[sdiy] Re: Inexpensive 16 bit DAC?

[Scott Gravenhorst]

It seems to me that the analog switches are overkill and could be replaced by
a CMOS inverter gate (or buffer) per bit.  It looks to me that the switches
are simply providing a solid 12 volts or a solid ground to one end of each
resistor.  I'm really not sure why a 4069UB  wouldn't work as well at less
than half the part count.  Ok, you would want to do TTL to CMOS level
conversion, but still it would be fewer parts.  A 4066 is a bidirectional
device but you are using it as a unidirectional device which is why I think a
4069UB design would work just as well.  The 4069 would be powered from +12
and ground, the output of each gate hits the resistor.  If the whole thing
were powered by +5 and ground, it would be even simpler.

Is there some advantage the 4066 provides that I'm not seeing?

"Ray Wilson" <raywilson at comcast.net> wrote:
>
>Here is a DAC with CD40106 and CD4066 chips. I have demo'd 4 bits but you 
>could go as many as you had patience to build.
>
>Ray
>
>----- Original Message ----- 
>From: "KA4HJH" <ka4hjh at gte.net>
>To: "Bob Weigel" <sounddoctorin at imt.net>
>Cc: <synth-diy at dropmix.xs4all.nl>
>Sent: Wednesday, April 27, 2005 3:24 AM
>Subject: Re: [sdiy] Re: Inexpensive 16 bit DAC?
>
>
>> >Usually you have to tell them that you are like working on something
>>>where you might actually BUY some chips to get samples...or does Analog
>>>just hand them out to anyone?  I could have been getting samples all
>>>along for the project I'm working on from microchip but I haven't even
>>>had time to ask for them and I feel bad doing it because we really don't
>>>need them except that that company is out of money I guess so maybe we
>>>do :-). -Bob
>>
>> They may ask you a few simple questions, like "What's this for?" or 
>> "What's
>> the goal of the project?". So you just answer "experimental interface
>> design for musical instrument" or something lofty you've daydreamed about
>> but will probably never get around to. Talk like a junior in college--half
>> clueless but you know some buzzwords.
>>
>> Maxim is another one you want to hit up...they've got good stuff...
>>
>> -- 
>>
>> Terry Bowman, KA4HJH
>> "The Mac Doctor"
>>
>> "You'd PAY to know what you REALLY think"--Dobbs 
>
>

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-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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