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Guest
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 Posted:
Sat Jan 08, 2005 10:39 am Post subject:
Need help finding replacement for obselete IC chip |
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I am working on a circuit that calls for a MM5837N noise generating IC chip.
This is an obselete chip and I need to find a chip that can take its place.
Any help in locating an alternate chip would be great.
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John Woodgate
Guest
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| Posted:
Sat Jan 08, 2005 2:36 pm Post subject:
Re: Need help finding replacement for obselete IC chip |
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I read in sci.electronics.design that elehman1@columbus.rr.com wrote (in
<QtJDd.65783$mA3.13229@fe2.columbus.rr.com>) about 'Need help finding
replacement for obselete IC chip', on Sat, 8 Jan 2005:
| Quote: | I am working on a circuit that calls for a MM5837N noise generating IC chip.
This is an obselete chip and I need to find a chip that can take its place.
Any help in locating an alternate chip would be great.
You may not find a chip. There are many ways of generating noise. What |
bandwidth do you want?
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk |
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Wim Ton
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| Posted:
Sat Jan 08, 2005 5:12 pm Post subject:
Re: Need help finding replacement for obselete IC chip |
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| Quote: | I am working on a circuit that calls for a MM5837N noise generating IC
chip.
This is an obselete chip and I need to find a chip that can take its
place. |
According to google, it still seems available form various sources.
An alternative may be to use an 8 pin uC like the ATTiny11 or a similar PIC.
The only change is that you have to insert it the wrong way round and patch
the Gnd to pin 8 (the MM5837N has an unusual pinout)
Wim
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Ed Price
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Guest
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| Posted:
Sat Jan 08, 2005 7:56 pm Post subject:
Re: Need help finding replacement for obselete IC chip |
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Thanks for the info.
"Ed Price" <edprice@cox.net> wrote in message
news:IaRDd.15928$yW5.14512@fed1read02...
&imageField.x=34&imageField.y=12
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Clive Tobin
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Sun Jan 09, 2005 12:37 am Post subject:
Re: Need help finding replacement for obselete IC chip |
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A much better white noise source can be made with lots of stages of
jellybean shift register, with two taps XOR'd back to the data input,
with an external clock. The MM5837 is only 17 stages tapped at 14 so it
has an audibly repeating pattern.
The ARG (Audio Reference Generator) we used to make used 33 stages of
SR with taps at 20 and 33 fed back. This gives white noise that does
not audibly repeat (I forget the period, it was minutes or hours.) The
clock was I think about 100 kHz.
The noise generator in Dolby Stereo alignment equipment uses 49 stages
with taps at 44 and 49 fed back. With a 766 kHz clock, the repeat time
is 204,000 hours so you would be *very* hard pressed to hear a pattern.
I have often idly wondered how the designer comes up with the taps for
this service.
Cheers, Clive Tobin
www.tobincinemasystems.com |
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Hal Murray
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| Posted:
Sun Jan 09, 2005 1:44 am Post subject:
Re: Need help finding replacement for obselete IC chip |
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| Quote: | I have often idly wondered how the designer comes up with the taps for
this service.
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Mathematicians collect them.
There is a small table in Art of Electronics. Xilinx has a much
bigger table in one of their app-notes. Google for LFSR.
--
The suespammers.org mail server is located in California. So are all my
other mailboxes. Please do not send unsolicited bulk e-mail or unsolicited
commercial e-mail to my suespammers.org address or any of my other addresses.
These are my opinions, not necessarily my employer's. I hate spam. |
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Clive Tobin
Guest
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| Posted:
Sun Jan 09, 2005 2:55 am Post subject:
Re: Need help finding replacement for obselete IC chip |
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Found it! It is table 3 of
http://direct.xilinx.com/bvdocs/appnotes/xapp052.pdf covering all
combinations from 3 to 168 stages.
Thanks. Not that I'll ever know how they derive it, or need to use it
again... |
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Richard Crowley
Guest
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| Posted:
Sun Jan 09, 2005 3:21 am Post subject:
Re: Need help finding replacement for obselete IC chip |
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<elehman1@columbus.rr.com> wrote ...
| Quote: | I am working on a circuit that calls for a MM5837N noise generating IC
chip.
This is an obselete chip and I need to find a chip that can take its
place.
Any help in locating an alternate chip would be great.
|
Is there something so special that you MUST use an obsolete (and
likely ridiculously expensive) chip for such a generic function? |
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Oppie
Guest
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| Posted:
Tue Jan 18, 2005 8:23 pm Post subject:
Re: Need help finding replacement for obselete IC chip |
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I used a similar chip that was a bit more flexible, the AMI S2688. It had an
external clock option so I could shift the noise spectrum to my needs.
Device is also obsolete but was pin compatible with the 5837. I found 5 of
them in the back room if there is any interest. Finding a data sheet could
be a challenge though.
Plug-in solutions are great but if I had to do it again, would do it in a
PIC or AVR.
Oppie
<elehman1@columbus.rr.com> wrote in message
news:QtJDd.65783$mA3.13229@fe2.columbus.rr.com...
| Quote: | I am working on a circuit that calls for a MM5837N noise generating IC
chip.
This is an obselete chip and I need to find a chip that can take its
place.
Any help in locating an alternate chip would be great.
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