4 LEDS for multi-FX unit, only two work at a time??

[Styles]

Hello-

Still pluggin away on my multi fx unit i'm working on.  I started with the LEDs and my plan was to run a single 9v lead to all LEDs and then ground with a single ground wire snaking to the same post on the switch.  Only two LEDS will work at a time now, either the left pair or the right pair- what the heck am I not getting??  Thought this would be a great way to have to run only one 9v and ground for the whole LED setup.  Here's my layout:

[Jdansti]

Any current limitting resistors in your LED circuit?

[Styles]

yeah, 1k, and i'm just hooking up to a battery to test right now

[kurtlives]

You need 1 RCL per LED.

[Styles]

so sticking one 1k resistor between the PSU and chain of LEDs won't work?  Is that why they only work in pairs?

[mremic01]

That resistor isn't letting enough current through to light up more than two at a time. Does one LED get dimmer when you turn on a second one? That's what I'd expect would happen if you've got a single resistor between all the LEDs and the power supply. Give each LED its own resistor and they should work independently. If you're using different colors, you might have to mess around with resistor values to keep some LEDs from being a lot brighter than others. I usually use something like 3.9k for reds and 10k or so for blues.

[Gurner]

yes on resistor per LED is necessary. Assuming your colour scheme is correct, this will get you in the ballpark at in or around 8-10mA per LED...

Yellow LED use a 1k resistor

Red LED use a 1 k resistor

White LED use a 680R resistor

Blue LED use a 680R resistor

If you want them brighter, then lower the values a bit.

[Styles]

oh duh, this totally makes sense why this isn't working..rather than one resistor before the whole chain, i needed to do this instead:

thanks so much for the help!!