Can I use those power supplies for my project?

Projects General Guidance
1

Hello :slight_smile:

My project will need some voltages to power different things:

  • 230VAC for devices connected to relays (directly from a wall plug so no problem to get this voltage)
  • 12VDC for the relay board
  • 7.5VDC to 9VDC for the Arduino Mega
  • 5VDC for sensors
  • And maybe 3.3VDC for some other sensors.

At first I wanted to use a small ATX power supply, but I think this isn't a good idea because some work is needed in order to get the different voltages, and I'm not really electrician :zipper_mouth_face:

Then I found these things on eBay:

First, for 12VDC:

710×710 71.4 KB

Power Supply for LED Strip light Lights 12V 5A 60W 200-240V

Input Voltage:200-240V ± 5%
Input Frequency : 47/63Hz
Input Current: 0.5Arms max At any input voltage and rated, DC output rated load.
Inrush Current: 30Amps Max. Cold start at 240Vac input, with rated load and 25?ambient.
Ac Leakage Current: 0.25mA Max At 240Vac input.
Power Output Voltage: DC 12.0V
Short Circuit Protection: The power supply will be auto recovered when short circuit faults remove.
The power supply will be auto recovered when over current faults remove.
The power supply will not be auto recovered when faults remove.

Then, for other voltages:

LM2596 DC-DC adjustable power step-down module

Input voltage:4.5-40V
Output voltage:1.5-35V(Adjustable)
Output current:Rated current is 2A,maximum 3A(Additional heatsink is required)
Conversion efficiency: Up to 92% (output voltage higher, the higher the efficiency)
Switching Frequency: 150KHz
Rectifier: Non-Synchronous Rectification
Module Properties: Non-isolated step-down module (buck)
Short circuit protection: current limiting, since the recovery
Operating temperature: Industrial grade (-40 to +85 ) (output power 10W or less)
Full load temperature rise: 40
Load regulation: ± 0.5%
Voltage regulation: ± 2.5%
Dynamic response speed: 5% 200uS

I will chain some of these to get the different voltages:

12VDC ----------> to relay board
      - LM2596 -> 9 VDC ----------> to Arduino
                        - LM2596 -> 5VDC ----------> to sensors
                                         - LM2596 -> 3.3VDC ----------> to other sensors

So my question is, do you think this will work? Advices and warnings will be appreciated. I want to make sure I'm on the right path for powering my project :wink:

Thanks in advance 8)

2

no clue, what currents do you need, is that more or less than the supplies listed above?

3

Probably much less... I think!

The relay board: less than 500mA when all of the 16 relays are activated (which will never happen),
One or two 12V PC fans, which require 700mA each.
The Arduino Mega (and touchscreen): No idea yet, but I doubt it's more than 500mA
The few sensors: No idea yet, but again, I doubt it's more than 500mA

I don't need to power powerful motors or things like that directly from those power supplies, the heavy loads will be connected to the 230VAC through the relays.

I can't tell exactly now because I (still) haven't received any of my things yet, but I think I'm far from 2A that those adjustable modules will provide safely, and overall far from the 5A of the 12V power supply...I hope I'm right.

4

So my question is, do you think this will work? Advices and warnings will be appreciated. I want to make sure I'm on the right path for powering my project

Thanks in advance

That appears to be a very viable power plan to me. I've used one of those Asian adjustable switching regulators and it seemed to work just fine.

Lefty

5

So I buyed that 12v power supply and 5 of those adjustables modules for less than $18 shipping included.

Thank you Lefty, once again :slight_smile:

6

retrolefty:

So my question is, do you think this will work? Advices and warnings will be appreciated. I want to make sure I'm on the right path for powering my project

Thanks in advance

That appears to be a very viable power plan to me. I've used one of those Asian adjustable switching regulators and it seemed to work just fine.

I've bought a few of those as well, had no problems so far. I don't run them at full load though...

The rest of it seems complete overkill. The Arduino Mega will work with 12V and has built-in regulators for 5V and 3.3V.

If the current requirements are too high for the Arduino's on-board regulators then I'd use external voltage regulators for the 5V and 3.3V supplies. The 9V supply isn't needed, Arduinos are happy with 5V supplies connected to their "Vin" pin.

7

If the current requirements are too high for the Arduino's on-board regulators then I'd use external voltage regulators for the 5V and 3.3V supplies. The 9V supply isn't needed, Arduinos are happy with 5V supplies connected to their "Vin" pin.

No they are not happy powered that way. Vin voltage requirement is 7.5 to 12vdc.

8

Yes fungus I have read somewhere that what you said is no longer true in the recent versions of arduinos because of changes in the power circuit (can't find the post, but it was from a arduino team member).

I like to take care of my things, Arduino Mega require at least 7.5V, so be it, I will feed it with 8V so it stay cool :slight_smile:

I agree it may be a little "overkill" to not use the 5V and 3.3V from arduino, but it is more convenient for my project.

Thank you anyway!

Oh and today I received my Arduino and touchscreen! Let the fun begins!