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trying t build a replacement part for obsolete IC ?

R

robb

Jan 1, 1970
0
hello,
I am trying to find a compatible replacement for an obsolete hard to find
part SN75518N

Afer much searching and reading and learning i thought maybe i could build a
compatible circuit to perform same function as SN75518 ? I think i can
cascade 2 of the MAX6971 to cover what is used on the 75518.

could someone look at these and see if i am on track or lost ?

if lost... can someone give me a landmark ?

use 2 of these
http://datasheets.maxim-ic.com/en/ds/MAX6971.pdf

to build this (-2 od the outputs)
http://focus.ti.com/lit/ds/symlink/sn75518.pdf

to drive a 16 alpha-numeric char VFD (16 segment)


thanks for your time and help,
rob
 
J

J.A. Legris

Jan 1, 1970
0
hello,
I am trying to find a compatible replacement for an obsolete hard to find
part SN75518N

Afer much searching and reading and learning i thought maybe i could build a
compatible circuit to perform same function as SN75518 ? I think i can
cascade 2 of the MAX6971 to cover what is used on the 75518.

could someone look at these and see if i am on track or lost ?

if lost... can someone give me a landmark ?

use 2 of thesehttp://datasheets.maxim-ic.com/en/ds/MAX6971.pdf

to build this (-2 od the outputs)http://focus.ti.com/lit/ds/symlink/sn75518.pdf

to drive a 16 alpha-numeric char VFD (16 segment)

thanks for your time and help,
rob

Try this instead:

http://www.allegromicro.com/en/Products/Part_Numbers/6818/index.asp
 
L

legg

Jan 1, 1970
0
hello,
I am trying to find a compatible replacement for an obsolete hard to find
part SN75518N

Afer much searching and reading and learning i thought maybe i could build a
compatible circuit to perform same function as SN75518 ? I think i can
cascade 2 of the MAX6971 to cover what is used on the 75518.

could someone look at these and see if i am on track or lost ?

You're getting side-tracked. Replace the part using the previously
recommended vendor and put the machine back together, before you get
run over by a pie wagon.

Purchase a spare, if you suspect peripheral involvment in the original
failure.

RL
 
R

robb

Jan 1, 1970
0
legg said:
You're getting side-tracked. Replace the part using the previously
recommended vendor and put the machine back together, before you get
run over by a pie wagon.
Thanks for perspective,

I thought i might be but the parts are so difficult to get... if you are not
ordering $ 300 - 500 of stuff then the chip brokers of obsolete parts (and
there are lots of the chips out there) do not want to talk to you.

so i try to find solutions i can get as end udser like Mouser/Digikey/Arrow
etc

thanks again for advice,
robb
 
R

robb

Jan 1, 1970
0
Mark Zenier said:
See if the Allegro still makes the UCN-5818. (With various suffixes).
Sprague Semi.(now Allegro) said that it was a replacment for the
SN75518.

Mark Zenier [email protected]
Googleproofaddress(account:mzenier provider:eskimo domain:com)
thanks Mark,

perfect suggestion if that chip were not as difficult to buy as the
SN75518N. All those chips exist out there when i do search for them the
SN75518N,UCN5818N,UCN6818 etc i just can not purchase them as they are
stocked by huge chip warehouses and they only deal through brokers and the
brokers only deal with minimum orders of $300-500

so i try to find solutions i can buy
thanks again for your help,
robb
 
R

robb

Jan 1, 1970
0
J.A. Legris said:

Thank Joe,

i have same reply as for others...
Perfect suggestion if that chip was not as difficult to get as the SN75518N
all those chips are availbale through brokers if you are spending $300+
dollars otherwise they do not want to help.
but still a perfect suggestion

so that is reason i was trying to find an alternate solution with parts i
can actually buy.

thanks again for help,
robb
 
J

John Fields

Jan 1, 1970
0
Thank Joe,

i have same reply as for others...
Perfect suggestion if that chip was not as difficult to get as the SN75518N
all those chips are availbale through brokers if you are spending $300+
dollars otherwise they do not want to help.
but still a perfect suggestion

so that is reason i was trying to find an alternate solution with parts i
can actually buy.

---
You can actually buy an Allegro A6818SEP-T from Digi-Key for 5.06
USD and if you want more than one, they have 3031 in stock:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=620-1094-ND

It appears Arrow also has them:

http://app.arrownac.com/aws/pg_webc?s=P
 
M

Mark Zenier

Jan 1, 1970
0
.... ....
perfect suggestion if that chip were not as difficult to buy as the
SN75518N. All those chips exist out there when i do search for them the
SN75518N,UCN5818N,UCN6818 etc i just can not purchase them as they are
stocked by huge chip warehouses and they only deal through brokers and the
brokers only deal with minimum orders of $300-500

Random suggestions: Jameco, JDR Microdevices, B&D Enterprises,
(The mail/web order specialty distributors that are small order friendly
and stock some surplus/chip pulls/older inventory). There's also
places like Rochester Electronics who specialize in the discontinued
parts but often deal with only mil-spec stuff ($$$$).

