Best Way To Supply Multiple DC Powered Items > 5v?

Hi Guys,

So I have multiple DC powered items I want my mega 2560 to control. Here's a few of the things I want to control, and their power requirements exceed the capabilities of the mega:

*12v 80mm LED Computer Fan *12v 5m LED Light Strip *6-8v Robot Motors x 2 *110v relays for 2 leads (not sure of the voltage to run the breakout board for this?)

What do you guys recommend to supply the necessary power for something like that? I assume we'd probably use a 110 connection and then step it down to some DC connections. Beyond that, it's a little over my head. TIA

What do you want to do with these components? Do you want to keep them constantly powered? Turn them on and off? Vary power supply? My initial suggestion would be to use a separate power supply and relays or transistors to allow the Arduino to control the power supply.

I hope helped :)

You need to know how much current each device takes. The relay is probbly not 110V that is just the rating of the relay contacts. You need to know the coil current and voltage. You add up all the currents together multiply by 1.4 and get the closest mains adaptor that will provide that current at 12V. The 1.4 is just to give a bit of margin on the power supply ratings.

Then you need to switch the power from the Arduino using a transistor or FET to amplify the current switching capability.

Grumpy_Mike: You need to know how much current each device takes. The relay is probbly not 110V that is just the rating of the relay contacts. You need to know the coil current and voltage. capability.

Good points. It would be helpful to know what you are trying to accomplish and have any circuit diagrams etc. you have made. Your relay can probably be run on the 5v from your Arduino. A wall adapter can supply you 12v into a breadboard if you are prototyping or into your final project (unless it needs to be cordless).

Transistors have always been a pit of a black art for me. What, in elementary/noob terms, is the purpose of a transistor? In simplest terms is it basically just a switch? I was always confused when they said it is used to ‘amplify’ the electronic signal…as if it was storing power up, and then letting a surge of power go through? It looks to me like it’s just a switch…you send a small current to the transistor to allow current to flow through it? I don’t know…maybe I’m totally wrong :frowning:

It looks to me like it's just a switch...you send a small current to the transistor to allow current to flow through it?

Yep that is it. That is also what an amplifier is. Small input large output.

So a transistor is basically a one setting amplifier...ie a switch lol. Quick question then, what's the point of capacitors and how do they work?

So here's my current setup. I have the mega 2560, and a 4 relay breakout board coupled with the bread board all mounted on a piece of acrylic.

Here's the image: |500x373image by Jeff Brown, on Flickr

Based on what I understand of my relays, each block can handle 10 amps of 120v power or 10am of 28v DC power. So let's say I want a 12v fan to switch on/off using one of the relays, and a 12v LED light strip to turn on and off. I also have 2 workshop lamps that I want to turn on and off via AC power. So what would you guys use to basically run all of that from one electrical bus?

Have another question. Would something like this single phase transformer work for taking the AC power down to specific DC levels?

http://www.ebay.com/itm/Voltage-Transformer-Active-Single-Phase-Voltage-Sensor-Module-for-Arduino-Mega-/351445847630?pt=LH_DefaultDomain_0&hash=item51d3ce0e4e

Whatever that device is, it is quite certainly not what you need in this circumstance.

It appears to be an "active rectifier" used to precisely measure an AC voltage.

jdlev: So a transistor is basically a one setting amplifier...ie a switch lol. Quick question then, what's the point of capacitors and how do they work?

No it is not one setting, it depends on how you wire it up. It is only a switch when you set it to give an output that is very much larger than the power supply feeding it can supply.

Capacitors simply store charge. However there are many uses, far too many for a simple answer.