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corex
Joined: Mar 02, 2010
Posts: 100
Location: Las Vegas
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 Posted: Tue May 15, 2012 4:03 pm Post subject:
Locate an 8-bit R/2R ladder? |
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I found this 6-bit R/2R ladder by Murata, and they make an 8-bit version but Mouser doesn't carry it. Anyone know where I could find something like this?
For my application, I'd rather not use a parallel DAC. If I can't find an 8-bit ladder I will probably just hand-wire a less precise one with discrete resistors. |
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JingleJoe
Joined: Nov 10, 2011
Posts: 789
Location: Lancashire, England
Audio files: 14
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| Posted: Wed May 16, 2012 2:56 am Post subject:
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I'd just suggest you make your own from resistors, I doubt it will be much less accurate and besides, you can get something like 0.1% tolerance resistors inexpensively, surely that's accurate enough?
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corex
Joined: Mar 02, 2010
Posts: 100
Location: Las Vegas
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| Posted: Wed May 16, 2012 10:01 am Post subject:
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| JingleJoe wrote: | | I'd just suggest you make your own from resistors, I doubt it will be much less accurate and besides, you can get something like 0.1% tolerance resistors inexpensively, surely that's accurate enough? |
That's my backup plan, if I can't find a 10-pin SIP. |
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JovianPyx
Joined: Nov 20, 2007
Posts: 1081
Location: West Red Spot, Jupiter
Audio files: 123
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| Posted: Thu May 17, 2012 1:33 pm Post subject:
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The DAC08 is still available, though it's a DIP not a SIP. It's also available in several SMD (FWIW). It's "parallel" in the same sense that an R2R is parallel - that is, it's not a serial DAC. It needs the 8 wires for the 8 bits you would supply to an R2R. The DAC08 does not contain a set of flipflops, just the analog circuitry required.
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corex
Joined: Mar 02, 2010
Posts: 100
Location: Las Vegas
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| Posted: Fri May 18, 2012 3:13 pm Post subject:
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| JovianPyx wrote: | | The DAC08 is still available, though it's a DIP not a SIP. It's also available in several SMD (FWIW). It's "parallel" in the same sense that an R2R is parallel - that is, it's not a serial DAC. It needs the 8 wires for the 8 bits you would supply to an R2R. The DAC08 does not contain a set of flipflops, just the analog circuitry required. |
This looks like a good suggestion, thanks! I'll read up. I had looked at a couple of parallel 8-bit DACs, but the ones I looked at required a clock signal and so weren't exactly similar to an R/2R. The DAC08 eschews the clock requirement, although it looks like it does add a few passive components for the biasing network. I'll have to order a couple and try it out. |
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Uncle Krunkus
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Joined: Jul 11, 2005
Posts: 4737
Location: Nambucca Heads, Australia
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| Posted: Sat May 19, 2012 5:53 am Post subject:
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I'll second the motion for hand rolled R/2R networks. Everyone of them has it's own unique sound. A bit of resistor testing never hurt anyone!! 
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funkomatic
Joined: Jan 29, 2010
Posts: 1
Location: Texas
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| Posted: Mon May 28, 2012 3:00 pm Post subject:
Re: Locate an 8-bit R/2R ladder? |
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Pretty sure this will do the job: Bourns Part # 4116R-R2R-104. I found it at Direct Components:
http://www.directics.com/search.html |
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corex
Joined: Mar 02, 2010
Posts: 100
Location: Las Vegas
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| Posted: Tue May 29, 2012 3:18 pm Post subject:
Re: Locate an 8-bit R/2R ladder? |
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Thanks for finding that. I found the Bourns datasheet. It looks like "4116R-3-R1/R2" is the relevant diagram? A little confusing, almost like two ladders connected overlapping? But it does seem like you can wire an 8-bit DAC out of it.
That vendor seems to really want a salesman to call you which doesn't give me much hope for a onesy-twosy order. |
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