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3v boost up to 12v

Harald Kapp

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Why a boost controller?
You state your projects run on 12 V. To add 3 V LEDs you need to step down from 12 V to 3 V, not vice versa.

Apropos 3 V LEDs: usually LEDs are current controlled, not controlled by voltage. Unless you have special LEDs that have a built-in constant current controller, you'll need an external current controller or limiter, see e.g. our resource here.
 

kellys_eye

Jun 25, 2010
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All you require is a simple series resistor with each LED. Nothing more. See the link Harald posted above (post #2)
 

Harald Kapp

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You can use a simple series resistor alon, as suggested by @kellys_eye.

Or you can use one of the step-down modules you linked to in post #3 to step down to e.g. 5 V, then again use a series resistor to limit the current. This will be more energy efficient than a series resistor to 12 V, but more costly.

Your decision.

i want a 5v or 3v led
Which LEDs are you going to use? 5 V LED sounds like the LED has an integrated current source, then you wouldn't need a series resistor.
3 V LED sound more like a typical white LED with a pass voltage of 3 V at the rated current. But this does not mean you can connect the LED to a 3 V voltage source and expect the rated current to flow. You need to control (or limit) the current.
LEDs operate different from incandescent lamps which you can simply connect to the appropriate voltage source. Please read the resource I linked in post #2.
 

Harald Kapp

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O.K., these have an integrated controller, so you can attach them directly to a 3 V source without a series resistor.
 

bertus

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hello,

yes, that would likely work.
this is stated on the page:
5pcs Mini DC-DC 12-24V To 5V 3A Step Down Power Supply Module Voltage Buck Converter Adjustable 97.5% 1.8V 2.5V 3.3V 5V 9V 12V

the leds you have seen to work between 3 and 5 volts

as the leds only take 20 ma, you can activate a lot with one of those converters

bertus
 

Crafts4Me

Feb 10, 2022
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perfect so that means i can attach 3-5 of them to one step down and then to the rest of my 12v power adapter?
i will be brave and try it
thanks so much
 

Martaine2005

May 12, 2015
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LEDs can be driven as low as 1mA depending on the brightness you require.
That equates to 1000 LEDs per Amp (give or take).
 

Crafts4Me

Feb 10, 2022
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thanks so much
i made some orders
i will attmpt my project in May
i will keep everyone posted
i will be brave and attempt
 

Martaine2005

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Don’t forget the current limiting resistors.
Also, on a side note, you can wire them in series and forget about the buck converters.

Edit: if you use standard LEDs.
 

Crafts4Me

Feb 10, 2022
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hi
sorry
what does this mena?
i thought i didnt need additional resistors
 

bertus

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Hello,

The flame leds you are showing do not need a resistor.
There seem to be a current regulator on the board of about 20 mA.
On an 3 Amp down converter you can use upto 100 of you leds and still have some headroom.

Bertus
 

Crafts4Me

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ok
so back to my original question/statment
i ordered the flames and some step downs
i will wire about 3-4 together on the stepdown and then to my 12v adaptor power
i will try and see what happens
thanks
 
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