[sdiy] 4 bit D2A converter

[Ben Lincoln]

If you have enough fanout in whatever you're feeding it, would it work 
to hook up each actual input line to two of the pins on the D2A 
converter, like this?

Bits 1 + 5
Bits 2 + 6
Bits 3 + 7
Bits 4 + 8

That is, in pseudocode:

i2 = i1 + (i1 << 4);

If I've done the logic right, that means for each step on your 4-bit 
"virtual input", you are incrementing the (8-bit) "real input" by 17, 
and you still end up with input values for your D2A converter that are 
in the range 0-255 (because 255 = 17 * 15), with linear scaling.

On 2011-10-01 21:29, 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?
>
>
> thanks
>
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