Hi, i’m planning to make a volumio streamer and i would like to have some help on the realization of the psu.
Thinking to buy a Talema 70030k (i’ve seen this in a lot of implementation in the project section, plus is cheap), could you please tell me if is ok to use it and what i need in order to convert the 7v in 5v and use it for powering the raspberry and a pi hat dac?
Regards, Marco.
Should something like this works?
DC CC Max 9A 300W Step Down Buck Converter 5-40V To 1.2-35V Power Supply Module For Arduino XL4016
Please i need a little help 
Regards, Marco.
I would be inclined for a regulator series type LM317 or LM350, and a transformer of 9V + 9v and at least 50VA
Hi,
Transformer is far toooo low on power. You must have at least 30VA / transformer winding ; you must have 2 different 7…8 V windings if you want to separate RPi power supply from DAC . Also need :
All of this are only for RPi power supply . If you need separate power supply for DAC must double this.
If you need a schematic , just say .
yes please
Hi! Thanks for answering ! Are you sure that all that VA are needed?
I’ve seen lot of projects with lower transformer, for example this one:
Project of the user p1234321 on this forum/ Diy Volumio Projects section.
Atm i would be happy with only alimentation of the rasp
Regards, M.
Ok, This one has 7,5 VA per winding. If you use Raspberry Pi 3 this is not enough. I think he put both windings in parallel but this is not recommended for some reasons. In this case DAC don’t use too much power and if you use one of this a winding with 5VA is enough ( but I never see transformer with 2 windings at the same voltage and different power). Better to use 2 different transformers one with 20 … 30VA and one with 10VA, both on 7V
What’s wrong with parallel winding???
Also please note that under normal condition Raspberry Pi current consumption under 1A
(my Pi2B with Allo Piano Dac and TPLINK USB WIFI dongle using about 0.7A average, PI3 with Hifiberry DAC - even less)
There is no problem if the windings are correctly connected, complies with the connection conditions ( U & Z ) and come from a good manufacturer .
PS: don’t know why but my RPi3B with Kali Reclocker and PiFiBerry usually takes 1.4-1.5A . And, in audio electronics, I respect old Russian standards: whatever it takes make it double 
And my circuit:
DB1 & DB2 : rectifier bridge 50V / 5A and 50V/3A with 8x 10nF / 50V ceramic capacitors ( capapacitors are not realy need it but if you can, add them)
C1 & C5 : 2 x 15.000 uF / 16V capacitors ( Nichicon: UVY1C153MHD ) - C1 can be larger or better add one more in parallel
C2, C4, C6, C8 : 4 x 100nF / 50V capacitors ( ceramics)
C3 & C7: 2 x 220uF / 10V capacitor ( Nichicon UES1A221MPM ) or 22uF/10V tantalum or both
D1 &D2: 1N4003 … 1N4007
You can change first LT1085 with LT1084 fixed regulator for RPi power .
I plan to use a transformer of at least 50VA and 9 + 9V in my new project.
Can you give me an address where to buy it online?
I think 8x8V or 7x7V is enough . If you rise secondary voltage , much power will drop on LT1085 regulators make it hoter and you will need a bigger cooler . You can buy one from TME :
tme.eu/gb/details/tst50w_2x … /tst50002/ - 8x8V 50VA toroidal.
tme.eu/gb/details/6510k-p1s … rs/talema/ - 7x7V 50VA toroidal.
Hi everyone!
And what about something like this: https://www.audiophonics.fr/en/linear-regulated-psu/linear-power-supply-module-double-dc-lt1083-24v-5a-p-11793.html?
2 adjustable output from 2,5V to 24V DC at 5A(I’m not sure about that but I believe you have to divide it by 2).
So you can get for example:
Step Down converter is not good for audio applications.
How much money want you spend for this project?
You want to say the fact that it is adjustable?(really not electrician ) Why? It creates parasites?
I did not really think about that. I think 30€ is reasonnable for one of the most important part of the project. Perhaps 40/60€ for a PSU ready to connect with the 220v…
Hi,
This is not a step down but a powerful linear converter.
I can recommend it.
You even can get it for less than the half in China if you’re not in hurry.
https://www.ebay.de/itm/Assembled-LT1083-Adjustable-HIFI-Linear-Regulated-Power-Supply-Board-Dual-0-48V/253477392391?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
This one even comes with high quality Nichicon capacitors.
It has 2 totally independend regulators each of them is capable to do up to more then 5A - if your input voltage is not too high.
I’d recommend 2x8V AC to get enough heap for regulation, but not more because the heat is increasing with more input voltage like Apache already recommended this, too.
By the way it has 2 LT1083 regulators which are very similar to the LT1085 ones.
Just quick and dirty, but to get an impression on how this works:
8V - 3V = 5V ----- so if you feed 8V to your linear regulator, it has to burn down 3V and if you draw 5A out of it you get a power of 15W (3V x 5A) that has to be converted to heat.
In your case the 3,5A is a absolute peak value that is seldom reached - so you get a heat dissapation of 3Vx3,5A which is 10,5W at absolute max. but mostly lower. (~1A if you do not have connected much else to the RasPI) so ~ 3W at average
If you use a metal case with enough room the cooling of the device is far enough.
Best regards
Josef
Ok, thank you for the EBAY link and the precise explanations!
So the toroidal proposed by Apache
should do the deal.
Last question: What is the best solution to fix the transformer in a case? That must propagate much heat… It seems it’s delivered with a plate. So, just screwed on a piece of a proto card maybe?
Hi,
The transformer won’t even get “hand warm” with this load - no worries.
Most important step at this point is to avoid any kind of vibrations.
There are some fixing sets out to do do this - about up to 6€ about - use that or cut out some heat (warm) resistant gum and metal to build it yourself.
https://www.it-tronics.de/en/Toroidal-transformer-mounting-set-110mm-accessory-material-fixing.html
Josef
Ok, thank you very much!
For those who are looking for a 2x8v toroïdal, I just found this one: https://www.audiophonics.fr/fr/transformateurs-toriques/transformateur-torique-60va-2x8v-p-10640.html
More expensive than the one proposed by apache, but 60 VA and 3,9A. It allows to have a comfortable margin.