Your Milage may vary, I have not spent the time to see if they have any.

Also check out the thread "Obselete Devices" in Sci.electronics.design.
one of the regulars has set up some sort of custom Google search that
weeds out those parts brokers with imaginary inventory.

Mark Zenier [email protected]
Googleproofaddress(account:mzenier provider:eskimo domain:com)
 
R

robb

Jan 1, 1970
0
John Fields said:
SN75518N

---
You can actually buy an Allegro A6818SEP-T from Digi-Key for 5.06
USD and if you want more than one, they have 3031 in stock:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=620-1094-ND

It appears Arrow also has them:
http://app.arrownac.com/aws/pg_webc?s=P
JF
Well John, how embarassing :}?

but, i 'd rather be embarassed with chip than honored and chipless.
as it turns out i was looking for ucn6818 like the ucn5818 so a partial
6818sep helped

so do you have a idea for simple conversion of the PLCC pkg to DIP-40
an adapter perhaps ???

thanks for chimeing in,
robb
 
J

John Fields

Jan 1, 1970
0
Well John, how embarassing :}?

but, i 'd rather be embarassed with chip than honored and chipless.
as it turns out i was looking for ucn6818 like the ucn5818 so a partial
6818sep helped

so do you have a idea for simple conversion of the PLCC pkg to DIP-40
an adapter perhaps ???

---
Probably, but they're usually hideously expensive.

Was the 75518 soldered in or socketed?
 
P

Peter

Jan 1, 1970
0
hello,
I am trying to find a compatible replacement for an obsolete hard to find
part SN75518N

Afer much searching and reading and learning i thought maybe i could build a
compatible circuit to perform same function as SN75518 ? I think i can
cascade 2 of the MAX6971 to cover what is used on the 75518.

could someone look at these and see if i am on track or lost ?

if lost... can someone give me a landmark ?

use 2 of thesehttp://datasheets.maxim-ic.com/en/ds/MAX6971.pdf

to build this (-2 od the outputs)http://focus.ti.com/lit/ds/symlink/sn75518.pdf

to drive a 16 alpha-numeric char VFD (16 segment)

thanks for your time and help,
rob
Hi Rob,
why give up SN75518N? what is the quantity you need for your project?
if it is below 30k, you can continune to use it. we can support you at
this item.

best regards,
Peter
[email protected]
www.expertonic.com
 
A

Al

Jan 1, 1970
0
robb said:
soldered
robb

FWIW, I have heard for people emulating obsolete chips with
microcontrollrs or PALs. I wouldn't be surprised if that's what you
would get if you ordered a significant number of them from an Asian
supplier.

Al
 
R

robb

Jan 1, 1970
0
Al said:
FWIW, I have heard for people emulating obsolete chips with
microcontrollrs or PALs. I wouldn't be surprised if that's what you
would get if you ordered a significant number of them from an Asian
supplier.

Al

you know after doing all this searching for the chip i was going to ask a
question along those lines but then i thought i would get some feedback like

yea you can with $900 chip burner and $250 programming software, couple of
months microcode/controler development experience and a couple of weeks of
testing and you better buy a tube of chips in case you fry a couple and then
you need a testing board and setup ........

so i did not ask :)
robb
 
G

Gary Tait

Jan 1, 1970
0
so do you have a idea for simple conversion of the PLCC pkg to DIP-40
an adapter perhaps ???

To build?

If there is room;
An adequate sized perf board with two rows od common .1" headers, perhaps
with mating sockets on the one board. Also on the perf board woth be a PLCC
socket with through hole .1" pins, the socket point-to-point wired to the
headers. A little less witing, and you can use a surface mount socket, or
solder the chip down, if you fab a PCB.
 
P

-=Punkrat=-

Jan 1, 1970
0
Shenzhen, China?!?!
I think Rob wants *REAL* SN75518N's......

We have a US supplier with 200 pcs SN75518N in stock.
Drop me a line at work if that would help
[email protected] remove the XXX

About 90% of the product sold from Shenzhen are duds, bad pulls,
counterfeits or sub-standard remarks.

If you order from China you're better off to have your supplier just
steal your money up front, that way you save the Fed Ex charges on the
garbage they ship.

..
 
R

robb

Jan 1, 1970
0
-=Punkrat=- said:
We have a US supplier with 200 pcs SN75518N in stock.
Drop me a line at work if that would help
[email protected] remove the XXX

About 90% of the product sold from Shenzhen are duds, bad pulls,
counterfeits or sub-standard remarks.

If you order from China you're better off to have your supplier just
steal your money up front, that way you save the Fed Ex charges on the
garbage they ship.
Hi,
Thanks for the offer to help jeff. Thats great !
but i just ordered the compatible replacements from digi-key.
I will try to get that working first, partly for challenge/experience of
fitting a 44-plcc into my 40-dip spot as well as making the repair.
However, if the chip turns out to be not so compatible with my old circuit
or i really muck things up then i might surely need to take you up on your
offer.

thanks again for offer (and shenzen heads up) i really appreciate that,
robb
 
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