3x powersupply for rpi

ritsjie1971

TommyBoy wrotewhat is your LOADED voltage at v-min measured with a scope ?
to be able to generate 5.00 stable, with no ripple the min pulse must be over 6V
so your trafo deliver too Low voltage,
use a 9V AC trafo and shotkey diodes will give correct range, then add a pre-regulator adjusted to 6V
this way your transfer a perfect DC supply into your critical unit, and this way it can make perfect 5V and all the other voltages,

I connected a 15 Ohm 5 W resistor at the output. Without this load, i got about 8.7 VDC. That complies with 6 x √ 2. With the 15 Ohm load it's about 7.4 VDC. No ripple. I guess that's good enough for the LT1963's.
I use four of them. 5V for the DAC, 5V, 3V3 and 1V8 for the Pi. Each LT1963 will be supplied with the raw voltage coming from the rectifier. I'll have to dive in the circuitry of the DAC to bypass the onboard 3V3 stabilizer too, and adjust the 5V for the DAC at 3V3.

ritsjie1971

JohnC wroteI went down the external DAC route with clean power supply (DIY) with good results. This way, so long it's USB DAC Audio Class 2 compliant, I can have better control of what chip to be used and this method works with Rune very well:

A) The following post has a very simple method to separate the power supply using a Y-split USB cable. It works like a charm:

http://www.head-fi.org/t/634760/resonessence-labs-concero-discussion-review-thead/1320
Go to Post #1326 for the illustration. It works great with iFi iDSD Micro for DSD or DXD files.

B) Another option is to use a DAC that separates the power for you. I personally find the HiFiMeDIY Sabre USB DAC 2 (External PSU) sounds good and have good value for general uses.

C) Lastly, the linear power supply mod for HiFiBerry DAC+ Pro is pretty straight forward. https://support.hifiberry.com/hc/en-us/articles/205732441-DAC-Pro-external-power-supply

John

Interesting!

I have a M-Audio Audiophile USB laying around here.

It suprises me in a positive way how good it sounds. It has a seperate power supply and is detected by the software without any hassle.

ritsjie1971

I finished my power supply.

: 20170304_111607.jpg (126.6 KiB) Viewed 4781 times

It's very compact (6 cm x 3 cm) because I want to use the housing of the 7" display. I got a HifiBerry case in which the Pi and PiFi DAC are placed. This is mounted on the back of the housing for the display. So I can use the left space for the regulator board. I can install heatsinks when required.

My overal schematic:

: 20170222_164029-1.jpg (112.41 KiB) Viewed 4781 times

I do use the option to switch power via the regulators via the SHDWN line. Each regulator is fed via the unregulated supply coming from the rectifier. I use the trimpots to fine tune the output voltage.

vincenzomaletta

Hello,

first of all, compliments for your work and your detailed explanations.

I'd like to know why did you use adjustable version of the LDO, and not the fixed one for 3.3 and 1.8 V.

I also see that you put a small capacitor in parallel to each diode. I've never seen such a configuration; what's the scope of those capacitors ?

LBNL: using 4 filtering capacitors instead a single bigger one, has any benefit on the output ripple ?

Thank you for your answers.

Vincenzo

fboe

I'm really pleased to see that some people have tried my psu tweak, but what is your conclusion about the sound? - does it make a difference and if, in what way?

Cheers

Anders

DomieMic65

fboe wroteI'm really pleased to see that some people have tried my psu tweak, but what is your conclusion about the sound? - does it make a difference and if, in what way?

Cheers

Anders

yes this would be great knowledge for the people who haven't got the skills to build the 3xPS too!
I want to have a profesional build me a LPS but I do not know if it is worth it to oder a 3xPS and have him modify the rpi board too!
May be only to give power through the GPIO..

ritsjie1971

vincenzomaletta wroteHello,

first of all, compliments for your work and your detailed explanations.

I'd like to know why did you use adjustable version of the LDO, and not the fixed one for 3.3 and 1.8 V.

I also see that you put a small capacitor in parallel to each diode. I've never seen such a configuration; what's the scope of those capacitors ?

