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aout_lc_module [2016/08/04 23:44]
psykhaze [Introduction]
aout_lc_module [2016/08/04 23:46]
psykhaze [Introduction]
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 =====Introduction===== =====Introduction=====
  
-The idea behind the AOUT_LC module was to realize control outputs with parts that are easy to get in most countries. After a discussion with Karl Dalen about the difficulity to find DIY friendly DACs with a serial interface. He proposed these {{http://​www.midibox.org/​users/​kd/​KDdac.pdf|circuits}},​ and the discrete solution was selected because of the simplicity. ​+The idea behind the AOUT_LC module was to **realize control outputs with parts that are easy to get in most countries**. After a discussion with Karl Dalen about the difficulity to find DIY friendly DACs with a serial interface. He proposed these **{{http://​www.midibox.org/​users/​kd/​KDdac.pdf|circuits}}**, and the discrete solution was selected because of the simplicity. ​
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-In difference to the [[AOUT_Module|AOUT]] or [[AOUT_NG]],​ this project doesn'​t require a special (expensive and hard to get) DAC IC, instead resistors are formed to a discrete R-2R ladder network. Building such a circuit means a lot of soldering effort, but as the MBHP is indented as a Do-It-Yourself platform, and not as a commercial product, this argument is very weak. However, the resistor ladder could be replaced by a DAC with parallel interface (see Karl's schematics),​ this would still have the advantage, that the DACs are accessible via a serial chain (-> low number of uC pins are allocated), and that the software driver doesn'​t need to be adapted for a proprietary interface.+In difference to the **[[AOUT_Module|AOUT]]** or **[[AOUT_NG]]****this project doesn'​t require a special (expensive and hard to get) DAC IC**, instead ​**resistors are formed to a discrete R-2R ladder network**. Building such a circuit means a lot of soldering effort, but as the MBHP is indented as a Do-It-Yourself platform, and not as a commercial product, this argument is very weak. However, ​**the resistor ladder could be replaced by a DAC with parallel interface** //(see Karl's schematics)//, this would still have the advantage, that the DACs are accessible via a serial chain (-> low number of uC pins are allocated), and that the software driver doesn'​t need to be adapted for a proprietary interface.
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-Regarding the quality of the "​discrete DAC" outputs it should be mentioned, that it directly depends on the chosen resistors. The tolerance should be 1% or lower (Metalfilm) and stable over the typical temperature range. The results can be dramatically improved by selecting the best matching resistors: just buy a set of 100 pieces , measure the resistance and take the ones with the best matching values for the ladder circuit.+Regarding the quality of the "​discrete DAC" outputs it should be mentioned, that it **directly depends on the chosen resistors**. The tolerance should be **1% or lower (Metalfilm) and stable over the typical temperature range**. The results can be dramatically improved by selecting the best matching resistors: just buy a set of 100 pieces , measure the resistance and take the ones with the best matching values for the ladder circuit.
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aout_lc_module.txt ยท Last modified: 2016/08/04 23:46 by psykhaze