What's this inductor doin'?

Namely,

Yes, ROM can also be RAM. The two attributes are not mutually exclusive.

"A river flows" is a rather poetic description. If the Army Corps of Engineers installed a flow meter in a river, would they label it "river flow", "water flow", or "rate of flow?"

would

the

Probably not be confused, but one never knows.

The original question scrolled out of my message buffer. I only have some of the replies, including yours.

word

included

You could say "some current exists through ...".

the

I can easily guess what you mean. Perhaps a better way is to say "The current brings/deposits a quantity of electrons ...."

those

off

spring,

and

current

"Charge" is used in electronics as either a noun or a verb. I shun using it as a verb in electronics because it can be confusing. It is surprising how many nubes think that charging a battery or a cap means filling it up with electrical charges so they can be removed and used later. The word "energize" is more descriptive. There is no problem in using "charge" with respect to filling a gas tank or using a credit card. This is because we are not adding/removing "charges" on these items. Furthermore, unlike a cap, we are actually increaing/decreasing their net quantity of gas or credit.

because

to

If

Your hope is probably justified. I was explaining why I thought a cap should be thought of as energized.

Neither, they mill about smartly.

that's

I agree with both sentences above.

Yes, that is more technically correct.

that

Indeed, the charge is imbalanced.

I believe they do, whether they are folded, interleaved, rolled, or bifuracted, they can still be analyzed as a sandwitch with a dielectric filling.

No, the word energize means to imbue energy to something. We can create a electrostaic field in a capacitor, or a electromagnetic field in a coil, or dissipate heat and maybe light by creating a current through a resistor. Either way the circuit is energized.

Yes, and many folks think that R=V/I is Ohm's law, which it is not. Ohm's law refers to the resistive linearity of a material, not the resistance formula. But everyone first thinks of that formula when you say "Ohm's law".

don't

I should have been more descriptive and said "its voltage value goes from ..."

No plates or their equivalent? What then?

Yes, I should have said they repel each other. I was giving the electrons anthropic properties they did not deserve.

the

Only the OP can answer that one.

One of worse descriptive phrases comes from NASA when they refer to their astronauts as "space walking." Everyone knows what they mean, and all can see that they are floating or drifting, not walking. I always wanted to ask NASA what would happen if their tethers separated. Would the astros walk away, or float away from their ship? I liked it better when they referred to that activity as EVA. Walking in space to me means walking on a structure in space wearing sticky boots. Ratch

Because it agreed exactly with Steve's prediction. I think therefore I'm entitled to rely on it in this instance at least.

BTW, Reg. Is there a program on your site that can handle stripline calculations for UHF circuit board inductors?

SPICE has been used for decades in the design of countless products that you undoubtedly use daily. It's an extremely useful and valuable tool, without which many modern designs simply wouldn't be possible.

Roy Lewallen, W7EL

Buggy?? I'm using Multisim (formerly EWB) which has been around longer than most spices and therefore has probably less bugs than the rest put together!

Gotcha, Steve. I won't forget that distinction in a hurrq! It\s amazing after nearly 2 years of studying this subject that I didn't tumble the true meahing of clamping. Duh!

Okay, Steve, I've snipped your explanation about negative voltages as that wasn't quite what I was getting at. I'm familiar with the analogos you used (which I'm sure will help ohters in future via Google). I've done quite a lot of experimentng with opamps using split supplies, hence I don't have a problem envisaging below ground voltages where the supply is say +15V - 0 -15V. The problem I was having was with below ground voltages in a circuit with only one ground and one V+ supply! I'm gojng to have a good think about this before posting back for further clarification. I'm not completly sure that its all down to the cap alone. Mebe the diode has an effect on t producing his sub-ground signal as well?

Steve

It's only impossible to form a reliable conclusion when "experts" disagree if your sole source of knowledge and information is from those "experts". That's a bad spot to be in. There are many sources of information available to help you learn about the topic and come to a more informed opinion. That's the solution to your dilemma -- develop a wider range of sources of information and decrease your dependence on the "experts".

