LED Help

[CaptainK]

Hi All,
I picked up a few blue leds from here:

Blue LED'S

I was wondering if I need resistors or if I can just use one of those variable resistors so I could adjust the brightness myself?

Also is the long lead from the LED the positive or negitive side?

I will be power about 5 of these LED's with an old power adapter from an old desktop calculator. I forget...at the moment what the wattage is of it.

Thanks,
CaptK

 

[NateHanson]

If you wire them in series you might not need a resistor at all. That depends on the amperage of your power supply though.

 

[SHOmuchFUN]

A 15deg. viewing angle is going to produce a fairly narrow beam of light. May want to direct those to reflect in one of your lights reflectors to get a broader spread of light.

 

[CaptainK]

Here are the two power supplies and their outputs that I have:

6.2 VDC - 720mA
4.4 VDC 1.1mA

So what would I need for resistors and or a variable resistor?

Thanks,
CaptK

 

[BigCrowd42]

Long lead is positive and connect the resistor to this lead.Short is negative. Use a 90 ohm resistor if you cant get get a 90 use whatever is closest. This size is based on your 6.2v adapter.Do not overheat the led when soldering 3-5 seconds max with 30w iron

 

[BigCrowd42]

ps> 1 resistor per led