[sdiy] selecting a semiconductor manufacturer

[phillip m gallo]

Ken,

Your associates are right.  As standard design practice your schem, Gerbers,
Assy DWG's, and BOMs should always be accompanied by an Approved Vendor List
(AVL).

regards,
p

-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of Ken Stone
Sent: Thursday, May 19, 2005 9:12 PM
To: synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] selecting a semiconductor manufacturer


To sum it up from my experience - Chips/transistors from different
manufacturers do differ. Sometimes that difference has no bearing on your
application. Sometimes that difference will make one manufacturer's chip
fail dismally in a situation in which another "thrives". In fact some of my
associates have made the following statement - When writing out a parts
list, the brand name of the semiconductors used MUST be specified.

Ken

>Interesting... being a relative newcomer to analog EE I've always been
>curious about this subject of different IC manufacturers and whether
there's
>any significant differences between them.  Especially since the data sheets
>nearly all look alike for a given legacy part.  I thought I remembered
>reading a comment Bob Pease made in one of his articles or books that "data
>sheets lie" or some such.  So what then can one go by other than
experience,
>or the shared experiences of others?
>
>In the cases where the data sheets are the same across manufacturers, I
>wonder if the masks and materials are *really* all the same as well, and if
>not, if there might not be some slight side effect that a 2nd source part
>might have in a given circuit where the original manufacturer's part would
>work perfectly.  For example, I remember reading on this list that the
>Fairchild 4051 has some potential latch-up issues compared to other
>manufacturers, again, depending on the circuit.
>
>Also, there seems to be some mystery (aka my lack of knowledge!) about the
>original NE5532 (a Phillips part?) and it's sound quality compared to the
>current crop of 2nd source'ers like TI and what not.  I've read that the
>original factory and masks were lost in a fire some years ago and that more
>recent parts (that use copies of copies of masks?) do not sound the same.
>
>And another one is the JRC4558 vs the newer RC4558 parts.  Is this all
snake
>oil??
>
>A big source of confusion for me is that prices for a given part are
usually
>all over the map.  I've noticed that when a part originates with a
>particular manufacturer (say the National LM324) their price is often
higher
>than any other 2nd source parts.  Makes you 2nd guess yourself.
>
>In the end, since I'm not really equipped to make knowledgeable decisions
>between most of these parts, I usually just try to find the lowest
>price-at-quantity for the original manufacturer of a part, and if the 2nd
>source part is more than say 25% cheaper, I'll get the 2nd source.  And
>since I greatly respect the comments of listmembers here I therefore try to
>heed any prior advice on the subject.
>
>Hey Harry, what about those new-old BBDs?  Bet they still sound like s#^t!
>;-)
>
>-George
>
>----- Original Message -----
>From: "James Patchell" <patchell at cox.net>
>To: <synth-diy at dropmix.xs4all.nl>
>Sent: Tuesday, May 17, 2005 8:33 PM
>Subject: Re: [sdiy] selecting a semiconductor manufacturer
>
>
>> I am also dubious about the quality of parts that NTE sells...definitely
>> correct me if I am wrong in my impression...
>>
>> As far as the other in the list...I have never noticed anything
>> significantly different between the major manufacturers.
>>
>>          -Jim
>> ***************************************************************
>> http://www.oldcrows.net/~patchell
>
>
_______________________________________________________________________
Ken Stone   sasami at hotkey.net.au or sasami at cgs.synth.net
Modular Synth PCBs for sale <http://www.blaze.net.au/~sasami/synth/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>



--
No virus found in this incoming message.
Checked by AVG Anti-Virus.
Version: 7.0.322 / Virus Database: 266.11.13 - Release Date: 5/19/05