1 Topic by julien breval (edited by julien breval 2011-01-09 19:35:29)

  • Registered: 2007-11-05
  • Posts: 67

Topic: Making a power supply for my mobile case

Hello,

In my portable music case three devices use wall power supplies: RME Fireface 400, RME Quadmic and Marian ADCON. I would like to power these devices with a single, rackmounted power supply.

Here I have a 25€ industrial power supply that should be OK from its specifications:

* 12V output
* 3.5A
* 40W
* sockets: L (AC), N (AC), ground, -V, +V
* metal box with holes

http://www.ohmeron.be/content/index.php … mp;lang=EN


But I have never made a DIY PSU before so I am not sure about some things:

-> According to the manual, polarity is not important for the Quadmic but I don't know for the FF400
-> Is it necessary to connect the PSU ground to the RME boxes?
-> Can I really power 3 devices from the same -V and +V sockets?
-> I would like to add a single on/off switch; is it better to switch 220V or 12V?


Best regards
Julien

  • From: France
  • Registered: 2007-09-14
  • Posts: 113

Re: Making a power supply for my mobile case

[img]//img232.imageshack.us/i/ffucpowersupply.jpg/[/img]I guess the FF400 being powered as my FFUC :-)

-> you do have to respect polarity of the incoming 12Vdc power
-> not necessary
and I would personaly not do it as the unit casing has common grounding with digital signals  such like the WC & SPDIF, which increase the risk for damage in case of leakage at the AC industrial power supply
-> I do not see any foreseeable problem in powering three units from the supply assuming you switch them one at a time
-> 220V side  is better from my opinion, in order to avoid the  increase of the switch specification for sourcing high current load (to be likely around 5~6 amps DC)

Alternatively, I would recommend you to use a DC battery as shown, or even with more capacity in the range of 7Ah
with the big advantage of being independent of the local power outlet, and its consequent possible spikes and microcuts
(further more no risk for potential high frequency switching noise coming to the sensitive preamps with the industrial unit solution) 
But if AC is available, until recording being started you can leave the charger connected to maintain the battery full capacity, and the FFUC is proof against any rumble from this supply

http://img232.imageshack.us/img232/3421/ffucpowersupply.th.jpg

Uploaded with ImageShack.us

Whatever your choice, keep the original power supply back connector of RME and cut the cable somewhere to install some connectors of automotive type (as me) or similar to that, or the main switch you are thinking about
This way, you will not take any risk on using another connector plug from the nearest electronic store which may not mate properly and safely to the PCB

Je suis Français, si vous voulez continuer la discussion en mp ..

Pierre

HDSP9632, HDSP9652, ADI-8QS, FFUC, Quadmic II
  • Registered: 2007-11-05
  • Posts: 67

Re: Making a power supply for my mobile case

Thanks a lot for your answer Pierre smile

Schubertriad wrote:

-> not necessary
and I would personaly not do it as the unit casing has common grounding with digital signals  such like the WC & SPDIF, which increase the risk for damage in case of leakage at the AC industrial power supply

ok, so I will leave the ground unconnected, to start with

-> 220V side  is better from my opinion, in order to avoid the  increase of the switch specification for sourcing high current load (to be likely around 5~6 amps DC)

two different persons advised me to switch the 220V side, so I guess I will do it then

-> I do not see any foreseeable problem in powering three units from the supply assuming you switch them one at a time

how can you switch the devices one by one if you are switching the 220V side?
is there something wrong when switching all the devices of the case at the same time?

Alternatively, I would recommend you to use a DC battery as shown, (...)

it's not possible for me as I have a fourth device that requires 220V AC

Whatever your choice, keep the original power supply back connector of RME and cut the cable somewhere to install some connectors of automotive type (as me) or similar to that, or the main switch you are thinking about
This way, you will not take any risk on using another connector plug from the nearest electronic store which may not mate properly and safely to the PCB

good advice, I completely missed it and bought some (very cheap) connectors, so I will use the original ones instead!

Je suis Français, si vous voulez continuer la discussion en mp ..

En fait j'ai répondu en Anglais car j'imagine que davantage de gens peuvent comprendre, au cas où ça les intéresse (beaucoup de gens pestent contre les alimentations murales smile

Merci encore
Julien