I have purchased a Raspberry Pi 3 B+. I have a question about powering this and other electronics in an outside, waterproof, ventilated junction box, similar to:
In addition to the Raspberry Pi, the box will contain a RTL2832U RTL-SDR dongle, a Low Noise Amplifier (LNA) for the 21 cm 1420MHz hydrogen line and two 5V cooling fans. The RTL-SDR is connected to a USB port on the Pi, and the LNA connected to the other end of the RTL-SDR.
The LNA requires 8v to 12 v at 150mA. Probably 9v would be OK to keep the temp down.
Ethernet 6A cable to the Pi will be sending raw data from the dish back to the computer in the house.
What would anyone recommend for powering this setup with a single power source, distribution and use of say, UBEC DC-DC converters?
Would this be possible to do as POE to Pi (e,.g. through the Pi POE hat/daughter board and then distribution to the other devices? For the LNA, I imagine a boost converter from Pi to 9v would be the way to go?
Looking for specific solutions please.
The PoE HAT will take 37–57V DC and output 5V/2.5A DC, so you would need to either split off the input voltage to a buck converter like this (only up to 42V input) to power the LNA, or like you said, boost the voltage from the Pi using something like this. Just make sure you don’t try to draw more than 5V/2.5A from the Pi with everything connected.
Also, in case you weren’t already aware, the Pi PoE HAT has no confirmed release date yet.
I’d be very interested in seeing this project once it’s done, it sounds really cool!
Thanks Josh, that info is very useful.
What would I need to inject power down the Cat 6 line? Would just plugging the Cat 6 into a computer RJ45 port be adequate to supply power to the Pi etc?
Any POE Injector would be fine. Something like that is outside our swimlane, but are common enough elsewhere (have a look around).
All the best with your projects!