[sdiy] discrete 3-bit AD converter??

[Scott Gravenhorst]

This is called a "flash ADC".  There's a 3 bit circuit on page
621 of Art of Electronics.  It is implemented as you suggested,
a stack of comparators.  2 bits would have about 1/2 the 
comparators  (7 required for 3 bits).

There are also ICs that do this, Analog Devices comes to mind.

media at mail1.nai.net wrote:
>
>This might be a stupid question, but I'm willing to follow it up with an
>even stupider question :)
>
>I'd like to be able to convert a CV going from 0 to 5 volts into a six
>3-bit binary numbers.  Well, just to illustrate my question, let's just say
>I want four 2-bit numbers to represent one to four volts, such that:
>
>1V = 00
>2V = 01
>3V = 10
>4V = 11
>
>I'm thinking I could do this with a stack of comparators each set to the
>next highest voltage (off of a "totem pole" voltage divider run off of the
>incoming CV), but I'm thinking there must be an easier way that would use
>less chips.  If that is the best way, is there a single CMOS chip (like the
>opposite of an LED segment driver) that will encode it into a binary
>number??  Are there chips with multiple comparators IC's without the extra
>pins for such a purpose??  Basically, I'm trying to devise a way to enable
>a number of logic states with single control voltage.
>
>
>

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