A few questions regarding AC/DC and what size resistor for multiple LED's

[peteski]

Since you are using 1k's and it's working, problem solved! 
But I am really curious about what value those other resistors are.  Can you measure one with an ohmmeter?

Yes, I would be curious too, but I think you hit it - they are 300 ohm 1%. That makes the most sense.

I'm also curious if the seller of the LEDs specified what value resistors they included with them. 300 ohm would be a good value when using a 5V power supply.

[dangerboy81]

I just noticed the resistors have printing on their folder. 3.5-5Vdc

[mmagliaro]

Well, there ya go. We've all been assuming the whole world thinks about powering LEDs with a 12v supply, so bad on us.  There's nothing wrong with the resistors, nor would they get hot if you ran 4 LEDs on one of those resistors off a 5v transformer output.  Ironically, they might not even light up.

[peteski]

Yes, the mystery's explained.  No, four white LEDs and resistor all in series would not light up from 5V, but Leon was connecting his LEDs in parallel, then adding a series resistor. 

I'm surprised that the seller offers resistors for 5V operation. I usually see listings mentioning (1k) resistors for 12V operation.

[mmagliaro]

Yes, the mystery's explained.  No, four white LEDs and resistor all in series would not light up from 5V, but Leon was connecting his LEDs in parallel, then adding a series resistor. 

I'm surprised that the seller offers resistors for 5V operation. I usually see listings mentioning (1k) resistors for 12V operation.

I was thinking parallel, they still might not light up.  If they have a forward voltage around 3, we get 2/300 = only 6 mA through the resistor.  6mA split 4 ways *might* light them up, but it's pushing it.

[peteski]

I was thinking parallel, they still might not light up.  If they have a forward voltage around 3, we get 2/300 = only 6 mA through the resistor.  6mA split 4 ways *might* light them up, but it's pushing it.

I can state from my own experience that white LEDs produce quite a bit of light, even under sub-milli Amp currents.

[dangerboy81]

Just to close out this thread, I thought I would show you the end result. Still a lot of work to do, but you get the idea. Thanks everyone for the help!