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How much voltage is required to glow 9 led's.Even though i am using 15 volts they hardly glow.?

I am using 15 volts, still they don't light up .OR if there are other methods to supply voltage please help me (not the joule thief please).

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midhul6 years ago
You know that one led glows if you provide a supply or 1.5 volts(regular battery), then for 9 led's you can provide 13.5 volts to each! Maybe 15 volts is too much (usually is not!). Test your led's using a multimeter. You may have connected them wrong! Like + - + or _ - _ and shorted the circuit. connect them + - _ - + - _ ........ and so on! If it does not work try using resistors!
lemonie6 years ago
You have got all of them connected in the right way?

See here: http://led.linear1.org/led.wiz (LED series/parallel array wizard)
Add your details and it will advise how to wire them up.

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kshivamsh (author)  lemonie5 years ago
 After seeing your wizard i observed that i needed around 25 volts !!!!! which is too much could you suggest some other way out ?
You already gave the best answer on this, should I assume that didn't work?

Wizard: If you put in 15V, the voltage each requires (I don't know 3?), the current (I don't know 15?) and "9" it will produce a combination series/parallel diagram (tick wiring diagram or schematic box). You can do it if wired in the right way.

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Davetech5 years ago
Another way to identify the leads is to look at the led through a magnifying glass from the side. You will notice that each lead goes up to a little platform, but one of the platforms is larger than the other. The larger platform is the cathode and the smaller is the anode.
frollard6 years ago
As lemonie says - use that wizard to figure out how many to put in series - it depends on how much current each led needs, and how much voltage. Reds use 1.5-2 volts, green blue white purple use 3+ volts each.
purduecer6 years ago
How do you have them wired (series/parallel), and do they give you information about the turn on voltage somewhere in the spec sheet (if you have one, if not, what color are they)?