LBNL: using 4 filtering capacitors instead a single bigger one, has any benefit on the output ripple ?

Thank you for your answers.

Vincenzo

Sorry for my late reply, I'm quite busy at the moment.

Thank you for your compliments.

I use adjustable ones, because I couldn't get the fixed ones very easy. I've finetuned the voltages and everythins is stable as a rock now. The 1V8 and 3V3 get really hot (logical), the 5V for the Raspi too (also logical). They all got a nice heatsink now and temperature is acceptable now.

The parallel capacitors take care of any HF noise. I used shottky diodes, the capacitors are just to be sure. I've good experience with this design which I used before. Be sure to use ceramic capacitors.

Four filtering capacitors in parallel gives a better ESR result than a bigger single one.

Richard.

ritsjie1971

fboe wroteI'm really pleased to see that some people have tried my psu tweak, but what is your conclusion about the sound? - does it make a difference and if, in what way?

Cheers

Anders

I'm very happy with it! The biggest gain was when the DAC got it's own supply and the DC/DC converter was amputated, Also the seperate 1V8, 3V3 and 5V for the Raspi is highly recommended.
The lineair supply gives a lot more punch. Lows are more stable, highs are much more clear.

Of course the rest of your audio chain should be able to let you experience this.

ritsjie1971

DomieMic65 wrote
fboe wroteI'm really pleased to see that some people have tried my psu tweak, but what is your conclusion about the sound? - does it make a difference and if, in what way?

Cheers

Anders
yes this would be great knowledge for the people who haven't got the skills to build the 3xPS too!
I want to have a profesional build me a LPS but I do not know if it is worth it to oder a 3xPS and have him modify the rpi board too!
May be only to give power through the GPIO..

See my previous reply.

thanhvo31

Very nice modding gentlemen
Since I have many friends who eager to possess so call 3xPi while lazy or no skill of soldering.
I have plan to make a mod version so call Audiophile Pi version including:
A PSU supply clean 5V- 3V3- 1V8 - Ground via a male socket.
A mod pi with jumper, (SMPS not remove, just wire a "key" pin through a jumper) >> normal socket via 5V microUSB;
and "Audiophile" Female socket with 4 wires GPIO 2, PP8, PP9, GPIO 6)
A worst scenario: no jumper, just Female socket.

So is that possible?
Thank you for your input.

fboe

Hi

That will be a tricky mod, because you have to disable the onboard regulator to power it with 3 x eksternal power, and then enable it with several jumpers to power it with USB.

Cheers

Fboe

thanhvo31

Hi all
I intend to contact for customize Pi with low noise LT3045 on board. But minimum order size must be 1000.
Do you attend this group buy?

pelliott321

I'm in if the price is not too bad, do you have a quote yet

thanhvo31

pelliott321 wroteI'm in if the price is not too bad, do you have a quote yet

Nope. Just waiting.

dror

Hi,

According to topic opening, a small but probebly noticable tweak would be feeding a 5V via GPIO 2 and 6.
Can I use my regular standard rpi wall supply for this?

Thanks,
Dror

thanhvo31

I share My setup

Just change LT1084 by LT1963 x3 supply for 3xLT3045 to pi3x4wires

pistollero

thanhvo31 wroteI share My setup

Just change LT1084 by LT1963 x3 supply for 3xLT3045 to pi3x4wires

I how it sounds? Do you need to remove any regulator on pi or just solder the 4 wires?

pistollero

What are the 1963 config?
7.5v 5v 3.3v ?

dror

Nice share. thank you!
But again I'm asking if a regular standard rpi power supply could be used for the 2,6 GPIO pins tweak. I would try it myself if I wasn't afraid of damaging the rpi/DAC

Dror

fboe

dror wroteNice share. thank you!
But again I'm asking if a regular standard rpi power supply could be used for the 2,6 GPIO pins tweak. I would try it myself if I wasn't afraid of damaging the rpi/DAC

Dror

You can use the standard psu to pin 2 and 6 - but its a noisy switchmode, so I would recommend a linear psu. They can be found on ebay to a good price.

Cheers

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