Originally developed at Berkeley, SPICE has been commercialized by a number of companies, one of the most popular being PSpice by MicroSim. It's in very wide use, and has been for decades. Do you think that a couple of generations of engineers would have paid several thousand dollars each for software with a reputation of unreliability?

My own experience includes about 30 years designing a variety of test and measurement equipment for several companies, followed by several years doing electronics design as a consultant. In that time, I and my colleages at Tektronix and other companies used SPICE very often. (In fact, recognizing it value, Tek spent a large amount of money and devoted resources to development of its own internal version of SPICE, which included schematic entry and other features before they were available in outside commercial versions.) It's virtually impossible to design an analog or mixed analog-digital integrated circuit without it, and I and my colleagues found it indispensible for many other projects.

You might compare this with Reg's experience with SPICE, if he'll tell you what it is, and see what brought him to make the unequivocal statement about it which he did. I don't personally think he really believes that it's unreliable, though, but was just making one of his characteristic trolls in order to relieve boredom.

Roy Lewallen, W7EL

Steve Evans wrote:

program.

=========================

There's far too much blind faith placed in computer programs.

Programs can be no better than their authors who are only fallible human beings.

Good programmers may be able to write practically bug-free programs. But their technical knowledge of the subject matter might be no better than the old-wives who write magazine articles and often contribute to these threads.

Without any intended offence, your Multisim program is worthless to me for the purpose of checking or confirming anything. Why? Because I've never even heard of it! Therefore it carries no weight in attempting to convince me of anything.

Your use of the word "probably" is significant. In the absence of knowledge of the probabilities involved I think it inadvertently displays a measure of lack of confidence in the program.

The only way of accumulating confidence in a computer program is to use it and compare results with what you are already aware of as being true. But if what you are already aware of is untrue and so also is the computer (because you both make the same easily-made mistakes) then your own confidence will be improved but the confidence of others (who may think they know better) in what you say will be undermined.

So, on balance, quoting (or misquoting) computers, measuring instruments, magazine and other articles and contributors to this newsgroup is just a lot of hot air and nobody gets anywhere. Reliabilty depends solely on the confidence which can be placed in the writer.

In extreme cases some authors are worshipped as being infallible such as in ARRL and RSGB handbooks, Terman and Kraus (who I have heard of). Name dropping is better not practiced by name-droppers as a means of supporting and reinforcing their technical arguments.

In the end, statements made by newsgroup contributors are made on their own responsibility without the assistance of free adverts of type numbers of particular measuring instruments, names of computer programs which the great majority of readers have never heard of, the 3 gentlemen who pronounced that 120 radials was a magic number but who forgot to measure ground conductivity, and various worshipped authors whose printing errors and misquoted sermons occasionally disagree with each other, etc.

I'll allow mention of Clerk Maxwell but only by people who have read and understood him. And there's very few of them around. ;o)

Well, I've wandered around and probably said too much. I'm unable to swig wine of any sort tonight because I'm on a 7-day course of anti-biotics and it says on the associated leaflet, in capital letters, alcohol is barred.

Here again, Roy I"m confused. You say its indespensible; Reg Edwards says its' unreliable. Who am I to beleive? When the experts disagree, its imposible to form a reliable conculsion.

I can't believe you haven't heard of Multisim, Reg! It used to be Electronics Work Bench and is with little doubt the worst heap of sh*t simulator on the market. One can but hope the OP's got the demo version for nowt or he's spunked a load of cash on SFA. They wanted 4 grand for this hopless crock of sh*t last time I looked!! :-D

Some years back, after retirement, I bought out of curiosity a copy of Electronics Work Bench. It was and still is the only such program I have ever had my hands on. I think it arrived on a collection of floppies.

After a few days curiosity was satisfied. Then I junked it.

All programs have bugs. I only asked why people think it IS reliable.

