[EE] Looking for NE531 alternative

[Alex Harford]

I'm looking for a replacement op amp for the NE531 to complete some
boards on an old design. I haven't had much luck as it seems to have
been obsoleted around 1999. The client has a lot of PCBs leftover
from an old run, so a drop-in would be ideal. Perfect would be a
surplus tube somewhere, but I haven't had much luck.

The design is possibly older than myself, so much of the original
documentation is non-existent. The part is used in two places, a
unity gain follower and a half wave rectifier. I assume it was chosen
due to high (35V/usec) slew rate.

The pinout looks the same as the TL070 which seems more common (but
also obsoleted). Some parts have looked promising, but the offset
null / compensation pins were swapped.

- Power supply is +15V,-15V
- Incoming signal is ~30kHz

Op amps are not my area of expertise, external compensation capacitors
were new to me, so I've been doing a lot of reading up on the details.
I'm still working out how much of the circuit works. Any suggestions
would be appreciated.

Thanks,
Alex
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[Marcel Duchamp]

This company shows possible stock:

http://www.questcomp.com/QuestDetailsAll.aspx?pn=NE531H&pnid=87744&stock=YesOnly

I've never used them and know nothing about them. I have used
partminer.com with very good success last year so they are probably
worth a try. Make sure you know the right suffix for package type, etc.

[YES NOPE9]

>
> On Jun 21, 2010, at 2:17 PM, Alex Harford wrote:
>
> I'm looking for a replacement op amp for the NE531 to complete some
> boards on an old design.

Pin-for-pin replacement for µA709, µA748, or LM101

The LM301A appears to be a replacement.
They are 67 cents at DigiKey
Gus

[Bob Blick]

On Mon, 21 Jun 2010 13:17:47 -0700, "Alex Harford" said:
> I'm looking for a replacement op amp for the NE531 to complete some
> boards on an old design. I haven't had much luck as it seems to have
> been obsoleted around 1999. The client has a lot of PCBs leftover
> from an old run, so a drop-in would be ideal. Perfect would be a
> surplus tube somewhere, but I haven't had much luck.

Hi Alex,

The NE531 in 8 pin DIP is available locally, I bought some recently as
spares for an old power amplifier I have. I can probably go to the store
on my way home from work today, I'll see how many they have and email
you directly.

Cheerful regards,

Bob

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[Alex Harford]

On Mon, Jun 21, 2010 at 1:36 PM, Marcel Duchamp
<marcel....@sbcglobal.net> wrote:
> This company shows possible stock:
>
> http://www.questcomp.com/QuestDetailsAll.aspx?pn=NE531H&pnid=87744&stock=YesOnly
>
> I've never used them and know nothing about them.  I have used
> partminer.com with very good success last year so they are probably
> worth a try.  Make sure you know the right suffix for package type, etc.

Argh, should have mentioned that I need them in a DIP package, NE531N.
CERDIP would be fine, so SE531FE/NE531FE would work too, although I'm
sure they are more $$$.

For alternative parts, I should have also mentioned that the signal is
going to be 7V max, no DC offset.

[peter green]

>
> Op amps are not my area of expertise, external compensation capacitors
> were new to me, so I've been doing a lot of reading up on the details.
> I'm still working out how much of the circuit works. Any suggestions
> would be appreciated.

The placement of the main pins seems the same as a 741.

I wonder if you could find a more modern op-amp that meets the
performance requirements without requring any external offset null or
compensation circuitry and can therefore be dropped in (possibly with
some of it's legs cut off).

[Spehro Pefhany]

At 05:05 PM 21/06/2010, you wrote:
>On Mon, Jun 21, 2010 at 1:36 PM, Marcel Duchamp
><marcel....@sbcglobal.net> wrote:
> > This company shows possible stock:
> >
> >
> http://www.questcomp.com/QuestDetailsAll.aspx?pn=NE531H&pnid=87744&stock=YesOnly
> >
> > I've never used them and know nothing about them. I have used
> > partminer.com with very good success last year so they are probably
> > worth a try. Make sure you know the right suffix for package type, etc.
>
>Argh, should have mentioned that I need them in a DIP package, NE531N.
> CERDIP would be fine, so SE531FE/NE531FE would work too, although I'm
>sure they are more $$$.

Can't you bend the leads from a TO-5 into a DIP pattern?

This company says they have some too:

http://www.4starelectronics.com/part_detail/NE531N.html?cmpid=2007

Qty In-Stock:
<http://www.4starelectronics.com/part_search/straightrfq.asp?PART_NUMBER=NE531N>76
pcs
Qty Available:
<http://www.4starelectronics.com/part_search/straightrfq.asp?PART_NUMBER=NE531N>12,058
pcs

>For alternative parts, I should have also mentioned that the signal is
>going to be 7V max, no DC offset.
>
>--
>http://www.piclist.com PIC/SX FAQ & list archive
>View/change your membership options at
>http://mailman.mit.edu/mailman/listinfo/piclist

Spehro Pefhany --"it's the network..." "The Journey is the reward"
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