Analog to Digital Converter

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Hi guys i am in the process of trying to figure out how and where to
start to build a Analog to digital converter for a project. I have
done some research and it seems that at the basic level its nothing
more that a pulse oscillator circuit followed by a comparator. The
specification i must stick with are :
1. max input freqeuncy 100khz
2. successive approx type with best guess centering
3. max bits are eight
4. max error of 1% at output

If anyone can direct me to some circuit diagrams or information, i
would appreicate it.

thanks
peter

 

[Dan Coby]

Hi guys i am in the process of trying to figure out how and where to
start to build a Analog to digital converter for a project.

This looks like another example of someone asking for help with their
homework assignment.

 

[Chris]

Hi guys i am in the process of trying to figure out how and where to
start to build a Analog to digital converter for a project. I have
done some research and it seems that at the basic level its nothing
more that a pulse oscillator circuit followed by a comparator. The
specification i must stick with are :
1. max input freqeuncy 100khz
2. successive approx type with best guess centering
3. max bits are eight
4. max error of 1% at output

If anyone can direct me to some circuit diagrams or information, i
would appreicate it.

thanks
peter

Hi, Peter. Actually, you're supposed to put a dab of quicksilver in
the loaf before you set it afloat. It stops in the newsgroup right
over the answer to the homework question. All ah see heer is a plain
loaf. ;-)

Not that you really need this, but you might want to look at Analog
Devices Appnote AN-289. No link -- as a bonus, you'll have to look it
up yourself.

If it "seems that at the basic level its nothing more that a pulse
oscillator circuit followed by a comparator", you've got a bit of a
haul.

Good luck
Chris

 

[Bob Masta]

Hi guys i am in the process of trying to figure out how and where to
start to build a Analog to digital converter for a project. I have
done some research and it seems that at the basic level its nothing
more that a pulse oscillator circuit followed by a comparator. The
specification i must stick with are :
1. max input freqeuncy 100khz
2. successive approx type with best guess centering
3. max bits are eight
4. max error of 1% at output

If anyone can direct me to some circuit diagrams or information, i
would appreicate it.

thanks
peter

Successive approximation types are built around a D/A
converter and comparator. You compare the input signal
to the output of the D/A. Toggle the MSB of the D/A and
if the D/A output is now too big (comparator switches) you
turn that bit back off. Continue for all bits.

You can build a dead-simple D/A for this from a simple
R-2R resistor ladder, driven by any decent CMOS
digital output. A buffered printer port on an old PC
works fine. Full discussion of this, and software to
run it, at
www.daqarta.com/lptx.htm

Best regards,


Bob Masta

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Signal Generator
Science with your sound card!

 

[Rich Grise]

This looks like another example of someone asking for help with their
homework assignment.

Well, you have to give him a point for disguising it well^H^H^H^Hbetter
than most. ;-)

Cheers!
Rich

 

[Rich Grise]

Hi, Peter. Actually, you're supposed to put a dab of quicksilver in
the loaf before you set it afloat. It stops in the newsgroup right
over the answer to the homework question. All ah see heer is a plain
loaf. ;-)

Not that you really need this, but you might want to look at Analog
Devices Appnote AN-289. No link -- as a bonus, you'll have to look it
up yourself.

If it "seems that at the basic level its nothing more that a pulse
oscillator circuit followed by a comparator", you've got a bit of a
haul.

64X LM339 + 8X 74HC148 + a buffer & some glue logic should do it. ;-)

Or maybe that should be 9X 74HC148 ;-)

Oh, wait! That's a flash converter - the teacher wants an(a) SAR. >:->

Cheers!
Rich