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led's general

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Thread replies: 25
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I have never played with leds before but I am very excited.

I bought 10 of them but I didn't bought drivers.

I am actually planning to salvage parts to build those but I want to light 2 of them right now.

they are 3w leds.

will they be ruined if I hook a 5v 1 amp cellphone charger to them?

also led generals.

are they truly the path to the future or just over hyped bullshit.

pic related 2 of my leds being illuminated by an led bulb
Why do I feel deja vu from this post...

Is this bait
>hook a 5v 1 amp cellphone charger
sure. go for it.
what do you mean?
LEDs VERY sensitive to current(low current no problem, high current = pop). Voltage need roughly based on color.
Find a datasheet for those LEDs, op. They'll tell you how much voltage/current they can handle. If they're 3W, you're going to need some way of stepping down the power from your 5W charger, or those LEDs will burn out within seconds
but if I put 2 in line aren't they supposed to be taking 6w together?

I just wanna see them glow I am anxious, I guess I better buy/build a proper driver for this
Buy some cheap resistors to lower the current some just to be safe, anon. You can but a pack from walmart or something online for less than 10 bucks. Then, just hook them up in series with the LEDs.
Yes, putting them in series would make them the equivalent of a 6W load, but remember that LED stands for Light Emitting DIODE. Without any resistance in your circuit, current will flow unrestricted, and still most likely blow your LEDs
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This is all you need http://www.ebay.co.uk/itm/LM2596-DC-DC-Buck-Converter-Constant-Current-Voltage-Adjustable-Module-/161224221533

But yes you do need to limit the current some how, LED's like that normally need constant current drive for best results. You might could get away with a large resistor but watch out for thermal run away, the hotter the LED gets the more current it draws for a given voltage. And this is very non linear so the current could suddenly shoot up.
Do you have a bench power supply with a current adjustment knob? If so set it to around 300mA and you're good to go.

The 5v supply will likely light them for a few seconds and then destroy them.
man those are beautiful do you think I might be able to hook the 10 of them on this?
Probably, what is the forward voltage of your LEDs?
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actual item description.

this are cheap Chinese so I don't know how honest they are


also wonder if those modules you show me could be substitutes for drivers as in running them constantly.

have you tried them?
do they get too hot?
10 might be pushing it for a single driver, you might need to use 2 or three.

Remember that in a buck converter like this the output voltage cannot be greater than the input voltage. Each LED needs some voltage to turn on called the forward voltage, and the power supply used to power this converter would need to be higher than the forward voltage of all of the LED's combined.

I'm guessing those LED's need about 4v each worse case scenario, so size the number of LED's based upon what kind of power supply you have available. And old 19v laptop charger could probably do about 4 LEDs per converter maybe 5 at a push.

There are boost converters available too but be aware that the output power cannot exceed the input power, so it will demand more current from your power supply.

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What kind of power supply do you have available? What is the maximum output voltage and current capability of it?

That converter could probably power about 8 of those LED's in series provided you have a 35v power supply.

If you just want to see light with your 5v 1 amp adapter then a 2.2ohm 2 watt resistor will do for short runs, just keep an eye on the heat and current runaway. This will light up one LED on its own only as 5v isn't enough for anymore.

Its best to always run them lower than the specified maximum, 650mA is around the most I would feel comfortable running these at for any extended periods of time.
thanks anon now that you put it in perspective it is actually a lot of power.

hope the brightness is worth it.

they are growth led for my winter indoors
I actually have a bunch of them.

I have one right in front of me that produces. 5v at 180 ma

that one might be safer.
>they are growth led for my winter indoors
Ah I see, cool. Well in that case a 30w mains powered LED driver is all you need if you don't want to be messing around with circuits.

This sort of thing http://www.ebay.co.uk/itm/Waterproof-10W-20W-30W-50W-Constant-Current-LED-Driver-Transformer-Power-Supply-/301157417197 should do (the 30w unit). As long as you choose a "constant current" type of driver it will be fine.

That 180mA is likely the maximum continuous current that the adapter can put out before it either shuts off or overheats if its an old style wallwart. I don't think it will provide any current limiting on its own but it can't hurt to try.
no you all put fear in my soul now.

I will buy a driver or build a proper one.

maybe try the 2.2 ohm resistor trick but I got to get out of another broken charger and is too late to be doing stuff right now.

I love this board there is always people ready to help.

probably the least salty board of all 4chan
I wish you good luck with your growing anon, for a permanent mess free solution that 30w constant current driver is probably your best option. They appear to ship world wide so it should come up in an ebay search in what ever country you happen to be in.
Wonderful. I might have to come over and smoke some of your harvest at some point.
5v will pop them, you need to limit voltage to 3.2-3.8

Resistors or down stepper will do the job.
Thread posts: 25
Thread images: 4

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