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In Reply to: RE: Optimizing power on the P24 pin. What way is worth the trouble? posted by Bertel on May 26, 2009 at 11:17:30
Robert,
My current setup uses a Power-One 12v / 1.7A supply for the P4 (fitted with several Black Gate 1000uF caps), a un-modified Pico 120 psu (currently changing the caps on another pico and putting together a linear 12v to replace the switcher) and a Power-One 5v 2A supply for the HDDs.
I am about to change it putting all the psu's in another case underneath the Antec case. So having read the various posts it seems to me that I should try your idea of switching the pico lines off and switching in three other linear psu's. So would I be correct in saying that for the P24 supply there would be effectively 4 psus, a 12v to power the picoPSU, another 12v, a 5V and a 3.3V psu? The first 12V (on the picoPSU) would stay connected with the 12V / 5V / 3.3V switching in and out.
Where do you have the switches? I assume that the picoPSU would not be plugged directly into the board but into a socket that feeds into the switch.
I have tried batteries on the P24 but it is the charging that made me change back to the Switcher/picoPSU; if changing over to batteries then I would like to leave the batteries in situ and when the pc is switched off they would connect to a charging circuit. For the moment I have too many other projects to pursue this idea - I am sure that a search of the web will give me what I need to know.
I also need to power my Juli@ from batteries - this one is high on my list as I have to break out the SPDIF and I2S signals to send directly to the DAC.
And of course then there is the time to listen to the music!!
Thanks for your information.
Alan
Follow Ups:
I am certainly impressed by your industriousness on the power supply saga. So I take it a 12 volt 2 amp supply is ok for p4? Also is the 12volt supply adjustable?
theob, the Power One linear supplies have a trimmer pot on the board - never tried using it though!
Alan,
your setup for P4 and the HDDs already sounds very good (maybe you might want to consider adding an additional cap like my 47uF Mundorf MLytic SI to the P4 line for supplying the current peaks most quickly plus a 1uF type for shifting all remaining AC fractions and interference into oblivion...? ;-) )
Regarding PSUs for P24 and position of the switches: Ok, I'm afraid I need to answer that again a bit too detailed... ;-)
Concept/layout:
- I haven't decided yet what I finally will use for powering up the system before switching over, the Antec or the picoPSU.
- You are right, when I use the picoPSU, I plug it into a P24 extension cable to get all the required lines "out of" the picoPSU.
- Once the system is completely powered up, I switch of all "special" lines (-12V, Power_Good, 5V_standby) with a 3-pole toggle switch right "before" the P24 connector.
- The capacitance detailed above is also sitting "before" the P24 connectors, the 1uF cap being the last in line and connecting all red / yellow lines for the 5V / 12V rail with its positive pole and a number of (in my case 4 for the 5V rail and 2 for 12V) black ones with its negative - you get the picture?
- 3.3V is different - I use a pack of 5 LiFePo batteries that supply exactly 3.3V for a long time and at an internal resistance of 2mOhm - no need for any regulators and caps here, direct is best possible :-) (I use an identical one to power Juli@ as per Alfred/sonics)
Switches:
- The switches for 5v and 12V are "before" the caps, i.e. between PSU and caps, thus their interference is irrelevant (I believe).
- Well, there is a switch between the battery pack for 3.3V and the P24 pins... Up to now it's still an ordinary toggle switch, but will upgrade to some "audiophile" switch (like for choosing source in a pre-amp, not decided yet which, internal resistance is the key)
- Another upgrade to come is getting rid of the P24 extension cable and soldering low resistance cables (thick ones with many wires for speed plus copper mesh for keeping HF interference out) directly onto the caps on one side and into gold-plated Molex P24 pins (got them thru Digikey) on the other. Well, you can't get too extreme, can you? ;-)
- All in all, this allows a very "pure" environment when everything is switched over or off - decent capacitance supplying clean power as quickly as possible to the various lines completely separated, fed by exactly regulated and also quite clean voltage from batteries. Probably sounds like overkill for most, but since current and voltage is basically everything and the starting point for any signal, it's my preferred point of interest, and in audiophile terms it absolutely pays for me :-)
Ah well, your thoughts about the number of linear PSUs to power pico: Well, you could get along with 3 linears for 3.3V, 5V and 12V, using the 12V one also to power the pico from the start and switch off the pico when you have switched everything over and the pico is idle then. But remember to size this 12V linear right - the 12V line only draws <200mA but needs to provide 4-6A while powering everything through the pico... I (of course) use a seperate battery... ;-) But surely that's not necessary.
Charging the batteries:
- I disconnect the 3.3V LiFePo packs and charge them elsewhere. not a hassle for me, once charged the last for days so that's a nonissue for me
- All the other batteries are in fact charged in situ (I like that) by manually connecting the required chargers. Not an elegant concept, I know, but I like to have the chargers completely out of the way for "serious" listening sessions, I don't have too much time for them unfortunately anyway (1-3hrs every second day on average) so again for me that's pretty manageable - and my "pure extremist" approach (no switch is the best switch) is supported :-)
BTW: Breaking out i2s from Juli@ to DAC - interesting! What DAC are you using? I'm going Buffalo32S at the moment... ;-)
Best,
Robert
Robert - I will digest your words over a glass of wine this evening - but as a quick response if you look for 'rebirth of the juli@' you will see all the details for the I2S breakout - as soon as I have done this (slightly differently as i will remove the Analogue board) I will take a photo and post.
I am also putting together the Buffalo 32s - hopefully I should have it in the system (using SPDIF) tonight or tomorrow. I am really looking forward to using this dac.
