Senior EE

[JC1]

Good place to work

Hi Carl,

Sounds like Maxim is up to speed on their Analog Engineers, good place to work.

JC

[A SARGE LAST HONOR]

spice

Hi Wirechief,

Gee, looks like EW is now multisim, don't know if you can still get the old cheap version anymore. Look around i guess.

However, they got a student version of CircuitMaker which I like CM alot better. Also should get Pspice demo program, if still can.

don't worry about parts limits much, you will find it wise to just do pieces of your circuits and NOT try to model entire big circuits as this is slow. blah blah

Here's some links.

http://www.aboutspice.com/details.php?ID=219

http://www.aboutspice.com/index.php?...3722854f777c9e

http://www.circuitmaker.com/products/index.html

http://www.circuitmaker.com/education/index.html

JC

[A SARGE LAST HONOR]

pspice

Looks like the layouts guys bought up all the
circuit simulation software guys. Messed things up a bit.

Here is pspice demo. Designed alot with demo programs long ago.

http://www.ecircuitcenter.com/demos.htm

Topspice is another one, have not tried demo or real program.

JC

[A SARGE LAST HONOR]

anagrams

That anagram thing works in reverse also.

list gets long if not tell it how many words.

try two.

JC

[A SARGE LAST HONOR]

More Delay

So anybody figure out WHY non-linear group delay
causes noise to go up? Besides peak in group delay
or overshoot ringing whatever. Gut feel?

Audio buffs (Eric), more info.

A recent audiophile magazine review of a 3-way speaker, with response similar to (e) above claimed: "... The step response indicates that the tweeter and midrange unit are connected with positive acoustic polarity (the sharp up/down spike at 0 ms and the lazier triangle 0.4 ms later), while the woofer is connected with negative polarity (the broad, negative-going hump centered between 1.5 and 2.5 ms). The actual drive-unit polarity doesn't matter except when it comes to waveform preservation -- and the jury is out on that subject."
More understanding of the subject matter is obviously needed.

The phase of a speaker's frequency response has to change linearly with frequency in order to preserve waveform fidelity. This is equivalent to saying, the group delay has to be constant (f).

f the allpass Q0 is significantly higher, like Q0 = 2.5, then the phase distortion does become audible. In the case of the 100 Hz square-wave a high pitched sound is added. The frequency response, though, is completely flat.

http://www.linkwitzlab.com/frontiers.htm#F

JC

[Wirechief]

Hi JC, Thank you very much for the links and I have wanted some kind of circuit simulation software for a long time but usually very expensive. I did find something yesterday and it is free for the downloading, I don't know how much it will cover but I will try it. I remember something about circuit maker and will be sure to check it out also. I just never realized after starting a Tesoro dealership how interested I would become in the electronics of metal detectors, seems to be a science all its own. I need to order some parts for the HH PI project boards I got from Carl. I have an open account at Mouser and they have always filled the bill. I tell you Eric you guys have inspired me so much that I would consider going to Texas Tech or some place to get an EE. I have gotten out the books and have been rereading quite a bit. I have never met a nicer bunch of guys that truly want to share and help others. Thanks again and CU later JC and God Bless. Wirechief.

[A SARGE LAST HONOR]

Maxim

Meant to provide this link for all of Maxim Continuous Time Filters apps. some good basics in there as well.

http://www.maxim-ic.com/appnotes10.cfm/ac_pk/4

Back to work, no more fun, for awhile.

JC

[A SARGE LAST HONOR]

No problem

Hi Wirechief,

Hope you find something for free that you can use and enjoy.
Otherwise, upgrade, upgrade, upgrade.

If you don't have alot of electronics experience this group delay stuff may get a bit confussing.

But hey just cause you don't understand it, keep reading, after awhile stuff will start to click, i mean beep.

JC

[Wirechief]

Thanks

Ok JC and appreciate the Maxim link and I had found it yesterday, looks like a lot of good stuff. I look forward to going deeper into the circuits and devices. Actually I'm an electronics tech and work with instruments used in the radiation field. At this point in time I'm not competent enough to hang with all of you EE guys but as I said I'm willing to take y'alls advice and instruction to try and absorb the info and learn a lot of new things. I have become a bit stagnant in the last 2 or 3 years and the metal detector theory and electronics along with all of the EE's have given me a new desire to find out what is going on in the black box. The management where I work don't encourage or inspire anyone to try and go higher and learn more, all they want is for you to get the product out with what ever it takes. If we make the monthly goal on sales our bonus is a 5 dollar bill. The goal is usually between 1 to 1.5 million dollars in sales for the plant each month. Heck a 5 dollar bill won't even buy a carton of Blue Bell ice cream! So not any motivation just get it done. I rambled too long so CU later JC and many thanks to you. John, Wirechief.

