Searching \ for '[EE] Where have all the 7490's gone?' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=where+all+7490s
Search entire site for: 'Where have all the 7490's gone?'.

Exact match. Not showing close matches.
PICList Thread
'[EE] Where have all the 7490's gone?'
2006\06\28@182623 by PicDude

flavicon
face
Why have all the 74xx90's (decade counters) disappeared suddenly?  My usual
sources (Digikey & Mouser) are claiming that they're discontinued/obsolete.  
Anyone know where I can get just 10-12 of these in SOIC packaging?  Have some
PCB's already made from over a year ago that I need these for, so it's not a
simple matter of choosing a different part.

Cheers,
-Neil.

2006\06\28@185108 by Harold Hallikainen

face picon face
I'm finding them at various places in LS and HC. Try
http://www.findchips.com .

Harold



{Quote hidden}

> -

2006\06\28@185944 by Bob Blick

face picon face

> Anyone know where I can get just 10-12 of these in SOIC packaging?

Jameco has them (74LS90M) in stock, part # 198539

Cheers,

Bob


2006\06\29@015316 by Wouter van Ooijen

face picon face
> Why have all the 74xx90's (decade counters) disappeared
> suddenly?  My usual
> sources (Digikey & Mouser) are claiming that they're
> discontinued/obsolete.  

For which value of xx?

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


2006\06\29@041104 by Alan B. Pearce

face picon face
>Why have all the 74xx90's (decade counters) disappeared suddenly?
>My usual sources (Digikey & Mouser) are claiming that they're
>discontinued/obsolete. Anyone know where I can get just 10-12 of
>these in SOIC packaging?  Have some PCB's already made from over
>a year ago that I need these for, so it's not a simple matter of
>choosing a different part.

Hmm, you say which particular xx90 you are using, but if it was the HC390,
then look at Philips. I was browsing their site the other day and they had a
HC590 that looked like a reasonably new product ...

http://www.standardics.philips.com/products/logic/


2006\06\29@073357 by olin piclist

face picon face
> Why have all the 74xx90's (decade counters) disappeared
> suddenly?

Probably because nobody uses them anymore.  Even a very slow micro can count
decades.


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2006\06\29@091416 by Russell McMahon

face
flavicon
face
>> Why have all the 74xx90's (decade counters) disappeared
>> suddenly?

> Probably because nobody uses them anymore.  Even a very slow micro
> can count
> decades.

That brings back memories. I long ago spent many a happy hour playing
with 7490s and their ilk. They are, indeed, obsolete *BUT*, even for
the standard original TTL part, with an A input capability of 32 MHz
and minimum A input pulse width of 15 nS there are still some things
you can do with a TTL 7490 that you may have trouble doing with some
very slow, or even not totally slow, micros. Some of the newer
families are substantially faster and would allow input frequencies
and pulse widths unavailable on the majority of  8 bit processors.

       Ye Olde TTL
http://focus.ti.com/lit/ds/symlink/sn74ls90.pdf

The above data sheet covers TTL and LSTTL parts and does not seem to
distinguish between them or the above parameters.

The 74HC93 (and quite possibly therefore the 90 as well)( has a
maximum clock frequency of about 100 MHz. (downhill with the wind
behind it on bank holidays in winter)(wet / dead fish optional). ALS
and F and ... may be faster again.



       Russell


2006\06\29@094835 by Alan B. Pearce

face picon face
>That brings back memories. I long ago spent many a
>happy hour playing with 7490s and their ilk. They are,
>indeed, obsolete *BUT*, even for the standard original
>TTL part, with an A input capability of 32 MHz and
>minimum A input pulse width of 15 nS there are still
>some things you can do with a TTL 7490 that you may have
>trouble doing with some very slow, or even not totally
>slow, micros. Some of the newer families are substantially
>faster and would allow input frequencies and pulse widths
>unavailable on the majority of  8 bit processors.

Exactly - that speed is faster than the timer input on a dsPic ... like
about twice as fast, maybe a bit more, depending on how you read the
with/without prescaler spec.

2006\06\29@142252 by William Chops Westfield

face picon face

On Jun 29, 2006, at 6:04 AM, Russell McMahon wrote:

>       Ye Olde TTL
> http://focus.ti.com/lit/ds/symlink/sn74ls90.pdf
>
There is another TI page (Logic selector guide?) that claims
1) the 74xx90 only exists as 7490 and 74ls90 (no HC, etc)
2) The 7490 is obsolete, but the 74ls90 is "active", and should
   still be available...
(Other vendors may vary, of course.)

I suspect that the distributer problems the OP is having stem
from distributers getting rid of the ls series entirely.

