henryhunt
Posts: 17
Joined: Sat Aug 27, 2016 11:31 am

Looking for a converter for 230V > 12V and 12V > 5V

Mon Jul 30, 2018 1:34 pm

I'm building a weather station that consists of a raspberry pi (with connected sensors) and an additional sensor powered from its own 12V supply. Currently (in an unfinished state) the setup I have is a simple mains-powered (230V) power strip in the enclosure, with the respective 12V and 5V transformer blocks for the two devices plugged into it. I now need to simplify this so I have a single outer "entry point" for the electricity at 12V, as opposed to the current 2 "entry points" (the two transformers) at 230V.

I'm looking for a converter to convert first from mains 230V down to 12V, which will be used to power the 12V sensor, and then another converter that will also be connected to the 12V converter output, to convert down to 5V which will be used to power the raspberry pi. The current 12V transformer block I'm using is 12V at 500ma, 6VA and the current 5V transformer block I'm using is the official raspberry pi one (5.1V at 2.5A). I assume that means I need a 12V converter rated for 3A and a 5V one rated for 2.5A.

These need to be "stripped down" converters with terminal block connections, rather than consumer-oriented power supplies with big, solid, enclosed builds, long wires and a mains plug attached (which is what I am currently using).

Do you have any ideas on what the best two converters for this would be? I've been looking around for some time but haven't got very far. Thanks.

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Mortimer
Posts: 885
Joined: Sun Jun 10, 2012 3:57 pm

Re: Looking for a converter for 230V > 12V and 12V > 5V

Mon Jul 30, 2018 2:09 pm

You mean something like this for mains to 12V?:
Image

For 12Vdc to 5.1Vdc, I think the consensus would be to look for a 12V-to-5V UBEC (Universal Battery Eliminator Circuit):
Image
https://www.modmypi.com/power-1137/hobb ... -converter


Image
https://www.adafruit.com/product/1385

hippy
Posts: 3575
Joined: Fri Sep 09, 2011 10:34 pm
Location: UK

Re: Looking for a converter for 230V > 12V and 12V > 5V

Mon Jul 30, 2018 2:59 pm

You can find laptop-style power bricks which take in 230V and supply both 12V and 5V at substantial currents with a common 0V. You can usually fairly easily modify those to deliver both 12V and 5V to an external enclosure using three core cable.

henryhunt
Posts: 17
Joined: Sat Aug 27, 2016 11:31 am

Re: Looking for a converter for 230V > 12V and 12V > 5V

Tue Jul 31, 2018 10:49 pm

That's exactly what I was looking for, thanks!

mosespi
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Re: Looking for a converter for 230V > 12V and 12V > 5V

Wed Aug 01, 2018 5:59 am

Another option would be to use a 19v laptop power adapter. Plug it in were convenient AC is available, then you can run a single pair of low voltage wire (outdoors too) to your weather station. Buck convert the 19v down to 12v, 5v or whatever else you need. Laptop adapters are fairly cheap and plentiful and the 19v will provide good overhead for voltage drop in even longish cables.

Regards,
-Moses
Power problems? MoPower UPS for the Pi
http://www.allspectrum.com/mopower/

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