LED lighting question - probably an easy one but need some guidance! Thanks!

Thread Starter

ElectricAvenue

Joined Mar 18, 2018
7
Hi guys, I just need a bit of help as I am a little stuck, probably an easy one.

So I currently have seven circuits in series so far which will be connected up in parallel:

2 X 3528 30CM 15 SMD Waterproof LED Soft Light Bar 12V LED Car Strip Light (sides) (0.1 amps)

2 X 3528 30CM 15 SMD Waterproof LED Soft Light Bar 12V LED Car Strip Light (base) (0.1amps)

2 X 12V 16.4ft LED Strip Light Flexible 27S (27 leds) (0.23A) / 28P (28 leds) (0.23A) - (3014)

1 X (6 X colour changing LEDs(2V), + 6 Blue (3.2V) (31.2V) (0.25amps))

(Will probably adding another strip of 16-20 3528 leds in series which will be added to the other circuits in paralell)

I have a 12V 2AMP adaptor plug, just wondering if someone can talk me through what resistors to put on each circuit?

Also I am worried about the last circuit too, works out at 31.2V, but they are the specs of the ultrabright LED's, I am hoping I can run them at 12V just fine?

Thanks again to you all, just haven't done a project this big before so just need a bit of a boost.
 

ElectricSpidey

Joined Dec 2, 2017
1,869
Your "car" strips should already have the resistors installed in the strips.

The last one won't work. (they may light real dim...don't count on it, especially since they have built in circuits for the color change)
 
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wayneh

Joined Sep 9, 2010
17,153
I have a 12V 2AMP adaptor plug, just wondering if someone can talk me through what resistors to put on each circuit?
The first 6 items appear to all be intended to operate on a 12V supply. If that's true, none of them need any resistor. But don't take my word for it - the documentation should state the expected voltage range.
Also I am worried about the last circuit too, works out at 31.2V, but they are the specs of the ultrabright LED's, I am hoping I can run them at 12V just fine?
That's unlikely. At not much less than the forward voltage, LEDs won't conduct at all and thus won't light. They're not like incandescent bulbs that will glow dimly on a low voltage. You may need to arrange these into 3 strings all requiring less than 12V, and then use a resistor on each one to limit the current. Don't try to run them too close to their maximum specifications without good heat-sinking. They'll be plenty bright at much lower currents and that might be good enough for whatever you're doing with them.
 

shteii01

Joined Feb 19, 2010
4,644
The way you describe this one: 1 X (6 X colour changing LEDs(2V), + 6 Blue (3.2V) (31.2V) (0.25amps)), does not make sense to me, I can guess what you mean, but I am not going to bother.

You describe the first three as being bars and strips, this makes me think that they already have all the control circuitry, all you have to do is apply 12 volts to turn them On.
 

-live wire-

Joined Dec 22, 2017
922
Adding up the current draw for the 6 12V appliances, you should be fine (it being less than an amp). You should get yourself a boost converter for the last one. If it's intended to operate at 31V, you cannot use 12V! 31V * .25A is ~8W. So your boost converter would ideally draw 8W/12V = .666 amps. Realistically, it is not 100% efficient, close to 90% if it's a decent converter. So that is maybe .7 amps. That totals close to 2 amps. Maybe get a more powerful 3A+ adapter. Always get a higher-rated supply than you think you need. Just to be safe.
 

Thread Starter

ElectricAvenue

Joined Mar 18, 2018
7
Thank you to all your replies this is just what I need, I thought the 12V strips would have a resistor in, so they should be okay, so I dont need to do anything to restrict the 2Amp current on those?

The last, I will take your advice and split them up I think. Thanks for the info on the boost converter, that sounds interesting. So on that boost converter if I used a 3A adapter would that be better? Using your example, I would have .7amps and then just need a 12/0.025 = 480 Ohm resistor?

I just need 25mA on the LEDS max, and on the other strips Im afraid of blowing them or anything like that with the 2Amp current haha, I have blown a few leds thus far. Im open to suggestions on how to power this thing etc. thanks again for all your suggestions, I just bought the 12V 2Amp as I am currently building up the ship and building in circuits as I go and thought it would be okay.

Thanks to everyone by the way, I'm wiring up a cruise ship, deck by deck. I'm fine wiring up 4/5 LEDs no problem, but this project is massive haha.
 

