Power supply question

Projects General Guidance
1

Hi
My project is 'working' but I'm still wanting to add/change/refine elements
The project is, using an Arduino to change the power source between solar panels and mains to a 6v water pump - that works.
I'm now looking at using one power source for both the Arduino and the (switched) mains to the pump
The Arduino needs 9v and the pump 6v
I assume I can use a 9v mains transformer and split the output, one to the Arduino 9v and the other to a Step Down Power Module (6v)

I need someone to tell me that's ok - or what needs changing - and hopefully point me at a suitably rated transformer

I have a 9v 0.6a plugin power supply - but have no idea if that will run both ?
I have a LM2596 adjustable Step Down Power Module

All help as always gratefully received

2

Yes this could work but are you sure 0.6A is enough current to power both arduino and your pump ? I really doubt it.

By the way, if you use step down module like this one:
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Their output is limited to 2A (up to 3A if you add a heatsink on the LM2596) but this should be more than enough for your pump.

The question is: how much current is required by your pump? Any marking about current or power?

3

I'm with guix I don't think you have enough current there. Why not use a large 6volt and step down to 5v for the arduino using the 5v pin instead of the vin pin?

4

Hi
I was fairly certain the power supply i have (6v 0.6a) wouldn't be good enough

The pump is
6V DC brushless pump
Mains plug: 6V 300 mA

So i need a power supply sufficient to power both devices (Arduino & pump) a higher rated 9v transformer or a higher than 9v with two separate stepped down units. Dont know which is the way to go with this.

drksam
your confused me, the Arduino needs a 9v power source doesn't it

5

Only if you use the on board regulator. I unduly use an external regulator as most of my uno projects are moved to atmega328 chips for the final version. The onboard regulator is fine for most but it is a touch small. Anyway you can put 5v to the 5v pin and it will work great be careful that you actually have 5v because that pin skips the regulator and higher voltages can damage things.

6

The Arduino require between 7-12V if you use the plug, but you can power it with 5V if you use the Vin 5V pin (which I don't recommend).

I use a 12V 5A power supply ( KY-60W-12-L, 7€ on ebay), on which I have some step downs to output different voltages (7.7V for the Arduino so the onboard voltage regulator is cold).

It all depend what you really need. If you may need to power 12V devices, then choose a 12V power supply.

If I understand, your pump require 300mA. I recommend at least 500mA for the Arduino. So it's 0.8A. Add a good safety margin, so buy a power supply that can deliver at least 1A :wink: