Low Noise Power supplies

 

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D asked 3 years ago

Please recommend a good linear power supply to run a rf project with 3 RPI, usb hub * 3 , including a Moitissier Nav Hat. I suppose need 5v * 20amps total max… or can have 2 smaller units.   thanks.D

1 Answers
Thomas Staff answered 3 years ago

Hello,
can you give more details on your project?
Do you want to use bus-powered USB Hubs (powered by Raspberry)?
Should the power supply be connected to mains?
Any space restrictions for the power supply?
 
Regards,
Thomas

D OC replied 3 years ago

THANKS FOR REPLY
this is a project for a boat. Lots of good DC, 12 volt supply, no AC powered systems connected.
I wish to use externally powered usb hubs from 12 volt supply.
On raspberrys with RF modules or sense HATS connected I wish to use a cleaner linear supply source.
So linear supply should be able to be powered by DC. and producing 5v*3amp * 3 rpi 45watt + usb hub 5v * 3amp * 3 hubs 45 watt, so I estimate maximum of 90watt clean supply required which will supply enough for the full scope of project. Can also use 2 * 50watt linear supplies.

Overall goal is rpi for ais, nmea server, nmea 2000 interface/conversion, NAS media server, web server, remote security monitoring.

thanks again.
D

Thomas Staff replied 3 years ago

In general, I would suggest using one single power supply for each RPI. Connecting devices together that require such high currents is not recommended. You might get voltage drops on all of the power lines if one device is drawing peak currents. This might result in noise, that could degrade your RF performance.
Be careful by selecting the USB hub, they are commonly intended to be used for PC purpose and might cause noise on the signal paths, which might affect the HAT.

Your power requirements are quite high. Unfortunately, I can’t suggest any power supply that fits your needs. I doubt you will even get a supply using linear voltage regulator technology. Due to space limitation, all those supplies use switching technology. If the supply is of high quality you won’t face any issues. However, be careful and use high-quality supplies only. They will have lower noise and might not affect the RF performance – but there is no guarantee. You might need to test different devices.
Try to keep power lines as short as possible and use ferrite beads and chokes.

Regards
Thomas

 

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