GGG Micro V LED Question

[Easywider]

Just had a question , was just making sure that R20 , the 1k resistor , is the LED limiting resistor for the circuit , I wanted to run two 3mm LED's in series instead of the one for an idea I have with the enclosure & think I might have to experiment with a few other values to get the brightness I wanted , any advice greatly appreciated , ...link to the schematic below Thanks 

http://www.generalguitargadgets.com/pdf/ggg_microv_sc.pdf

[Kipper4]

Hi Easywider.
Series or parallel that's the question.
Have you a breadboard to try it?
If parallel give each led it's own CLR (current limiting resistor) adjust to taste.

[Easywider]

Thanks for the reply , will be running in series , wanted them to be the same brightness , would R20 be the resistor I'll have to adjust ? Just want to make sure .. also , would a change there effect the circuit in any way , aside from changing the brightness of the LED's..

[PRR]

Parallel, the LED with the lower Vf will hog most of the current, be brighter.

Series takes more voltage, but 2V LEDs on a 9V battery, you gotta lose some voltage anyway. Series will put the same current in both. Current is the primary influence on brightness.

If you need EXACT same brightness, you will have to select LEDs yourself. Run of the mill LEDs at the same current may vary 20%. This is usually not obvious to the eye.

That R20 1K resistor is already a lot of current for modern LEDs on dim-lit stage. Stacking the LEDs is not a large drop of current. You have not said a precise brightness level you need. I would expect a 2-LED stack to work fine. If not, the trim is obvious.

[Easywider]

Paul , Thanks for the info...real bright is not an issue , I just wanted to make sure thats the right resistor to mess with , & from what You told me it is.. just something bright enough to see is what I'am after , & I take it when You say Stacking , that means running them in series , ..correct ?