Instructables

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).

midhul5 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!
lemonie5 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.
frollard5 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.
purduecer5 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)?