[HELP] Connecting 2 sets of LEDs through transistors

Ok so I purchased 2 sets (blue and red) of 300 leds each, I connected each set through its own FQP30N06 transistor.

The Problem: Individually both sets work, when trying to turn them both on only RED lights up. I also noticed that if I turn BLUE ON and RED OFF, the BLUE will start to fade when the RED gets brighter.

After some testing without an arduino I found out that if I connect both of them (in parallel) to the battery (no transistor), the same problem occurs. I tried adding some resistors to the RED leds which now allowed me to turn both leds ON but they were at a lower brightness than before.

How do I fix this? I feel like there should be an easy fix.

Thanks

I tried adding some resistors to the RED leds which now allowed me to turn both leds ON.

That's the correct thing to do.

but they were at a lower brightness than before.

ie. You were overdriving them before (and they would eventually burn out).

Unless stated otherwise, LEDs run at 20 milliamps. Do NOT exceed that, add resistors as needed to bring them down to that current.

The forward voltage of an LED depends on the colour, the brand, the temperature - basically
if you connect them in parallel they won’t share current.

Yah but you dont understand, they were A LOT dimmer, Not sure which resistors I used (forgot the tester at work) but for leds they were both way too dim. Would it have anything to do with the fact that im using a 9V battery instead of 12V (which is what they're made for)? Im waiting for my 12V converter to come in the mail so I have no choice for now.

EDIT: These are the lights: http://www.ebay.ca/itm/350654019901
and these: Un-waterproof Blue LED Strip 3528 SMD 300LED 5M Flexible Lamp Light 60LED/Meter | eBay
EDIT2: I hooked it up to a car battery and it works great. Im guessing because they're diodes they do in fact need 12V to work and since im using crappy 9v batteries (some which are practically dead) they just didnt have the power it needed.

Thanks for steering me in the right direction guys, I appreciate it :slight_smile:

syst3mboot:
EDIT: These are the lights: http://www.ebay.ca/itm/350654019901
and these: Un-waterproof Blue LED Strip 3528 SMD 300LED 5M Flexible Lamp Light 60LED/Meter | eBay

Oh, now you tell us...

Those strips don't need extra resistors, they have built in resistors to work at 12V.

syst3mboot:
Would it have anything to do with the fact that im using a 9V battery instead of 12V

Yes.

You'll also need about 2 amps per string. A 9V battery isn't going to put out 2 amps, not even close.

Whatever 12V power supply you've ordered, I hope it's at least 8 amps unless you want it to overheat.

yah lol 500maH, so wasted $2 xD ... well the supply is only for testing the individual parts of the circuit, after i realize what im doing Ill order a mega, connect everything together and throw it into my car, car batteries are at about 50-75aH so im good :smiley: