Magnum I II (VLF) semiconductors

[baht7]

Magnum semiconductors list CA3130 and the CA3140, both cross to NTE-7144.
I used another site to cross check this.....

CA3140E
LF351N
National Semiconductor: 4.5MHz, BiMOS Operational Amplifier with MOSFET Input/Bipolar Output

CA3130E
LF357N
National Semiconductor:15MHz, BiMOS Operational Amplifier with MOSFET Input/CMOS Output

NTE-7144: BIMOS Operational Amplifier w/MOSFET Input, Bipolar Output


Can I go with the NTE-7144 for both ICs?

[ivconic]

Good question!
I am struggling also with CA3130 and CA3140 in many designs i plan to do!

[silverdog]

Good question!
I am struggling also with CA3130 and CA3140 in many designs i plan to do!

Are you struggling to obtain these IC's ?

[ivconic]

Yes. Those are obsolete and seems discontinued (not sure, but think so).
Cscope and White's older designs are using such opamps.
Maybe some others too.
So, usually i try to replicate some parts and stages from such older designs, with intentions to experiment with them and see how such stages will work in different setup.
That's how i learn about md stuff. Because best knowledge, amateur (like i am) can get, is already presented in older designs from major manufacturers.
Man need only good will and pile of original schematics ...nothing else. And original components...of course!
But frequently i miss some original components as CA3130 or CA3140 and am not sure if that particular stage is working good with replacement or not?
I take some (by wild guess mostly) replacement and put instead.
Later, if not working as i expect, i rise doubts in almost everything!
That's why is better to initially use original component and not substitution, because many things from real life are not fully compatible with theory offered in datasheets...

[Qiaozhi]

Yes. Those are obsolete and seems discontinued (not sure, but think so).

http://uk.farnell.com/jsp/search/bro...questid=143985
http://uk.farnell.com/jsp/search/bro...questid=144296
http://uk.rs-online.com/web/c/?sra=o...ca3140&x=0&y=0
http://uk.rs-online.com/web/c/?searc...ca3130&sra=oss

[Sean_Goddard]

Be aware that the reason our dear compatriot Ivconic is having problem obtaining these IC's may well be due to ITAR classification!

I KNOW Bulgaria are our allies now, but ITAR doesn't always reflect this. There are plenty of equivalents out there. ANY CMOS or BiFET input op amp would do.

Any was a personal friend of mine before he died tragically a few years back, he told me most any high input impedence IC could be used, but to make sure it was LOW NOISE!

He was planning a NEW VLF machine with revolutionary discriminate methods. I saw the shematic he was working on but did not get a good enough look to remember how he had done it. I might ask his wife if I she still has them and I can buy them.

God Bless Andy Flind!

[baht7]

so....Its a YES on the NTE-7144 noting (low noise)

[porkluvr]

so....Its a YES on the NTE-7144 noting (low noise)

I hate to rain on your parade, but that's wishful thinking.

I haven't written a book in a while and I've got to add my two cents worth. Some fact, but mostly just my opinion... .

Andy wrote that the CA3140 was specified in the Magnum IB because of its combination of high impedance and wide input range. Here's what I think: both of those attributes aren't really needed at the same time, except in the TUNE stage. Of the three slots for the CA3140, the other two slots could probably just as well use either TL071, or LF351 (etc.).

NTE7144 is a good general purpose replacement for CA3140 but I think NTE stretches the truth (er, um told a lie) by suggesting that NTE7144 is s suitable replacement for CA3130. Sure, it would work to some degree, no doubt...

Should we say, "they're both CMOS input devices with eight leads, and they both have a strobe pin, so that makes them similar"? No, because that is about where the similarity ends.

The CA3130 is an uncompensated opamp with slew rate of 30V/us. Meanwhile, the NTE7144 (also CA3140) is compensated for unity gain and has slew rate of only 7V/us. The Magnum IB uses the CA3130 open loop, as a comparator... and that is exactly the type of application where slew rate matters.

For the CA3130 slot you would probably be better off using LF357 if you can get one. They're fast but they're not cheap. BUT if you can't get CA3130 or LF357, you should not waste a NTE7144 there, unless that's all you have. Why not? Because there are lots of cheaper devices that can do the job just as well. For instance, although TL071 will not match the CA3130 when used as a comparator, it should fairly match the NTE7144, and it usually costs a lot less. Either should work about as good (or bad) as the other, but one costs less.

