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Photodiode case

J

Joerg

Jan 1, 1970
0
Phil said:
Those were nice parts. I still have some left too...iirc they're in the
1989 data book. I'll look them up and see if I can post the
datasheet--basically they were the LF3xx series with the current limit
resistor pinned out separately, so you could use higher current at lower
supply voltages.

National did some *weird* stuff in 1988--they came out with about 20 new
*hybrid* designs, like the LH4009 buffer. Of course, those lasted about
2 years and went the way of the dodo. I still have some.

They also did some not-so-nice stuff. Brought LH0063 and 0033 buffers to
market, excellent parts, used by ATE folks all around the globe, then
sent out the funeral notice. Now there is the occasional fist fight
among obsolete-parts dealers if a stash shows up somewhere.
 
J

Joerg

Jan 1, 1970
0
Ecnerwal said:
Meanwhile I'm sitting on 20 or so LF455/6/7 which obviously did not
survive the intervening 20 years, so I hope I can find the right paper
book (I have some stashed here, and some elsewhere), as National does
not have the datasheets for those on-line, and I'm not over-fond of the
"pay money for datasheet" people. My op-amp book stops at LF453...

Of course there's also the "do I want to use them at all, if they have
been weeded out of the stream" consideration, but I hate to waste things
(other than storage space, evidently).

Lawrence, I've got two pages for it in the 1988 databook here. But it's
very little data because they called it "advanced information". Those
parts must have kicked the bucket almost before hitting the market
because there is no mention at all in the 1995 databook. IOW maybe there
never was a publicly released datasheet. Maybe Bob Pease has one ;-)

Do you want those two pages? If so, do I just leave the "y" out of your
email address?
 
E

Ecnerwal

Jan 1, 1970
0
Joerg said:
Do you want those two pages? If so, do I just leave the "y" out of your
email address?

Thanks, Joerg - Take out all the lowercase to email, and yes, I would
appreciate those. I _may_ have more data on them in a box somewhere,
but certainly my OpAmp book which is to hand is the 1995 version. The
parts themselves appear to be from the 40th and 42nd week of 1989, in
cute shiny metal can (CIH) packages.
They also did some not-so-nice stuff. Brought LH0063 and 0033 buffers to
market, excellent parts, used by ATE folks all around the globe, then
sent out the funeral notice. Now there is the occasional fist fight
among obsolete-parts dealers if a stash shows up somewhere.

Got only one LH0063 in the hoard, unfortunately. Should I put it on *B*y
and retire from the proceeds? Somehow I doubt it would come to much...
Looks like one vendor is flogging 8 of them at $60 each.

I have to agree that it was bizarre to bring out such nice, useful stuff
and then axe them so quickly.
 
J

Joerg

Jan 1, 1970
0
Ecnerwal said:
Thanks, Joerg - Take out all the lowercase to email, and yes, I would
appreciate those. I _may_ have more data on them in a box somewhere,
but certainly my OpAmp book which is to hand is the 1995 version. The
parts themselves appear to be from the 40th and 42nd week of 1989, in
cute shiny metal can (CIH) packages.

Immediately after sending I got a totally blank bounce message with no
sender info in there. Some ISPs think that spam protection is that easy,
dumping whatever they like. Do you have a better email address?

Got only one LH0063 in the hoard, unfortunately. Should I put it on *B*y
and retire from the proceeds? Somehow I doubt it would come to much...
Looks like one vendor is flogging 8 of them at $60 each.

Yep, that's the going rate these days I believe.

I have to agree that it was bizarre to bring out such nice, useful stuff
and then axe them so quickly.

The larger corporations get the larger the number of really bad
blunders. They don't even know how miffed some of their good customers
became. National is otherwise ok but there are some companies I have on
a strict blacklist where there will be guaranteed no design-in of any of
their parts in this office.
 
J

Joerg

Jan 1, 1970
0
Phil said:
Win,

I know about bootstrapping the PD...I've used that approach often, and
combined it with the common base idea as well. It's bootstrapping the
cable shield I meant. The original 'ghost shield' approach from WWII
sonar looks like magic but costs beaucoup SNR. The SNR of a
bootstrapped RC front end is the same as the SNR of the same amp
connected as a follower on the same RC rolloff--only the transfer
function changes.

Not for you as the expert, of course, but for fellow readers who might
not yet be familiar with PD bootstrapping:

http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1009,C1026,P25554,D16998

In cases where this link doesn't work, it is Linear's Design Note 399.
 
P

Phil Hobbs

Jan 1, 1970
0
Joerg said:
They also did some not-so-nice stuff. Brought LH0063 and 0033 buffers to
market, excellent parts, used by ATE folks all around the globe, then
sent out the funeral notice. Now there is the occasional fist fight
among obsolete-parts dealers if a stash shows up somewhere.
You can't blame National too much for those two--they stayed around for
20 years or so, unlike the 1988-89 vintage.

I still have about 25 LH0063Cs. I used those and LH4009s back in the
day to test sensor back ends--you record the front end outputs for
signals of interest, mainly just-missedits and squeakers-under-the-wire,
and store them. To test the back ends, you grab hold of some poor op
amp's output with an LH0063 and force it to replay the canned data.
Works great. Too bad you can't get them anymore.

Cheers,

Phil Hobbs
 
J

Joerg

Jan 1, 1970
0
Phil said:
You can't blame National too much for those two--they stayed around for
20 years or so, unlike the 1988-89 vintage.

I still have about 25 LH0063Cs. I used those and LH4009s back in the
day to test sensor back ends--you record the front end outputs for
signals of interest, mainly just-missedits and squeakers-under-the-wire,
and store them. To test the back ends, you grab hold of some poor op
amp's output with an LH0063 and force it to replay the canned data.
Works great. Too bad you can't get them anymore.

You can get good money for those. I bet National could also turn a nice
little profit from them if they brought them back. I mean, they don't
have to produce them domestically.

The LH0033 was also good but much harder to cool.

BTW I've got a two-pager "advanced notice" about the LF455/6/7 series
from the 1988 databook. Let me know the address if you want it emailed.
Interestingly, in the 95 book they are gone. Must have been one of the
most short-lived opamps ever.
 
P

Phil Hobbs

Jan 1, 1970
0
Joerg said:
Not for you as the expert, of course, but for fellow readers who might
not yet be familiar with PD bootstrapping:

http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1154,C1009,C1026,P25554,D16998


In cases where this link doesn't work, it is Linear's Design Note 399.

I've actually never used a BF862, so I ordered some....I have 4 weeks
vacation left, so I have to spend it somehow. Between that and
investigating copper clad shielding as a function of frequency, I think
I have a fun holiday season ahead.


Cheers,

Phil Hobs
 
J

Joerg

Jan 1, 1970
0
Phil said:
I've actually never used a BF862, so I ordered some....I have 4 weeks
vacation left, so I have to spend it somehow. Between that and
investigating copper clad shielding as a function of frequency, I think
I have a fun holiday season ahead.

I am surprised there is no detailed noise data available for it. For
example how the noise develops for audio and below. From a marketeers
perspective I don't understand that lack.
 
J

Jure Newsgroups

Jan 1, 1970
0
Winfield Hill said:
They say Vos = 20mV max, what have you
found in practice?

in my small sample of about ten devices : 6 mV max , 3mV more common.

Jure Z.
 
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