DAC resolution / availability

[jorgen.bergfors at idg.se]

>>The cheapest solution is to design your own DAC with a simple R network and an
>>op-amp.
>>This way, you can have as many bits as you want in input.
>>Of course, it should take slightly more space on your PCB than a dedicated DAC
>>chip...
>>
>I dont think this is the cheapest way to make a DAC, if you need 12 bit
>accuracy, or even 8.... think about the precision resistors you would >need.... unless
>you have
>laser trimming facilities at home...

You don't need laser trimming. You just need a good DVM, a 200-roll of resistors and some patience.
With 1% metal film resistors, you can normally find 10 resistors out of 200, that are within 1 count on a 4 1/2 digit DVM. That is my experience. 

/Jorgen