Can someone educate me about the MC144B (or MC1448) dual op-amp?

[Mark Hammer]

I was looking through the schematic and documentation for the Audio & Design recording S24 ("Scamp") Time Shape Module. A friend with a busy and reputable studio needed a couple of SAD1024 chips to revive one of these, and I got interested in the unit. As flangers designs go, it's a pretty intense unit. It tends to use CA3240, 3260, and TL082 dual-amps throughout (so one gets the sense that op-amp types were selected for a context-specific reason), but also uses some dual op-amps I'd not come into contact with before. Since it is a scan and the print is small, I am not dead certain whether they are MC144B or MC1448. Either way, it is a standard pinout dual op-amp, and I can't seem to find info on either of them.

Anybody have any familiarity with the chip in question?

[g1]

Could it be 1458 ? I think 1448 is a display driver. If it's 1458 it is similar to 4558, sometimes interchangeable but not always.

[Mark Hammer]

No, it's definitely 144-something, and not 1458. And looking at the rest of the 4-page schematic, I'm more confident that it's 144B than 1448. Can't seem to find any datasheets for it though. I imagine, given the age of the S24, it might be something I find in an old Motorola linear devices book, in one of those appnotes where you find there are devices with similar numbers. For example, if I look up a datasheet for an LM308 single op-amp, I find out, much to my surprise, that there also exist 108 and 208 chips.

[tedmich]

is 144B read off schematic or actual CHIP? many errors in schematic labeling...none on chips though!

its a DIP8? or SMD? Anything else on chip to narrow Mfg?

[Mark Hammer]

Just the service manual. You can see for yourself here: http://rapidshare.com/files/85464364/Scamp_S24.rar

It's from the AnalogRules.com site, a real treasure trove of pro audio documents and schems.

[J M Fahey]

Hi Mark:
1) Rapidshare no longer serves these files so please post your copy here (not the link)
2) Motorola used to add "14" or "34" at the beginning of otherwise common numbers.
So LM741 became MC14741 and so on.
Apply this "rule" to what you have. You already know what it does anyway

[Mark Hammer]

Ah, was unaware of the dead-endedness of the link. How do I post a PDF? Worst case, I suppose I can do a screengrab of the schem and post that. THAT I know how to do.

You're right that I know what it does, with respect to it being an op-amp, and what it is accomplishing in the design. However, since it is used ONLY in the limiter section, and other types of op-amps are used elsewhere, it made me curious about what it does so much better that it merited use in this design. The designers weren't shy about resorting to a humble 741 in other places where nothing demanding was required of the op-amp. So what the heck IS the MC144B that I've never run into it other than this one spot in this one device?

[tedmich]

google documents works for pdfs if you're not shy

[J M Fahey]

Well, MC144B it is not, for sure.
You need at least 5 digits there.
As of your PDF: "Go Advanced" and attach the file.
Humble 1458 were often used instead of "better" ones because they seem to provide more output current if needed, as in Reverb drivers, headphone amps and Music Man cathode driven amps, so if you see some use like that, it might be it.
So yes, I agree, not all are exactly the same.
In a nutshell: MC14-something is a very popular prefix, but only indicates it's a Motorola child.
You still need the rest of the data.

[Jazz P Bass]

I tried LM144, National Semi.
Maybe this will help.
There is this little blurb on the LM143 datsheet: '* An externally compensated version of the LM143, the LM144, offers even
higher slew rate in most applications. The LM144 is pin-for-pin compatible
with the LM101A.'

[Mark Hammer]

Well thanks for the tip. You learn something new everyday. Here's the file. You can see for yourself.

[Enzo]

Wow.

I got out my Moto linear book from the 1970s, as well as a couple selector guides, and a cross reference to other manufacturers numbers. I find no MC1448 or MC144B in Motorola. And as far as I can tell, they did not cover a National LM144. And my ancient ECG book doesn;t cross either one.


ANy chance it is a typo? WHoever drew that thing had 1448 instead of 1458 in his head?

[J M Fahey]

Agree with Enzo.
Certainly the 1458 glove fits that hand very well.
The 144 is a single op amp ; the 143 too, so .... not compatible.
Besides, although distorted, the 8 is clearly narrower than the B , just look at the BC182B where both characters are close by.
And elsewhere in the schematic.
And there are not *that* many Op Amp types specified.
Almost everywhere there are the 3240 or 082 ... both FET input, and as a bipolar our mysterious 1448 .... which might be a 1458 as Enzo suspects.
And 1458 does exist, as well as its "better" version 1558.
http://www.oup.com/us/pdf/microcircu.../mc1458-st.pdf

[doctor]

Agree with Enzo.
Certainly the 1458 glove fits that hand very well.
The 144 is a single op amp ; the 143 too, so .... not compatible.
Besides, although distorted, the 8 is clearly narrower than the B , just look at the BC182B where both characters are close by.
And elsewhere in the schematic.
And there are not *that* many Op Amp types specified.
Almost everywhere there are the 3240 or 082 ... both FET input, and as a bipolar our mysterious 1448 .... which might be a 1458 as Enzo suspects.
And 1458 does exist, as well as its "better" version 1558.
http://www.oup.com/us/pdf/microcircu.../mc1458-st.pdf

In accordance with schematic non-inverting inputs of this op amp
are connected to the 100K resistors.
Despite the fact that even for bipolar op amps non-inverting inputs have
relatively high impedance, FET-input dual operational op amp must be
used for replacement. Only such op amp can realize low noise performance
in this circuitry. This is important particularly in the input circuitries.

The TL072 or more modern op amp can be used.

[Mark Hammer]

Here is where I wish I had one of those old IC cross-reference books; the ones that were several thousand pages thick, on onion skin paper with 6pt font. They would include house numbers as well as standard manufacturer prefixes.

We're assuming it's Motorola and a standard part number....but IS it? It's hard for me to believe that a design with so much attention paid to detail would simply chuck in a 1458 in a peak limiter. I mean, cripes, the design differentiates between CA3240 and 3260, which is pretty dang picky.