[Reg]

Hi JC,

I just realized I have a very early copy of Circuitmaker I purchased many years ago. I didn't mind using it at the time , but when EWB brought out the version 5, I found it to be much easier and quicker to use so I switched to it.

I will have to look at the later versions.

Hi Wirechief,

Sorry, I missed your post about EWB. To be honest, I am not sure just what is available from EWB now. I like the version 5 of EWB and find it easy to use but limited.

Later versions of Microsim didn't seem to work nearly as well in my opinion. Now, I haven't tried the latest though.

Reg

[Wirechief]

That's Ok Reg

Hey Reg,
I just want to say hello and thanks for your response and I will look around, I'm sure I can run across some kind of cicuit simulator software eventually. I know that this stuff can get deep real quick but I am very interested. I want to ask you Reg do you do repair on detectors? I am going to build a Hammerhead PI when I get all of the parts. I have a pretty well rounded test bench and enjoy building kits. CU later Reg and appreciate always your knowledge and help. God Bless, John Wirechief.

[A SARGE LAST HONOR]

more spice

Hi Reg,

The first EW for $299 would not do but like 3 cycles on a random waveform, no group delay, and a bunch of other things missing. Had to hook up a scope (rather than have a graph), and gave alot of flat wrong answers.

Later on they had some "Pro/better" programs from EW had graph for output, did group delay, and put most features back in.

Understand that these simulators are all based on the Univ. of Calif. Berkley spice engines.

The 2f6 engine is the old Fortran engine which had converance problems on intergals and other things.
Microsim Pspice spent there own money to fix these and other problems. Pspice and the some other expensive ones do FET modeling much better than basically the toys (EW and CircuitMaker {cheap versions}) and one reason why they cost much much more. There is more to this story as well.

The 3f5 engine is a C based engine and newer (for what that is worth). It has bugs as well but this is another long story.

These simulators basically turned the schematic into net list for the simulator to digest and then provided data out to plot or put on scope screen or whatever. All the companies do. Don't ask how some can get it wrong, but they do!

Hopefully your EW5 doesn't have features crippled.
{and that is what they do cripple em cause they don't want to deal with them, or explain em, they are in the engine}

Can you do group delay? Monte Carlo analysis?
Noise? Any noise?

If you can do group delay, do it on Eric's circuit.

Thanks Reg.

Free spice link

http://www.repairfaq.org/ELE/F_Free_Spice.html

JC

[A SARGE LAST HONOR]

Free spice

Hi Wirechief,

Try some of these for free, don't buy anything for a while, until you are sure what you want.

Have Fun,

JC

[Wirechief]

Thank you

Ok JC I will be sure to check them out and look around with caution to be sure I can get what I need. CU later much appreciated! John, Wirechief.

[A SARGE LAST HONOR]

EW version 5

Hi All,

found a link for info on EW5.

Btw, WireChief, your will want version 8.0 on the microsim Pspice, it's a demo, and a pain, and slow, but provides more "true" answers if this becomes important.

EW5

EWB is very fast, faster than the conventional PSPICE-based simulators in mixed analog-digital simulation mode and it is very easy to learn and use. For those reasons only it can make even the Systems and Software stream students attracted to solving hardware problems - a phenomenon hard to believe though witnessed by myself on a number of occasions. Its limitations may not be noticed by users - that the laboratory is virtual, i.e. it is idealised. The noise is not present and the output plots (whether accurate or not) are produced with a wide choice of simulation parameters. Therefore engineering users need their own good judgement and some caution.

{no noise, damn}

Version 5 offers access to most simulation and convergence options, to make regular engineers happy. For that reason, it is very different from Version 4.1 which offers access to two only: the number of iterations per timestep and the limiting accuracy.

Using either a 486DX-66, PentiumC90 or even Pentium Pro200 with small or large numbers of monitored nodes had little effect on the performance but the size of the circuit had. Generally as a circuit was approaching the size of the full screen, the simulator was struggling and would eventually give up complaining about too demanding iteration conditions (although I was already at the most relaxed end of the scale). Version 5 (32 bit) performed a bit better. Like in a real laboratory, problems may be avoided by developing circuits gradually, starting at a minimum complexity and using idealised models. This is because convergence difficulties are sparked by the accumulation of demanding or critical nodes in a circuit, especially when their requirements are contradictory (like the size of iterations for integrating components vs sharply nonlinear ones).


http://science.uniserve.edu.au/newsl...0/lesniew.html

Btw, Spice3 is the 3f5 engine, is faster, and CM and EW both use it.

JC