What I am saying is that NTE7144 will undoubtedly work in place of the CA3130, but, you should not expect it to perform as well. It is not nearly as fast, and it is being used where speed does matter. There are lots of cheaper amplifiers that will do that job just as well and so, you might as well use something less expensive.

You would be smart to use the NTE7144 in the THIRD slot for CA3140 (in the tune circuit) because you need an amplifier with low bias current, having an input voltage range that extends to the negative rail. There, TL071 would not do a good job. CMOS input amps are better for that.

Just about any (low noise) BiFET opamp (TL071, etc.) would work in the case of IC4 and IC9, but the Tune circuit needs to be able to amplify signals buried almost in the negative rail and most BiFETS will not do that. That's where NTE7144/CA3140 should be used. And for IC3 (CA3130), you want an amplifier that is faster than most. If the CA3140 was not a good choice for the IC3 slot, then NTE7144 also would not be good, because they are very similar. And, if CA3140 was a good choice, then Mr. Flind probably would have simply specified 4 ea. CA3140 , but he did not.

Sorry, that was kind of long but I'm not going to try and edit it down.

[ivconic]

Prokluvr you should move to my neighborhood asap!
Because i will need such nice elaborations more frequent in the nearest future!
And other reason is because Sokobanja is better place to live than Charlotte!
Splendid overview!
It is helpful!
Many thanks!
Regards!

[porkluvr]

Prokluvr you should move to my neighborhood asap!
...because Sokobanja is better place to live than Charlotte!

You're probably right about that but I am horrible with learning foreign languages.

I've got a copy of "IC Op-Amp Cookbook" by Walter G. Jung that details a lot of opamp development history. CA3140 and CA3130 have their own writeups.

I won't tell you how long I've had it because that would give away how old I am.

[ivconic]

Don't worry about language, people here (especially new generations) are speaking English by the rule.
"IC Op-Amp Cookbook" by Walter G. Jung ?
Is it available on the net?
Now i am itched to find it out!
Will look for it....
Thanks!
Cheers!

[porkluvr]

I have tried to find a 'freebe' ebook for download but could not.

You can get the book I mentioned from Amazon. Here is but one of many possible Google results:
http://www.amazon.com/Op-Amp-Cookboo.../dp/0138896011
HOWEVER
Walt recommends not purchasing a recent printing of his book "IC Op-Amp-Cookbook" because of poor print quality.

Jung used to be an IC designer for Analog Devices.
Check this out:

http://waltjung.org/index.html

There are links to search for his books and also some very interesting free application notes.
I only just today found Jung's website. Lots of good stuff.

[ivconic]

[porkluvr]

I don't want to beat a dead horse but I want to correct some inaccuracies in my post #8.

I stated that IC9 could probably be replaced with a BiFET opamp. BiFET means having JFET inputs. [Actually, if I am not mistaken, BiFET is a proprietary term coined by Burr-Brown (now part of Texas Instruments)... but it denotes JFET inputs iirc.]

BiFET has low input bias currents, but CMOS input opamps such as CA3140 generally have substantially lower input bias currents necessary for correct auto-tune circuit operation. IC9 would better be filled with a CMOS input opamp, which points to the CA3140 or NTE7144. The extremely high input impedance of CMOS will help minimize the operator having to hit the RETUNE button. You should NOT use a JFET input opamp for U9 if you want best performance.

Not only that, but when I implied that IC10 was best filled by the CA3140 or NTE7144 (but not to use a BiFET), I was correct - but for the wrong reason. I touted the CA3140 having a wide input voltage range, and while that is good - what IC10 really needs is that it should have a wide output voltage range; swinging almost to the negative supply. That is necessary to quench the audio output in the presence of no target signal. Most JFET input opamps will not swing their outputs to within half a volt of the negative rail.

What remains unchanged is that you could probably use TL071 for IC4 and not suffer any loss of performance. Just my opinion.

I appologize for any confusion that I may have caused. It was late and I chose to deviate from a narrow focus in my mini-lecture. It was a case of "open mouth, insert foot."

The main thrust of my previous post was that the NTE7144 does not really make a good substitute for the CA3130 in the IC3 slot, and I stand by that statement.

Remember, these statements are mostly my opinions. Substituting opamps is not usually a black-or-white issue where something either works or it doesn't, it is usually going to be an issue of degrees of better or worse performance.

[porkluvr]

I'm sorry, "DiFET" was coined by Burr-Brown (now part of TI). "BiFET" is used by Analog Devices and I am not sure if a proprietary or not. I should know but I don't. It has come to be used as a generic term for JFET inputs.


It makes no difference anyway.