[sdiy] 4 bit D2A converter

[Tim Ressel]

Mouser 81-RGSD8L203G
4-bit R2R ladder, 20K

$1.10

Or you can just get some resistors and make your own. I prefer the packaged version. Smaller and lazier. 


--Tim (lazy sob) Ressel



----- Original Message -----
From: Tom Wiltshire <tom at electricdruid.net>
To: dan snazelle <subjectivity at hotmail.com>
Cc: synthdiy diy <synth-diy at dropmix.xs4all.nl>
Sent: Sunday, October 2, 2011 9:21 AM
Subject: Re: [sdiy] 4 bit D2A converter


On 2 Oct 2011, at 05:29, dan snazelle wrote:

> I am putting something together which requires a 4-bit D2A.
> 
> is there a way to use an 8 bit D2A chip somehow and maybe just ground the lowest least significant bits?
> 
> or would an R2R be the way to go for so few bits?

I'd definitely look at either R2R or weighted resistor values for so few bits. A whole DAC chip seems like overkill.

One possibility would be to use an op-amp inverting mixer, with four weighted inputs (5K, 10K, 20K, 40K?). I know logic voltages vary a bit, but it'd be close enough for four bits.

HTH,
Tom

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