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Topic: Voltage Divider Array as a DAC... (Read 1 time) previous topic - next topic

cjdelphi

I watch Collin on youtube make his own 8bit DAC!!! Using resistors to divide the voltage (or just watch the video)

http://www.youtube.com/watch?v=b-vUg7h0lpE


-- 8bit shift register should do the job nicely, so what about 2 shift registers? 16bit DAC?? surely not? right?

cjdelphi

P.S if you want a giggle, turn on the CC (like teletext) "english automatic settings" option :D

Collin talks about Bit Burgers at some point lol (it's google's speech to text engine at fault lol)

robtillaart


Quote
so what about 2 shift registers? 16bit DAC?? surely not? right?

Works in just the same way

There exist complete R2R components like
- http://www.ece.uidaho.edu/ee/classes/ECE340/Notes/R2R.pdf -
or - http://www.newark.com/bourns/4310r-r2r-103lf/resistor-ladder-n-w-10-10kohm-2/dp/75K9799 -

16 bitters too
- http://www.semiconwell.com/r_net/swr2r16b.htm

Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

dhenry

That's what people meant when they said R2R.

It is practically impossible to build a 8-bit or higher R2R: the resistors required would be too expensive / impossible to get.


robtillaart

@dhenry
Is that also true for the components that have a build in R2R? I assume they are calibrated?
Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

Papa G

When you have the luxury of being able to laser trim the R2R network, as a semiconductor fab would have, they are very practical. You can buy 0.1% resistors which will get you a little past 8 bits for around $1.50 each. Home building a 16 bit R2R network would likely take hours of hand sorting with a VERY precise resistor bridge or lots of $$$.

CrossRoads

The English closed captioning is pretty funny - lots of errors there.

DACs with R2Rs can be laser trimmed at the factory for accurate level at the output:

http://www.analog.com/en/digital-to-analog-converters/audio-da-converters/ad1851/products/product.html

A part like that can be purchased for ~$12 at Digikey
http://www.digikey.com/product-detail/en/AD1851RZ/AD1851RZ-ND/936661

There's also some good information links there too, such as
http://dkc1.digikey.com/us/en/tod/ADI/DataConverterFundamentals/DataConverterFundamentals.html
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

CrossRoads

This one on DAC architecture is pretty interesting.
http://dkc1.digikey.com/us/en/tod/ADI/DACArchitectures/DACArchitectures.html
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

Papa G

DACs without voltage output, i.e. current output DACs, are essentially just precisely trimmed R2R networks, and can be had for less than you can build your own. Much more compact, too.  :)

CrossRoads

Can find all kinds of interesting things here:

http://www.digikey.com/PTM/PTMMaster.page?site=us&lang=en

Digi-Key's library of more than 1600 exclusive Product Training Modules (PTM) Onlineā€¦ On DemandĀ® product training modules is a collection of training tools created with you - the busy design engineer - in mind. They are provided with the cooperation of participating supplier partners. From this one source, you can learn about the latest products and technologies, download datasheets, check inventory, contact our technical staff, and place an order for same-day shipment.

These modules are available in audio and non-audio formats and listed by supplier in easy-to-find alphabetical order. Simply locate the module that interests you and click on your format of choice. We hope you find these tools useful, and with new modules added continuously, we invite you to stop back often to see what's new.

Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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