BillW

2006\06\29@235811 by TOMTOM

picon face
As far as I know, the 7490 has gone the way of many 7400 series chips: bye
bye :-)  Some years ago I designed 7490's in and later designed the
MCS14510B in as a U/D decade counter.  Now, a lot of designs are done with
Xilinx or equivalent.  But I think the 4510 is still available.  However, it
is not pin compatible.  If you need pin compatible you may need to go to
some place like "part Miner" on the web.
{Original Message removed}

2006\06\30@014326 by PicDude
flavicon
face
Nice resource -- thanks.
-Neil.


On Wednesday 28 June 2006 17:51, Harold Hallikainen wrote:
{Quote hidden}

2006\06\30@014402 by PicDude

flavicon
face
Recently had a bad experience with Jameco, so I'll avoid them if possible.
-Neil.


On Wednesday 28 June 2006 17:59, Bob Blick wrote:
> > Anyone know where I can get just 10-12 of these in SOIC packaging?
>
> Jameco has them (74LS90M) in stock, part # 198539
>
> Cheers,
>
> Bob

2006\06\30@030250 by PicDude

flavicon
face
This was for a PIC-based project that measures frequency (among other things).  
On some sensors, the output frequency was higher than the PIC could handle,
so a quick 7490-based div-by-10 did the job nicely.

-Neil.


On Thursday 29 June 2006 06:35, Olin Lathrop wrote:
> > Why have all the 74xx90's (decade counters) disappeared
> > suddenly?
>
> Probably because nobody uses them anymore.  Even a very slow micro can
> count decades.
>
>
> ******************************************************************
> Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
> consultant in 2004 program year.  http://www.embedinc.com/products

2006\06\30@074254 by olin piclist

face picon face
PicDude wrote:
> Recently had a bad experience with Jameco, so I'll avoid them if
> possible.

Could you elaborate please?  I use Jameco a lot and am generally satisfied.
I consider them the best source for lab stock parts (*), although I'm
careful about using them for production since you don't always know what
manufacturere you'll get.  In the many years I've been ordering from them, I
can only remember twice where an order got screwed up.  Both times something
I had ordered and paid for was missing, and both times they sent out the
additional parts based only on my say-so over the phone that I hadn't
received them.  In other words my experience is that they screw up rarely,
and promptly take the appropriate corrective action when they do.


* There are some notable exceptions.  Crystals and PIC come to mind
immediately.  For some reason, they have a very limited selection of
crystals for parallel resonant application, and their PIC prices are
(uncharacteristically) out of line.  Use DigiKey for the former and
buy.microchip.com for the latter unless you can buy over 1000 at a time.


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2006\06\30@125542 by TOMTOM

picon face
One of the reasons why the 7490 has become obsolete (scarce if you prefer)
is because they are a high current, high heat device compared with the newer
technology (CMOS, etc.).  The 74LS Series is an improvement in speed but
still relatively high current and heat.  Many designers are considering low
voltage devices as a result of the increased demand for portable, battery
powered stuff.  I would thing that newer designs for production quantities
would consider alternatives to the 74xx or 74LSxx devices.  That being said,
it is just MHO.

{Original Message removed}

2006\06\30@143205 by Peter Todd

picon face
On Fri, Jun 30, 2006 at 07:44:17AM -0400, Olin Lathrop wrote:
> * There are some notable exceptions.  Crystals and PIC come to mind
> immediately.  For some reason, they have a very limited selection of
> crystals for parallel resonant application, and their PIC prices are
> (uncharacteristically) out of line.  Use DigiKey for the former and
> buy.microchip.com for the latter unless you can buy over 1000 at a time.

How's your experiences with buy.microchip.com been? I've nearly bought
stuff from them a few times, whenever digikey ran out of whatever chip I
really had wanted to use, but each time digikey seems to magically have
a dozen more in stock right when I need them.

FWIW I would never have a need to buy more of about 100 PICs at a time,
and usually no more than 10-20.

Of course, customs could be a killer, me being in Canada. Couriers
always seem to charge a lot of fees for brokerage to say the least.

--
spam_OUTpeteTakeThisOuTspampetertodd.ca http://www.petertodd.ca

2006\06\30@144708 by olin piclist

face picon face
Peter Todd wrote:
> How's your experiences with buy.microchip.com been?

Just fine.  They usually have as good or better prices than distributors for
small volumes of PICs.  The other nice thing is that the whole Microchip
product line is available, not just the part the distributor felt like
carrying.


******************************************************************
Embed Inc, Littleton Massachusetts, (978) 742-9014.  #1 PIC
consultant in 2004 program year.  http://www.embedinc.com/products

2006\06\30@151007 by Wouter van Ooijen

face picon face
>> How's your experiences with buy.microchip.com been?
>
> Just fine.  They usually have as good or better prices than
> distributors for
> small volumes of PICs.  The other nice thing is that the
> whole Microchip
> product line is available, not just the part the distributor felt like
> carrying.