I am aware of its existence only from the frequent mentions made on newsgroups.

Why do the arguments continue after Spice has arbitrated?

I have no reason to think Roy's opinion of Spice is anything other than true.

But whatever it is, it is not a device intended to be used as a means of instructing learners on the theory of electrical circuits. All programs have many limitations which eventually always become serious and which are UNKNOWN to the user. Very often they are unknown even to the programmer. Limitations should not be allowed to cross over the borders of knowledge. Programs should not be worshipped for always telling the gospel truth. They don't.

For example, a sensible circuit designer invariably checks the output of a program by making a hardware prototype - or several. Why? Because he trusts neither himself nor the program!

Just an explanation to the person who asked:

Reg is one of the few people in the world who have no use for a spice simulator. He writes lots of very good calculation programs and knows electronics like he had a built-in electronics simulator in his brain. He has studied electronics during a long life and knows what he talks about.

For other people though, a spice simulator can be very useful.

Multisim has a very bad reputation because is has a lot of bugs. The best version of EWB is 5.c After that version multisim replaced the central parts of the program and the new program had a lot of problems.

Nobody uses later versions of multisim, so we do not know if they have solved the bugs yet.

EWB 5 is used by beginners, because it has a very good user interface. But even EWB 5 is not regarded as a good spice simulator.

Professionals often like the freeware spice simulator Switchercad3 from Linear Technology.

I use EWB 5.c myself, because it is good enough for my purposes, and it is a lot easier to work with than Switchercad3. But I use Switchercad3 sometimes too, because people in newsgroups often give a circuit in switchercad's text file format.

Another advantage for EWB is that it has been around a while, so there are many add-ons to the program, like a converter from EWB circuit to an Eagle layout (Eagle is a freeware layout program for circuit boards). Translation programs from ewb to standard netlist is also available.

After multisim changed the program there was a big wave of protests among the EWB users and buyers. New buyers demanded to get a copy of the old working program when they bought the new version, and Multisim accepted that and delivered a EWB version 5c for free, on demand, to all buyers of the new program.

I don't know if they still do.

Question - what is the internal modelling technique used by these various programs, and can we produce our own package?

Is it based upon successive delta-time increments, and if so, what is the increment? What prompted the last question is an attempt I made to create a sine-wave generator using the identity that sin dTheta = dTheta, but I had to go for an _extremely_ small value of dTheta (ISTR 10^ -18) before getting anything like a decent sine wave, and even that degenerated after a few cycles.

So, these circuit simulators - what is their underly> > Some years back, after retirement, I bought out of curiosity a copy of

Most of them (exceptions being the harmonic balance types for RF) use the old Berkeley Spice engine developed by the good folks at the eponymous university. The simulation package authors just adapt the engine with their own preferences WRT to features, GUI, gimmicks etc. So yeah, you can certainly come up with your own flavor of Spice just by adapting the basic Berkeley engine to your tastes. It's highly unlikely to be worth the effort, though. There's already a spice out there for everyone - if you can find the right one for you.

I'm not interested in someone else's engine - that's not the way of the _REAL_ Radio Ham

It is _ALWAYS_ worth the effort to do things for yourself - that is the essence of _REAL_ Ham Radio - it is the CBer and the CBer-Masquerading-As-A-Radio-Ham who buy things off-the -shelf!

It's been the case in Britland for many years now, that if you want info to build modern gear, then buy the ARRL handbooks. OTOH, if you want a mediocre book that is many years out of date and seems to owe more to self-congratulation than it does to technical excellence, then go for the RSCB offering. Odd, really, when you consider that the RSCB is a publishing corporation.

In 1970 I bought the latest issue RSGB Handbook, obviously a decade before the transistors were being discovered in England, and several decades before the spectrum analyser were applied over there. So after a week I managed to find another person to keep the book, not sure if he paid for the rubbish

You owe me a keyboard to replace the one that just died under three quarts of drool.