rates were low enough that they were allowed to do this, and the models - for the parts we were using - weren't all that complicated.

Presumably you are using bizarre programmable parts or even more bizarre application-specific circuits that you don't under well enough to be able to let you create models - or maybe you are just too stupid to realise that it is possible. The rest of the world seems to expect

- and get - models of the parts they can buy.

So you work in some kind of industrial slum, where the components libraries are hopelessy out of date, and the people who work with them are too depressed by the environemnt to even think about cleaning out the Augean stables.

The sort of place where you'd fit right in as an employee.

=A0It

You do depend on your comforting delusions. It would be hard for you to admit that your workplace is equipped with the kind of software tools that never really worked, and staffed by the kind of gormless nit-wit who will put up with hopelessly inadequate equipment, because they are too stupid to know better.

-- Bill Sloman, Nijmegen

How much respect do you earn by fixing ancient computers? I'm not contemplating going into the business - around here everybody buys new computers because the old ones are obsolete long beofre they wear out

- just simply curious.

-- Bill Sloman, Nijmegen

Immense. He donates them to those who can't afford to buy, and he does the work despite physical adversity.

Ed

solution.

There's an existence proof. 555s work fine for some things, but aren't the most elegant solution to very many. I agree entirely.

If you'd used that paragraph during the CD4020 flame war, you'd have made a useful contribution.

In that 2000 exchange that John exhumed, there was somebody pleading with you not to quit posting because you were one of the few people improving the SNR of the group. I admit being surprised to read that. Why not do it again? You obviously can.

Right, the point is whether they do a good job, within the budget, and remain available for the life of the product. In the last year or two, there's been a cascade of very nice JFET op amps that run on +-15V supplies. Before that, the best medium-speed op amp for low-level TIAs was the LF357, circa 1973. National discontinued them in about 2006, but fortunately some nice TI parts came along. (The OPA657 is not the one I have in mind, though TI touts them very hard--they're actually not very good for that use on account of their horrible input capacitance.)

Probably so. On the other hand, if it works okay and costs less money, that's good engineering IMO.

Cheers

Phil Hobbs

solution.

Good engineering is doing something for six pence (nickel) that any idiot can do for a pound (dollar).

My favourite thing is to do something amazing with almost no apparatus at all. Sometimes that requires a mildly generous definition of 'amazing'. ;)

Cheers

Phil Hobbs

Thanks, Ed. The computers are at least XP before they are refurbished these days. To someone with nothing, it isn't ancient like Sloman's attitude.

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The Australian version was doing something for a quid that any fool can do for two quid.

It captures part one of the skills. One of my bosses commended a colleague by saying that something he'd fixed stayed fixed. A lot of the stuff that didn't stay fixed had been designed around componets that had gone obsolete, but that wasn't what that particular boss had in mind.

Engineering involves paying attention to a lot of different potential problems, and concentrating on any one aspect of the job can distract you from paying adequate attention to all the other potential sources of disaster.

-- Bill Sloman, Nijmegen

Sloman'sattitude.

The Microsoft XP operating system is picky about the hardware that it runs on. Linux is more flexible.

-- Bill Sloman, Nijmegen

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I don't think so. The 4020 is representatiative of the dark side of the CMOS story, where RCA released several rather idiosyncratic ripple counters obviously designed for rather specific applications. They were sort of handy in specific applications, at the time - because CMOS was low power (unless you clocked it fast) you could squeeze more bistables into a CMOS package than you could into a TTL package, and I exploited that - at the the time - just like everybody else. Things have moved on a bit since then.

Back then I was actively involved in circuit design. The relevant bits of my brain do seem to be atrophying for lack of use.

-- Bill Sloman, Nijmegen

ey,

There was just this thread on a physics listserver about chaos. A signal generator drives a diode through a ~33mH inductor, hang a 'scope probe across the diode. At ~100mV input level find the resonance. ~100kHz. Then crank up the signal level. I'd never heard of this before, References from the 80's

George H.

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How about volunteering at some local College/University. Maybe after a few months you can find someone who can pay you. Get your brain back in the game!

George H.

Can you give us some more precise reference? I'm interested.

Thanks, Jeroen Belleman

ard

Sure here's the post. Two references are at the bottom. I was going to post the location of the list server if you wanted to sign up or read the whole thread. But then I thought perhaps I'd better not. But drop me an email and I'll give you the details.

George H.

Simplest I know is as follows:

1. Get a 1N4001 diode and a 25 mH inductor.
2. Wire them in series, and connect them to a sine wave oscillator of

1. Using very small amplitude (about .1 V pp), look at the voltage across the diode with a scope.
2. Tune the oscillator to find the resonance when the amplitude is too small to forward bias the diode. I recall this was about 40 kHz.
3. Slowly raise the amplitude. The scope waveform will change from a sine-ish wave to the typical half-wave rectifier picture.
4. Keep raising the amplitude and the peak heights will undergo successive bufurcations, and finally become chaotic.
5. With some effort, you can locate "windows" in amplitude space where the peak height sequence is periodic.

See, in particular, Rollins and Hunt, Phys. Rev. Lett. vol 49, 1295 (1982), and Buskirk and Jeffries, Phys. Rev. A (1985). (These old references come from my undergraduate thesis, done when the articles were relatively current.)

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When I first moved to the Netherlands I worked - part time - for the Technische Zaken (basically the science faculty workshops) of Nijmegen University (now the Radboud University) and I volunteered my services to them again shortly after I turned 65. They made interested noises at the time, but nothing ever came of it.

We are busy moving house at the moment, and will be for the next month or so, so I'm not going to re-volunteer in the immediate future.

-- Bill Sloman, Nijmegen

I don't think so. The 4020 is representatiative of the dark side of the CMOS story, where RCA released several rather idiosyncratic ripple counters obviously designed for rather specific applications. They were sort of handy in specific applications, at the time - because CMOS was low power (unless you clocked it fast) you could squeeze more bistables into a CMOS package than you could into a TTL package, and I exploited that - at the the time - just like everybody else. Things have moved on a bit since then.

Back then I was actively involved in circuit design. The relevant bits of my brain do seem to be atrophying for lack of use.

-- Bill Sloman, Nijmegen

And what's left of the relevant bits of your brain are being eroded by your steadfast preaching of global warming hogwash. You are the perfect example of an educated idiot. Lots of horsepower, but unable to pull the load.