Their prices for my quantities (25 .. 500) are well below the
distributor I used to deal with. And unlike foreign sellers I officially
buy from a microchip branch in my country, which makes VAT and customs
(otherwise a nuisance) a non-issue.

My only complaint is about their handling of credit card payment claims
in replation to backorders: the first claim the total amount, then
charge only what they ship. This leaves the (total!) claim active, which
reduces the amount I can use for other CC purchases.

And a nitty-gritty: you can choose your country by flag, but the Dutch
and Luxemburg flags are almost indistinguishable...

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


2006\06\30@173241 by Peter Todd

picon face
On Fri, Jun 30, 2006 at 09:11:04PM +0200, Wouter van Ooijen wrote:
> >> How's your experiences with buy.microchip.com been?
> >
> > Just fine.  They usually have as good or better prices than
> > distributors for
> > small volumes of PICs.  The other nice thing is that the
> > whole Microchip
> > product line is available, not just the part the distributor felt like
> > carrying.
>
> Their prices for my quantities (25 .. 500) are well below the
> distributor I used to deal with. And unlike foreign sellers I officially
> buy from a microchip branch in my country, which makes VAT and customs
> (otherwise a nuisance) a non-issue.

Just called them up myself actually. Aparently all "silicon" is shipped
direct from Thailand, however it's shipped "DVP" (duty something paid)
so in my case I should only have to pay the standard GST/PST plus a $22
shipping/handling/everything fee. No silly $50 brokarage fees.

Not bad if you can put together a decent-sized order.

> My only complaint is about their handling of credit card payment claims
> in replation to backorders: the first claim the total amount, then
> charge only what they ship. This leaves the (total!) claim active, which
> reduces the amount I can use for other CC purchases.

Good point there, wouldn't do much good for me, with my very, very low
student credit limit.

> And a nitty-gritty: you can choose your country by flag, but the Dutch
> and Luxemburg flags are almost indistinguishable...

Looking at that select your country page reminds me of how few novel
ideas there are in flag design... Must be the european standard bearers
tradition or something.

--
.....peteKILLspamspam@spam@petertodd.ca http://www.petertodd.ca

2006\06\30@222941 by Rich

picon face
I can identify with that challenge. :o(  I have a product still in the field
that uses an ICL7109 A/D converter. Some customers keep their products as
long as they are working and it is good will to keep supporting them.  I
have made some pluggable daughter boards on occasion, and sent them off for
the customer to plug them in, in place of a chip, because the customer did
not want to upgrade. I suppose I could have said "have to upgrade."  But I
would not feel comfortable with that. You are fortunate to still find the
7490.  

{Original Message removed}

2006\06\30@235451 by Harold Hallikainen

face picon face
I MIGHT have some ICL7109s. I designed them into a product about 20 years
ago and may still have some. Let me know if you want me to look for them.

Harold


{Quote hidden}

> {Original Message removed}


'[EE] Where have all the 7490's gone?'
2006\07\01@032840 by Wouter van Ooijen
face picon face
> I can identify with that challenge. :o(  I have a product
> still in the field that uses an ICL7109 A/D converter.

My supplier still has those (DIP).

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


2006\07\01@032842 by Wouter van Ooijen

face picon face
> Looking at that select your country page reminds me of how few novel
> ideas there are in flag design... Must be the european
> standard bearers tradition or something.

IIRC all countries that were at some point in history at some side in
some war selected red/blue/white in some combination and orientation.

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


2006\07\01@114023 by Gerhard Fiedler

picon face
Wouter van Ooijen wrote:

>> Looking at that select your country page reminds me of how few novel
>> ideas there are in flag design... Must be the european standard bearers
>> tradition or something.
>
> IIRC all countries that were at some point in history at some side in
> some war selected red/blue/white in some combination and orientation.

Germany: black, red, gold?
Brazil (yes, they participated, reluctantly, in WW2): green, yellow, blue?

I'm sure there are many more... there have been so many wars. Also, quite
often the colors were chosen (long) before the participation in a war; how
did you mean this to work?

Gerhard

2006\07\01@160152 by Wouter van Ooijen

face picon face
> > IIRC all countries that were at some point in history at
> some side in
> > some war selected red/blue/white in some combination and
> orientation.
>
> Germany: black, red, gold?
> Brazil (yes, they participated, reluctantly, in WW2): green,
> yellow, blue?
>
> I'm sure there are many more... there have been so many wars.
> Also, quite
> often the colors were chosen (long) before the participation
> in a war; how
> did you mean this to work?

I was referring to one specific conflict, but I don't recall exactly
which. Probably one of the anti-spanish leagues in the 17th or 18th
century.

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu


More... (looser matching)
- Last day of these posts
- In 2006 , 2007 only
- Today
- New search...