Re: [amsat-bb] KCT/T level chips

[bronson@xxxxxxxxxxxxxx]

Mark Johns wrote:

> Thanks, Bronson.  What cross reference guides do you use for checking.  I
> have a couple around here, but they are so old and out of date that I don't
> trust them to be reliable.  Thanks.

This can be a real sore spot with no complete and definitive answer.  The
industry changes so fast, parts become obselete so quickly... it is the old
throw it away and buy a new one problem.  It cost so mutch to fix it you may
as well buy a new one.  Not only are the parts discontinued but the
information is dropped twice as fast.  In some cases manufacturers drop the IC
like a hot potato because it isn't selling like they hoped.  Along with it
goes all the support.  Your best allie is what's between your ears.  Whatever
you don't give up on your old references!  Like vacuum tube data and cross
references they can be priceless to some.

Motorola, like most manufacturers, has a limited cross reference table in its
data books concerning all of their families of ICs.  Unfortunately Motorola
has been undergoing some re-structureing of its business units and its web
site has suffered.  That means that if you don't have the pertainent data
books, it can be hard to find the cross reference tables.  With a little
digging on their web site you should be able to down load their Selection
Guide which, in the past, has included a limited cross reference table.

Old or new you need to figure out what the beasty is and how it can be used.
Then you need to sift through the schamatic and figure out how it is used in
your particular case.  Much of the substitution work I do is with old
equipment that is not supported by the manufacturer and many of the components
cannot be had for love nor money.  In such cases cross reference tables are of
little value.  I get by using my witts.  With a little reading you can bring
yourself up to speed on some of the IC families so that you can choose similar
but not exact replacements for many linear and digital functions.  Some
modifications may need to be done to the target equipment but those mods may
not be particularly radical.

The real trick is to figure out what you don't know and then take steps to
aquire that info.  From there you can solve most any substitution problem.
Persistance pays.  I've tried A... I've tried B.... keep going... one way or
another you can work it out.  After all someone had to design the fool thing
so it can't be a complete mystery.  Although some systems work despite their
designers best efforts... ha ha ha....

Doing so can breath new life into old equipment that would otherwise lay idle
for want of a $2 IC.  In my field of instramentation this can be a buget saver
since a new piece of equipment may cost thousands or tens of thousands of
dollars.  I can save a years salary by keeping one or two peices of equipment
running which otherwise would have to be replaced.

I also find myself refering to ICMaster as others have mentioned.  I am also
blessed with a few old (1980s and 1970s) data books and catalogs from various
manufacturers, still hanging around my office.  Many of the Manufacturers web
sites are limited to the last ten years as far as compatability goes.  Some
web sites are almost useless as far as cross references go.  I have started
searches for parts on Motorola's web site that come up blank on parts I know
are still in production!!!  Finding info can be reeeeeal frustrating.

I spend a good deal of time down loading pdf files of data sheets, selection
guides, application notes...etc.  The application notes can be especialy fruit
full.  Analog Devices, HP, Motorola, National, NEC, Fairchild, Microchip,
Burr-Brown, Allegro, Philips... they all have libraries of good info that is
available on their web sites.  NASA has some good stuff on systems...
batteries as well.  If you keep digging you can generaly find what you need.
What you can't find there you can find in your local library through
inter-library loan.

Don't give up... hardware is realy cool... you just have to get to know it a
bit.

>
> --
> Mark D. Johns, Cedar Falls, Iowa -- K0MDJ (EN32sm)
>               http://pages.cfu.net/~mjohns/index.html
>  "Heaven goes by favour.  If it went by merit, you would
>     stay out and your dog would go in." -- Mark Twain
>
> Bronson wrote:
>
> > As is often the case with Motorola they substitute MC for the first
> > letters of a device number.  They also sometimes pack a 1 (one) in there
> > as well.  Especially with the 40xxx CMOS family.  In this case the 1488
> > and 1489 are pin compatible and perform the same function.
> >
> > There are no hard and fast rules in device packaging or marking.  Always
> > check and double check.  Some manufacturers make substitute devices
> > whose numbering has nothing in common with the original device.
> >

--
/***************************************
Bronson Crothers
17 Charles St.
Orono  ME  04473

Phone: 207 866 0405
Fax:.....207 866 0405

Radio Call: N1ZAQ

--... ...--

Email: bronson@eece.maine.edu
**************************************/


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