surfparadise
Posts: 102
Joined: Fri May 10, 2013 9:01 am

Multiple voltage with one power supply

Fri Feb 28, 2014 1:35 pm

Hi, I'm making a project with different devices (sensors, pumps etc) that need different voltage to works (mainly 5v/12v/24v). Actually I'm using a standard USB 5v power supply for the raspberry and an external power supply of 5v for the sensors (connected to the gpio pin with mosfet to not damage it). I'm using darlington array to connect the valves (24v), with an external power supply (24v).

Could I use a unique external power supply of 24V for everythings? ....with a step down regulator for each device.... I have calculated the ampere that I need, and its should be enough....

One more question. In my actual set up I have 2 power supply (USB and external 5v for supply sensors and MCP23s17)...all works like a charm.... I connected the MCP23s17 via mosfets N to the GPIO SPI, and I'm using the 3.3V power pin of my raspberry to connect it.
I have try to power the 3.3v line of the N mosfet providing the current (regulated to 3.3v) from the 5v external power supply, instead of using the 3.3v pin of raspberry....Doesn't works at all..... Could you explain me why?

Thank you.

klricks
Posts: 7211
Joined: Sat Jan 12, 2013 3:01 am
Location: Grants Pass, OR, USA
Contact: Website

Re: Multiple voltage with one power supply

Fri Feb 28, 2014 1:55 pm

There are many regulators available. Try to use a switching or 'buck' type regulator. Something like this:
https://www.dimensionengineering.com/products/de-swadj
Theses are available in fixed or adjustable and also 1A or 3A versions.

Make sure everything has a common ground to the RPi. Other than that post a schematic so we can see what you are doing.
Unless specified otherwise my response is based on the latest and fully updated RPiOS Buster w/ Desktop OS.

User avatar
richiepp
Posts: 140
Joined: Wed Dec 19, 2012 4:56 pm

Re: Multiple voltage with one power supply

Fri Feb 28, 2014 2:06 pm

I'm running a 12V power supply and converting some of it to 5V using one of these
http://www.eachbuyer.com/dc-dc-converte ... MgodRWEAqw

I've been using it for about 6 months and it's working great!

Good luck!
Rich

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