got some op-amps today...

[O'malley's Alley]

today my dad gave me some of his op-amps.  I'm fairly new to op-amps, but here are the ones that I have (im just gonna type exactly whats on the op amp):

-opa2604ap
9429 5057

-RM5534DE
RAY
08836

-NE5532AFE
QFP7039
8821VG

-NE5532AFE
8649D

-71 X B
NE5532P (looks like it has the texas instrument logo on i)

-NE5532AN
8523A

-OPA2107AP
9515 4714

Does anyone have any experience with any of these, and which ones are good for which projects?  Sorry, I'm kinda new to op-amps, I figured you guys could help me....

[Peter Snowberg]

Cool!

The NE5532 is a very common, low noise, low impedance output opamp. It's my favorite BJT opamp by a big margin. The 5534 is a single version of the 5532 which is a dual.

The OPA2107AP and OPA26094 are super high quality FET opamps.

Datasheets:
http://focus.ti.com/docs/prod/folders/print/ne5532a.html
http://focus.ti.com/docs/prod/folders/print/opa2107.html
http://focus.ti.com/docs/prod/folders/print/opa2604.html

You scorred BIG time.

Take care,
-Peter

[O'malley's Alley]

yes, I did score big time.  Plus I got many of them.  I have about 17 of the opa2604ap's, and I have at least 20 RM5534DE's.

[O'malley's Alley]

BTW: Do you have any or know of any schematics that use the OPA2107AP's and the NE5532's.  im not much of an engineer, so schems would be nice...

[Peter Snowberg]

Think of the 5532 as a super high quality 4558s.

Think of the OPA2x0x chips as super high quality TL072s.

If a circiut uses an opamp, you're all set. Those chips are direct substitutions (pin compatible).

The 5534 is almost a direct sub for the 741, but you may have to "adjust" what you do with pins 1, 5, and 8. The other pins are the exact same.
http://focus.ti.com/docs/prod/folders/print/ne5534a.html
http://cache.national.com/ds/LM/LM741.pdf

Take care,
-Peter

[Mark Hammer]

5534 (single version) and 5532 (the dual version) have the helpful and generally unique property of being able to deliver lots of current to small loads.  Normally, op-amps don't like to see low-resistance paths to ground at their output but the 553x chips are pretty cool (literally and figuratively) with that.  As a result, they are often used for headphone amps, since headphone drivers are generally in the 32ohm and under range.  Check out the PAiA website for some of their schems using it in this way (e.g., http://www.paia.com/hdasch.gif ).  Some writers suggest that they can also deliver sufficient current into a speaker to work as a low-power practice amp.

Dave Barber of Barber Electronics recently posted a thread concerning the paralleling of opamps for greater current delivery.  Like you, I also came into receipt of a fistful of 5534's so I figured I try it out.  I stacked one 5534 on top of another so that the pins lined up, soldered them together, and plugged it into my Distortion+ clone.  Sounded great, and to my ears had a little more note definition than a standard 741.

Normally, when people make little practice amps, they tend to turn to the LM386 which is a half-watt power amp.  The 5534 is probably capable of duplicating what the 386 does and if you parallel a pair of them probably moreso.  So there can be your first experiment.  Make yourself a little practice amp.

The PAiA design assumes you're feeding the headphone amp a line level signal, so you'll need to add a little more boost if you plan to plug your guitar straight into it.  I'm pretty sure your dad can help you out there.

You've scored big in two ways: a) you got some good chips cheap, and b) you have a dad with good taste complemented by generosity.

[Nasse]

The 5534 is almost a direct sub for the 741, but you may have to "adjust" what you do with pins 1, 5, and 8. The other pins are the exact same.

I remeber 5534 is not unity gain stable (you can not use it as voltage follower or unity gain buffer without doing something with pins 1, 5,

:roll: But they are nice opamps

[O'malley's Alley]

You've scored big in two ways: a) you got some good chips cheap, and b) you have a dad with good taste complemented by generosity.

my dad rocks.  He doesn't use IC's anymore cause he only builds tube amps (audio) these days.  He is also very informative.  I like the idea of the two chips in parallel, maybe I'll try that out...

[Peter Snowberg]

Check out this thead for more on paralleling opamps:

http://www.diystompboxes.com/sboxforum/viewtopic.php?t=16784

Cool stuff!

Take care,
-Peter

[O'malley's Alley]

Ok, another question.  on some schematics, they dont give the pin numbers of the IC's.  How do I tell what the pin numbers are?

[Peter Snowberg]

Just compare the symbols on the schematics with the data sheets and there you go. You may want to save a local copy of those datasheets on your machine too.

The pinouts for almost all dual opamps are the same. After you deal with them for a while the pin numbers will just sink into your mind and you won't be able to forget them.

Take care,
-Peter