Legit LM307?

[Crix1990]

Hi together,

I was looking for some LM307 for a Music Man style pedal and found a ebay dealer in Germany (where I'm from) that sold 4 NOS in TO-78.
I never bought there before, but over all the dealer looks very legit and specialized to NOS chips.

For curiosity, are there fake LM307 around, and is there a way to measure it like for LM301 and LM308?





Thank you and regards,
Felix

[PRR]

The '307 is an other-brand '741.

[Rob Strand]

The '307 is an other-brand '741.

It's an compensated LM301A,  slightly different input structure to the LM741.
https://www.analog.com/media/en/technical-documentation/data-sheets/lm101a.pdf

(Going the other way an LM748 is an uncompensated LM741.   Not quite the same offset control though.)

For curiosity, are there fake LM307 around, and is there a way to measure it like for LM301 and LM308?

Well you could work through the datasheet.  It would be fairly tedious.   The main claim to fame of the LM301A/LM307 was it's ability to work with a common mode voltage upto the +ve rail.

IIRC duck_arse or Kevin Mitchell had a thread running on the LM301A not too long ago.   What's weird is the LM301A's aren't all the same.  Different resistances between some of the pins on different units.  Also different schematics in different datasheets.

Found the thread,
https://www.diystompboxes.com/smfforum/index.php?topic=130160

The LM308A's are different again.  Low input bias currents and slower.  Lower short circuit current?

[Crix1990]

Yes, I saw the threat about the LM301 and a nice Youtube video that does the same for the LM308.

So as I see from the datasheet, I should not have any connection on Pin 1, 5 & 8.
But from the schematics, I do not see any resistance, I could measure, incl. the "famous" 6 to 8 measurement from the LM301.

Do I see this right?

[duck_arse]

welcome to the forum, as they say.

do you see any brand markings, or just the part numbers? we love looking at old parts. if you can measure any internal connection on those 3 pins, the part doesn't match that datasheet. does that hold for all manufacturers?

[Rob Strand]

So as I see from the datasheet, I should not have any connection on Pin 1, 5 & 8.
But from the schematics, I do not see any resistance, I could measure, incl. the "famous" 6 to 8 measurement from the LM301.

Do I see this right?

I checked the details of a few datasheets.  You are seeing right.   Pins 1, 5, 8 are explicitly quoted as NC (no connection) on the LM307.   I wasn't aware the offset adjust was removed from those.

So yes, that's going to make it difficult to check.   If you measure no connection from each of pins 1,5, 8 to the rest and see nothing that is actually information favoring a legit LM307.   Checking the common mode works to the +V rail is another.   Bandwidth and slew-rate perhaps another.   The presence of an input bias current would rule out any JFET input subs.

[Crix1990]

First of all sorry for the delayed answer, was a busy time...
So I cheked my 307s, indeed pin 1, 5 & 8 are not connected to anything.
I found the info in the datasheet from National, that pin 4 should be connected to the housing, and it is.

I think with these very specific configuration, I can say that mine are legit (they are from National), or does anyone know ICs with the same pin config?

I also did a photo session with one of it for you.











Regards,
Felix

[Rob Strand]

I think with these very specific configuration, I can say that mine are legit (they are from National), or does anyone know ICs with the same pin config?

I also did a photo session with one of it for you.

Agreed, it's quite specific.  There's little to make the think these are anything but legit parts.

I think the wiggly logo, as shown in your pics, was 1977 and after.   You could check the date code - I can't see the date code on your pics.

[Crix1990]

Yeah, since the dealer was a german ebay shop that only had NOS parts, and just four of these, I had the feeling that these will be legit.
I would bought these on a untrusted mass shop.
I payed a little more than 20€ for all, so I think it's a rare good deal...

So the production code says on all S:H8806.

Regards,
Felix

[Rob Strand]

So the production code says on all S:H8806

1988 is consistent with the wiggly logo.   National didn't go to the "script N" logo until about 1995.

Your parts tick a lot of boxes