Alan
Robert,
I think I understand what you are doing and where, one question springs to mind - you say that you are using a 12v battery for the ATX24 which you switch to once the pc is up and running. Is this one SLA or is it several (is it even an SLA?) also (OK I cannot count) with the 3.3v you do not use any regulator as per sonics - what about the 12v?
Since I have a few spare Jensen / Black Gate / BHC capacitors I think I will first of all attack the setup as it is (i.e. no change of psu) and then look at the switching off / over of the supplies.
All of this will be after I have the Buffalo 32 settled in - all psus for that now up and running just a question of a few connections (and possibly putting it in a box).
Alan,not sure if I understand your question right - I probably was unclear on whereto I switch once the PC is up and running, right?
Let's assume for powering up the PC, I have the Antec Earthwatts connected to P24 (caps are in between on 5V and 12V lines). Well, "connected" isn't really precisely what it is - every line currently is going through a switch, two switches in total, one for the "special" lines (-12V, Power_Good and 5V_standby) and another one for 3.3V, 5V and 12V and the respective GND wires.
When powering up, all switches are so that every cable coming from the Antec has connection to its Pin on P24. When everything is up and running, I switch off the "special" lines. I then switch over the three main lines to their battery sources:
- For 3.3V I have a LiFePo battery pack (5 cells) directly connected, i.e. the wire from the switch that connects to the orange cables is connected to the positive pole, another wire that is now connected via the switch to two black lines goes to the negative pole of the pack. No regulators in between, no nothing - the pack is charged at exactly 3.3V and has a capacity of 2.3Ah so that they can keep exactly this voltage for a long time (due to the quite low current draw on this line of ~ 300mA) and give full advantage of their low internal resistance.
- For 12V I use a set of three preconfigured NiMH packs at 6V each (just so easy to handle and charge, of course you could use any 6V batteries that you prefer), so 18V in total, and feed them into a voltage regulator to bring them at exactly 12V. I know that most probably consider that as overkill, you usually use a 12V battery for a 12V circuit, don't you - but a 12v battery almost never is at exactly 12.00V, whereas I prefer to feed the digital circuits on the mainboard with an exact and always identical and reproducable voltage of 12.00V. (BTW I use the same setup for P4 to get to exactly 11.93V which has been reported to be the best sounding voltage by Bernd and Theo and others). Again, positive wire from switch to positive output of the regulator, negative wire to negative output.
- For 5V I currently use 4 8V VRLA Pb batteries (can't use the NiMH ones or other "weak" batteries because for 4-6A and regulated you need really strong ones, and these are). Each goes through one regulator (same as above) each to get to exatcly 5.00V. Again positive wires to positive pole etc.
Is this explanation halfways clear...? I promise to take a few pictures and post them - once I tidy up the still very experimental mess... ;-) That'll take a few weeks.
And you're right - what I described (except from the 3.3V line) all takes place "before" the capacitors, so they are really the most important part re quick and clean supply of decent power to the demanding circuits. By adding the spare caps you'll most likely will get substantial improvements already.
Cheers,
Robert
Edits: 05/28/09 05/28/09 05/28/09
Bertel,
I am trying to put together a diagrammatic representation of the various psu mods using batteries and switches that you have posted - I always find this helps me understand things. I will send you a copy before posting - to make sure I have understood.
I am trying to source the batteries and I thought I had a reasonably priced source for the LiFePo4 batts until I checked and one of them is dead! So after much searching through all the Radio Controlled Planes/Helicopters I think I found some decent ones - Graupner / Racing batteries at http://www.acemodel.co.uk/batteries/a123-lifes04-/1100mah-3-3v-single-cell/prod_199.html although they describe them as LiFeSo4!Are these OK? If not where do you get yours?
I can find many sources of 6V NiMh packs - but the only source for 8v VRLA batteries is China! Given that this is supplying the 5v work-horse line then the other styles of batteries do not have enough power. I suppose I could always use one of those Marine batteries - big enough to run a boat!
I have to say that searching for batteries has been quite an experience - I might just take up Radio-controlled Planes as a hobby - well it would get me out in the fresh air.
Any help/sources would be appreciated.
Alan
Alan,
Radio Controlled electric airplanes and helicopters is my other main hobby, so maybe I can help. Where are you located?
Greg in Mississippi
Greg,
I am in the UK in a town called Farnham (Surrey); I made my comment about Helicopters and Planes in jest - however I have now started looking at the various planes available. It seems that there is quite a selection from ones to use indoors to hi-performance outdoors types.
Near where I work is a very large playing field owned by the Army and there are quite often people flying planes - despite being close to one of the largest Army Barracks in the UK!
Regards
Alan
look at that handsome guy. that is a big plane!
Robert,
Thanks for the clarifications - I will spend some time now planning what to do - I have quite a lot of 6v SLA's sitting around not doing a lot, same as the capacitors; just need a few more regulators.
On the Buffalo side I have been wondering about how to put it into the PC without any interference - this would make the I2S leads as short as possible.
Photos would be great - but I would not like anyone to see my PC as it is - just a heap of wires - transformers open to the world - so when yours is all neat and tidy please publish.
Alan
how difficult was the buffalo32 to assemble? which ps did you get for it? nice.
theob,
The Buffalo 32 board itself comes built/tested all that is needed is to solder in the connectors - left out just in case you want to hard-wire it.
I bought three psu's so that I could drive each analogue channel separately - they come with all the components identified - there are documents on the website as to the board layout etc - very easy to build, the only thing that has to be done is to twiddle the 20-turn trimmers to get the voltages set as required.
All in all - very easy - hopefully it all works when I connect them tonight.
I am very excited for you--having ability to go I2S out to the Buffalo. Please let me know how it sounds. I am very interested in going this route too, just waiting for better time to finance it (2 trips to finance 1st).
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