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Author Topic: Arduino controlled battery power for DAC  (Read 1886 times)
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I build a power supply based on a 7Ah Lead battery and used an Arduino microcontroller and two relays to switch between regular power supply and battery. The Arduino is programmed to detect music flowing through the Dac and than switches to battery power immediately. Between songs the Arduino waits 2 minutes before switching back to regular supply to save battery power. When the battery is almost drained while music is playing it also switches back. To compare the battery powered sound with regular powered sound I added a infrared eye to the setup so I can switch between battery and regular supply from my listening position.



In front the main power switch, a USB connector to program the Arduino and a LCD display that shows the battery voltage, the dacs' current usage and the psu-switch status (OFF, Music or Charging).



Inside is the 12V battery, a 12V psu, an Arduino powersupply, the Arduino, two relays and a battery charger.



Schematic with measurement of Current and Voltage


To my disappointment I don't hear any differences. So for me it was a lot of fun building but not the expected results.
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To my disappointment I don't hear any differences. So for me it was a lot of fun building but not the expected results.

  Actually that is a great indication of your personal integrity and honesty. So many in the audio world (the 'golden ears') have really drunk the cool aid on what they think can effect sound quality. An example, many  spend hundreds of dollars (or more) on 'designer' AC power cords for their audio amplifiers and will then swear they can hear a difference. Show them technical measurements showing no change in signal quality and they will just say you are just not measuring the right thing. One fundamental problem with the 'golden ears' group is that most have no firm understanding and education in electronics, so to them it must all be magic and therefore anything can have a positive or negative effect on their electronics equipment. And too many that do have a formal grounding in electronics are often on the supplier side of these 'golden ears' products with their unbelievable markups. It's an amazing commercial market and I'm so surprised some of the firms can get away with most of their claims. They actually sell capacitors the same as a firm would sell vintage collectible wine and of course many will swear they can hear a difference between brand X and band Y capacitor of the same values. It's all in the proper aging of the dielectric material I guess.  smiley-grin

  
« Last Edit: July 17, 2011, 04:46:57 pm by retrolefty » Logged

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Nice project and clean, elegant casing in the end. Gratz !
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Arduino sound Reseach - http://bit.ly/fullmaj [fr][en] | Homemade Free VST - http://zomg.zxq.net [en]

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on 'designer' AC power cords for their audio amplifiers

Are you serious?  Gold plated?  Cool logo?  Pinstripes so the electrons will travel faster?  That is just bat guano crazy.
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To my disappointment I don't hear any differences. So for me it was a lot of fun building but not the expected results.
What is the Mains-powered DC supply?
You may not be drawing enough current to really stress anything, thus the DC into DAC is quiet all the time.
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Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
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Are you serious?  Gold plated?  Cool logo?  Pinstripes so the electrons will travel faster?  That is just bat guano crazy.

I'm 100% serious. The world of the high-end golden ear audio marketing is just crazy with fraud and outrageous claims. They will sell preamp to amp interconnecting cables that have directional arrows for the 'correct' direction of use, this for a cable handling an AC audio signal, WTF? And don't even get me started on the custom $10,000+ single tube class A amplifiers outputting around 7 watts, based on a pre WWII 300A vacuum tube! They will however at the same time shun any op-amp (or other solid state device) used in the 'audio chain' as causing the sound to have a sand flavor imparted to it, (silicon = sand) and should always be avoided.

But it always seems to boil down to it being a free market, and anyone is free to spend their money as they see fit no matter how absurd and/or dishonest the product claims might be.

Check this site out for your audio and power cabling needs: http://www.highendpalace.com/AUDIO_CABLES.htm

Lefty
« Last Edit: July 18, 2011, 11:26:40 am by retrolefty » Logged

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See, now $10K is just getting carried away. For a mere $700 plus tubes, you can get a very nice stereo amplifier kit:
http://www.triodeelectronics.com/st70buildkit.html
« Last Edit: July 18, 2011, 11:08:04 am by CrossRoads » Logged

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http://diyaudioprojects.com/Tubes/tubes.htm

Like Arduino, but with tubes instead of microcontrollers! Oh, and a little higher voltage ...

"Do-It-Yourself (DIY) vacuum tube (valve) amplifier and tube preamplifier projects. Please be aware that most of these vacuum tube projects use potentially lethal voltages that can kill you so do not attempt them if you are not familiar with high voltage safety! A couple of the tube projects are low voltage and if you are new to tubes and high voltage safety you should start with these. For those experienced with high voltage electronics, the S-5 Electronics tube amplifier kits makes a good and inexpensive first tube amplifier project. "
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I am aware that there are audio tube equipment (both assembled and DIY/kits) avalible at prices that accurately represent the component costs plus reasonable profit for the supplier. However other then their curiosity value I believe the only legitimate application for tube amplifiers today is for guitar amplifiers where the distortion products are part of the sound that the artist is trying to create. There is no questions that tube amps will sound difference then solid state amps when both are forced into their non-linear regions.

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"the only legitimate application for tube amplifiers today is for guitar amplifiers"

Not true, music thru tube amps sounds very good too. They run much hotter doing it tho.  I have a Dynakit-70 (kit built vs factory built) that I got on e-bay from someone selling it in the Boston area (took several attempts to get one).  Sounds very nice at normal listening levels. Have not tried a distortion meter to see if it is impacting the sound in a purely analytical way.

I was thinking about changing the gain stage to use it as a guitar amp, but then I built a guitar amp with 2 pre-gain stages instead to get that nice tube sound.
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Not true, music thru tube amps sounds very good too.


That gets down to one of the core philosophical differences between 'golden ears' and people that understand electronics. One sage engineer once said the 'perfect' amplifier would be a "short piece of wire with gain". What he meant of course was the true purpose of pre-amps and amplifiers is to faithfully reproduce the signals from the source of the music, adding and taking away nothing that isn't in the original program material.

 So when one says they hear and prefer the sound of a tube amp over a solid state amp (with better specification by far) they are saying they like the modification the tube amp makes to the original sound. That's fine as it goes, everyone is entitled to their preferences, as long as you understand what is the cause of why you like it better, it's because the equipment is modifying the signals rather then just amplifying them. Certainly the original artist and recording engineer didn't feel the need to add that specific 'improvement' into the original program material.  

So I'll continue to wish my audio electronics to be as accurate as possible to the original program material, rather then to add it's particular flavor to the music I listen to. Tube amps do sound different (that tube sound!), but there are specific electronic reasons for that, it's not magic. Speakers and room acoustics are the biggest variables in accurate audio reproduction as there one leaves the world of pure electronics and into the less perfect world of the electromechanical and audio reflections.

But then again there is a reason most pre/amps come with tone controls also, so you can modify the sound.  smiley-grin  
« Last Edit: July 18, 2011, 06:41:10 pm by retrolefty » Logged

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