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From: Jim Flanagan on 7 Nov 2009 23:27

Phil Allison wrote:
> "Jim Flanagan"
>
>> I need a replacement for this device in an 8pin dip package. Does
>> anyone have an extra they want to sell or barter?
>>
>> These a unity gain, Jfet, buffers.
>>
>
> ** Better take a look at a data sheet.
>
> The LM310 is not jfet.
>
>
>
> ..... Phil
>
>

Yes... you are quite right. Not sure where I got 'JFET' input from?
Thanks
>
>


From: Phil Allison on 8 Nov 2009 00:58

"Jim Flanagan"
> Phil Allison wrote:
>
>>
>>> I need a replacement for this device in an 8pin dip package. Does
>>> anyone have an extra they want to sell or barter?
>>>
>>> These a unity gain, Jfet, buffers.
>>>
>> ** Better take a look at a data sheet.
>>
>> The LM310 is not jfet.
>>
>
> Yes... you are quite right. Not sure where I got 'JFET' input from?


** 1nA input bias current gives one that sort of impression.

Seems to be using the same "super gain" NPN transistors for the inputs as
the LM308 does.

Amazing stuff for ICs released in the late 1960s.



...... Phil




From: Bill Sloman on 8 Nov 2009 13:51
On Nov 8, 6:58 am, "Phil Allison" <phi...(a)tpg.com.au> wrote:
> "Jim Flanagan"
>
> > Phil Allison wrote:
>
> >>> I need a replacement for this device in an 8pin dip package.  Does
> >>> anyone have an extra they want to sell or barter?
>
> >>>  These a unity gain, Jfet, buffers.
>
> >> **  Better take a look at a data sheet.
>
> >>      The LM310 is not jfet.
>
> > Yes... you are quite right.  Not  sure where I got 'JFET' input from?
>
> ** 1nA input bias current gives one that sort of impression.
>
>  Seems to be using the same "super gain"  NPN transistors for the inputs as
> the LM308 does.
>
>  Amazing stuff for ICs released in the late 1960s.

Bob Widlar was amazing.

http://jove.eng.yale.edu/pipermail/eas-info/2003/000440.html

--
Bill Sloman, Nijmegen
From: JW on 9 Nov 2009 05:51
On Sat, 07 Nov 2009 16:22:42 -0500 Jim Flanagan <jflan(a)tampabay.rr.com>
wrote in Message id: <4af5e523$0$4967$9a6e19ea(a)unlimited.newshosting.com>:

>
>I need a replacement for this device in an 8pin dip package. Does
>anyone have an extra
>they want to sell or barter? These a unity gain, Jfet, buffers. Mine
>is being used in a sample
>and hold circuit that bit the dust. I'm trying to not have to kludge a fix.

NTE crossrefs to a NTE924
http://www.nteinc.com/

$15 at Mouser (ouch)
From: Rich Grise on 9 Nov 2009 16:08
On Sun, 08 Nov 2009 08:36:39 +1000, David Eather wrote:
> Jim Flanagan wrote:
>> I need a replacement for this device in an 8pin dip package. Does
>> anyone have an extra
>> they want to sell or barter? These a unity gain, Jfet, buffers. Mine
>> is being used in a sample
>> and hold circuit that bit the dust. I'm trying to not have to kludge a
>> fix.
>
> It looks like (you better check if you use this idea) that an TL071 (jfet
> inputs) would slot in very well if you can live with the reduced bandwidth
> (3MHz vs 20MHz) and slew rate (13V/uS vs 40V/us)

The LM110/310 is a follower - i.e., unity gain, so if you used an opamp,
you'd have to add a clooge to strap it down to unity gain.

Doesn't have to be a _big_ clooge, if it's a one-off; just lash up a
feedback resistor somewhere near the chip, or maybe even just short
the output to the "-" input.

<anecdote>
One time, my engineer and I were musing about a circuit - he said,
"A zero gain inverter? What would you use a zero gain inverter for?"
I said, "virtual ground." He went, "Ah." and went away happy. :-)
</anecdote>

Hope This Helps!
Rich

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