An (almost) linear power supply for my music PC

[thatguy]

After replacing the hard drive with a SSD and removing the optical drive and all the case fans, the SMPS fan became the noisiest part in the PC. When I started looking for a SMPS without a fan, I thought maybe I could put a linear power supply instead. Not only will it have no acoustic noise, it would solve the electric noise problem too.

It was while researching linear power supplies that I ran into picoPSU. A really tiny PSU that runs off a 12 volt power supply. Even though it is switched, the +12 volt bus carries the voltage that we feed into it. It was a quick way to get rid of the SMPS fan and the bulky SMPS itself.

The pictures below show the makeshift system I managed to get running today. The power is coming from a 3 channel lab power supply. Eventually, I intend to put a transformer/rectifier based power supply inside the case. Will update this thread as the build progresses.

The mandatory pics:






Since I intend to move to a USB DAC, I have temporarily abandoned my plans to build a fully linear ATX power supply. However, if sufficient number of folks (hopefully some from Bangalore ) are interested, we could start a community project. Would love to participate.

 

[captrajesh]

Does this mean going off the grid? (I mean going off the mains on to Battery power supply?)

 

[thatguy]

Does this mean going off the grid? (I mean going off the mains on to Battery power supply?)

I did explore the possibility, since the PSU only needs 12 volts (and about 1.6 Amps of current). However, I am not sure how well the battery can maintain its output voltage as it discharges. You really want to stay within the ATX spec (5%).

Right now, I am using a regulated lab power supply.

 

[captrajesh]

Would be interesting to see if this can be used to supply power to an amplifier.

 

[santhosh]

Way to go thatguy!!

I'd be interested in joining the group project and also try to get my music PC running on battery power like captain suggested.

 

[captrajesh]

I did explore the possibility, since the PSU only needs 12 volts (and about 1.6 Amps of current). However, I am not sure how well the battery can maintain its output voltage as it discharges. You really want to stay within the ATX spec (5%).

Right now, I am using a regulated lab power supply.

I think that is what the circuitry inside a UPS does. The only difference here is, we don't need the 12 volt DC converted to AC needn't be stepped up to 220 volts that needs to be fed to had it been a stock SMPS.

I'd be interested in joining the group project and also try to get my music PC running on battery power like captain suggested.

Santhosh, sorry if I confused you, I hope you have got what I meant.

 

[santhosh]

Santhosh, sorry if I confused you, I hope you have got what I meant.

Yes captain, the PICO accepts 12V DC input via a power brick. I think you are suggesting that the 12V input be from a battery instead. Correct?

We need to charge the battery somehow, but we have several options - solar, trickle-charging etc

 

[doors666]

You can also think about taking the smps out of the cpu box and making it external. you might need to 'extend' the connectors for that. since you are going to be using a usb dac, it wont need that much of a clean system as a normal sound card would.

 

[captrajesh]

Yes captain, the PICO accepts 12V DC input via a power brick. I think you are suggesting that the 12V input be from a battery instead. Correct?

We need to charge the battery somehow, but we have several options - solar, trickle-charging etc

Can't put it better:thumbsup:

 

[thatguy]

I think that is what the circuitry inside a UPS does. The only difference here is, we don't need the 12 volt DC converted to AC needn't be stepped up to 220 volts that needs to be fed to had it been a stock SMPS.

Capt, UPSs are almost invariably switched power supplies. Efficiency is a major concern in UPS and linear power supply will have a hard time achieving the kind of efficiency that a switch one does.

A lab power supply, like the one I am using, is optimized for accuracy. What I have done is to make at least one of the ATX buses (+12v) super clean.

We could feed off a battery and then use linear regulators to generate appropriate voltages.

EDIT: Looks like I misread your post. You probably wanted to connect the battery directly to the picoPSU. I did explore that option but gave it up after reading the specs of few lead-acid batteries. Apparently, the output of a battery varies from 11.x to 13.x volts depending on the charge. That kind of output should work for an amp or a preamp, but I am not sure how the MOBO will behave.

 

[thatguy]

Way to go thatguy!!

I'd be interested in joining the group project and also try to get my music PC running on battery power like captain suggested.