ElectricSpidey

Joined Dec 2, 2017
1,869
so I dont need to do anything to restrict the 2Amp current on those?
Nope, they will only draw the current they need.

Since you will need a boost converter to power those color changing LEDs I would look for a separate supply for those since you will be pushing the 2 amp supply at that point, then you will have more power available for more LEDs if you need it.
 

MisterBill2

Joined Jan 23, 2018
9,467
Thank you to all your replies this is just what I need, I thought the 12V strips would have a resistor in, so they should be okay, so I dont need to do anything to restrict the 2Amp current on those?

The last, I will take your advice and split them up I think. Thanks for the info on the boost converter, that sounds interesting. So on that boost converter if I used a 3A adapter would that be better? Using your example, I would have .7amps and then just need a 12/0.025 = 480 Ohm resistor?

I just need 25mA on the LEDS max, and on the other strips Im afraid of blowing them or anything like that with the 2Amp current haha, I have blown a few leds thus far. Im open to suggestions on how to power this thing etc. thanks again for all your suggestions, I just bought the 12V 2Amp as I am currently building up the ship and building in circuits as I go and thought it would be okay.

Thanks to everyone by the way, I'm wiring up a cruise ship, deck by deck. I'm fine wiring up 4/5 LEDs no problem, but this project is massive haha.
While the current demand is not much, you should also add a fuse in series with the non-grounded power supply connection, and have the fuse fairly close to the power source. The fuse is to protect the wiring in case any mechanical damage causes a short circuit to ground. Especially on a marine application, fire prevention is important.
 

ElectricSpidey

Joined Dec 2, 2017
1,869
When you do the math for the resistors you need for any strips without them, don't forget to account for the voltage drop across the LEDs.

The formula is:
Supply voltage minus the voltage drop across all LEDs divided by the desired current.
 
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Thread Starter

ElectricAvenue

Joined Mar 18, 2018
7
While the current demand is not much, you should also add a fuse in series with the non-grounded power supply connection, and have the fuse fairly close to the power source. The fuse is to protect the wiring in case any mechanical damage causes a short circuit to ground. Especially on a marine application, fire prevention is important.
I will do this, sorry it is for a model ship. Is the fuse in the 3 pin wall plug enough?
 

Thread Starter

ElectricAvenue

Joined Mar 18, 2018
7
When you do the math for the resistors you need for any strips without them, don't forget to account for the voltage drop across the LEDs.
Sure, so this circuit here: 1 X (6 X colour changing LEDs(2V), + 6 Blue (3.2V) (31.2V) (0.25amps))

Using R = (Vs - V led) / I led

I could split into 6 x 2V leds, then need no resistor for this
The 2 X ( 3 x 3.2V leds - 88K Ohm resistor each

Okay I am getting somewhere now! :) I just plugged in the 12V power source and all the other circuits ran fine no problem!
 

Thread Starter

ElectricAvenue

Joined Mar 18, 2018
7
Oh definitely, its the least I can do! :) Hopefully you will all love the colour changing on board disco! Haha

Oh whilst you guys are around, do you know much about illumination wire? Does that need a driver or can I simply connect a power source?
 

Thread Starter

ElectricAvenue

Joined Mar 18, 2018
7
Sorry more questions, is there a sort of conduit that I can connect many wires into just two? I will connect them all to a home made switch box as well.
 

wayneh

Joined Sep 9, 2010
17,153
Oh whilst you guys are around, do you know much about illumination wire? Does that need a driver or can I simply connect a power source?
Yes, it needs a specialized power source. These provide something like 150V AC at 2kHz frequency and will be designed for a certain load range and a designated source voltage.
 

Thread Starter

ElectricAvenue

Joined Mar 18, 2018
7
Thanks for helping me out to you all, I am sure I will have further questions in the future. All of your answers have been great!

Will split that big series circuit into four,
The other circuits seems to run fine from the power source (12W 2Amp)

That will keep me busy for a bit, need to get some more strips in blue for lights out of the anchor ports and carry on up. I will post pics soon!

I have EL wire, I may encompass this as well I have a driver and a AA battery holder for these, be interesting that effect from a lighting perspective.

Thank you all - great forum!
 
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