i have got today my RGB LEDS cathodes
so i took 4 cathodes, than wired them together, + - + -
than cut off a molex head took the red cable (+12v) and wired him to -
and the black cable (-) to the last + cathode. after all this i used soldering iron.
than i turned on my pc and nothing, no circuit working. what i did wrong ?

these the cathodes here
and how they work

sorry for my english :/

 

i have got today my RGB LEDS cathodes
so i took 4 cathodes, than wired them together, + - + -
than cut off a molex head took the red cable (+12v) and wired him to -
and the black cable (-) to the last + cathode. after all this i used soldering iron.
than i turned on my pc and nothing, no circuit working. what i did wrong ?

these the cathodes here
and how they work

sorry for my english :/

I am not sure how you connected them, but be glad they didn't light. If you didn't use current limiting resistors, they would have burned out.

Post a diagram of how you connected them. It doesn't have to be pretty.

 

You need 510 Ohm resistors as well.

 

You need to wire the cathode to -ve , and the anodes to +ve, use a 470 ohm resistor in series on each anode and then connect it to the power supply and then they will work.

 

If you didn't use current limiting resistors, say bye-bye to your LEDs.

Luckily, you wired the power to the LEDs backwards so nothing happened.

 

You need 510 Ohm resistors as well.

You need to wire the cathode to -ve , and the anodes to +ve, use a 470 ohm resistor in series on each anode and then connect it to the power supply and then they will work.

If you didn't use current limiting resistors, say bye-bye to your LEDs.

Luckily, you wired the power to the LEDs backwards so nothing happened.

guys. i dont have resistors, and i dont know whats that. look i am really amateur in electronics .

here's the diagram

so whats the problem?

 

Amazing that you learned about LEDs before resistors!

It's time for you to click on the first tab at the top of this page!

 

Amazing that you learned about LEDs before resistors!

It's time for you to click on the first tab at the top of this page!

ok, i really need to learn about electronics
but look man i just followed this tutorial, watch the whole video
he didnt say anything about resistors
http://www.youtube.com/watch?v=IHKo5XxizpY&list=FLJ1YyhsNCFWgxSGm0SsFDTw&index=3

 

That YouTube video gives bad advice and the guy doing it clearly knew nothing about LEDs or electronics.

The item he copied probably had a resistor under the heatshrink.

Anyway you still wired them backwards and to the wrong voltage wires. The yellow is your +12v and the black your 0v. You'll need a resistor for each colour of led.

If you do not use a resistor in a led circuit one of the devices will hog all the current and eventually fail. It might only take seconds, or could be hours but one will blow.

There are led resistor calculators on the Internet that will give you the correct values to get, based on the configuration you want.

I might go something like
+12v ----->|----->|----->|----330ohm-----0v for red led
+12v------>|----->|----->|----220ohm-----0v for green led
+12v------>|----->|----->|----150ohm-----0v for blue LEDs

Or resistor values close/slightly higher.

 

That YouTube video gives bad advice and the guy doing it clearly knew nothing about LEDs or electronics.

The item he copied probably had a resistor under the heatshrink.

Anyway you still wired them backwards and to the wrong voltage wires. The yellow is your +12v and the black your 0v. You'll need a resistor for each colour of led.

If you do not use a resistor in a led circuit one of the devices will hog all the current and eventually fail. It might only take seconds, or could be hours but one will blow.

There are led resistor calculators on the Internet that will give you the correct values to get, based on the configuration you want.

I might go something like
+12v ----->|----->|----->|----330ohm-----0v for red led
+12v------>|----->|----->|----220ohm-----0v for green led
+12v------>|----->|----->|----150ohm-----0v for blue LEDs

Or resistor values close/slightly higher.

between every 2 cathodes should be 1 resistor ? so how many resistors should be in 4 LEDS circuit ?

 

No you only need one in such a case.

Why do you want to wire them in series?

The single colors as such share a cathode.
You need one resistor for each color.

If you wire more LEDs in series, normally you need only one resistor.

 

Ah yes if they are common cathode then the resistor needs to be on the anode side.

First work out how you want them wired. Having a few LEDs in series can reduce the amount of power used by your circuit and also the amount of energy wasted as heat.

And in my ASCII circuit there were 3 LEDs in series, not two.

 

Ah yes if they are common cathode then the resistor needs to be on the anode side.

First work out how you want them wired. Having a few LEDs in series can reduce the amount of power used by your circuit and also the amount of energy wasted as heat.

And in my ASCII circuit there were 3 LEDs in series, not two.

can you show me a diagram how should be the circuit with the resistor and the 4 common cathodes? it will help