Santhosh, before going all the way (which will take time), I would suggest you try out the picoPSU option. I hate getting into discussions about sound improvements, but I have a feeling it did sound better

We can either carry my equipment (the power supply+picoPSU) to your place or you can bring your PC to mine.

 

[thatguy]

You can also think about taking the smps out of the cpu box and making it external. you might need to 'extend' the connectors for that. since you are going to be using a usb dac, it wont need that much of a clean system as a normal sound card would.

I agree. The folks who make the pico PSU even sell power bricks for about 20-30 dollars. I just want to do it to practice my electronics skills

 

[captrajesh]

Looks like I misread your post. You probably wanted to connect the battery directly to the picoPSU. I did explore that option but gave it up after reading the specs of few lead-acid batteries. Apparently, the output of a battery varies from 11.x to 13.x volts depending on the charge. That kind of output should work for an amp or a preamp, but I am not sure how the MOBO will behave.

Thatguy, I'm not as technically knowledgeable as you are.

Though I meant drawing power directly from the battery, I was also envisaging the scenario where the battery in question would keep getting charged in the usual way; could be through SMPS or could be via step down trafo. Regarding the technicalities and feasibility, I have no clue.

 

[anuragn]

Since I intend to move to a USB DAC, I have temporarily abandoned my plans to build a fully linear ATX power supply. However, if sufficient number of folks (hopefully some from Bangalore ) are interested, we could start a community project. Would love to participate.

Cannot resist saying: A nice power supply you have!

 

[josephjohnt]

It was while researching linear power supplies that I ran into picoPSU. A really tiny PSU that runs off a 12 volt power supply. Even though it is switched, the +12 volt bus carries the voltage that we feed into it.

I was also searching for making my desktop to run on batteries. I came across pico psu last month, but i have a graphics card which needs more power.

EDIT: Looks like I misread your post. You probably wanted to connect the battery directly to the picoPSU. I did explore that option but gave it up after reading the specs of few lead-acid batteries. Apparently, the output of a battery varies from 11.x to 13.x volts depending on the charge. That kind of output should work for an amp or a preamp, but I am not sure how the MOBO will behave.

They have models which accept a wide input voltage like this PicoPSU-80-WI-32V power supply

Dinesh, please count me in for your experiments. I need a PSU which can give more power. BTW i am also interested to build DC-DC Power supply regulators which can feed all low power devices like router, modem, external drives etc from the battery.

 

[kaushik]

joining matchsticks to replace rocket fuel?
linear psu:fine, what about mobo , it is not designed for audio.
picture this : a bulk battery+charger + bulk pc box running in a room there ASus like card decoding audio..difference is say 5%

will it not be good to mod a small device made for audio like SBT,use small batteries keeping things simple?

for desperate modder :best is to take Car pc with Good S.card... compact and ready for battery.
http://www.diymobileaudio.com/forum/car-audio-classifieds/71843-complete-car-pc-audiophile.html

 

[santhosh]

Hi Kaushik,
There are plenty of mods available for Squeeze Box. But this is different.

I was a big fan of SB, but have now moved to a music PC (AMD Fusion + ESI Juli@ Soundcard + Foobar) for the SQ and flexibility it offers me. I do not know much about electronics and have always wanted to get a Linear PS since I read it would be better. But cost of a Linear PS is quite high. Infact, I even hunted for very old PCs as I read that they had Linear PS. Dinesh has found a inexpensive way to do this and if he successfully replaces the SMPS (which is the major source of RF/EMI inside a PC) with a cleaner linear PS, I will follow suit .

 

[borg]

Thatguy, I'm not as technically knowledgeable as you are.

Though I meant drawing power directly from the battery, I was also envisaging the scenario where the battery in question would keep getting charged in the usual way; could be through SMPS or could be via step down trafo. Regarding the technicalities and feasibility, I have no clue.

captain

just get a battery charger powerful enough to float charge the battery and feed the smps for mobo and you are all set

 

[captrajesh]

@Borg, that is great news. I'll surely consider powering my Music PC if and when I make one.

BTW, nice to see you back. Are you still in China?

 

[cmsajith]

I am also interested in this project and my plan is to use solar panels to charge the battery so that the pc can run 24x7.