Capacitor filter for giving power to flickering LEDs

Post by **marshallh** » Mon Sep 26, 2005 8:25 pm

My LED backlight thingy has been flickering very faintly when the N64 draw large amounts of current (like rendering lots of polygons) and I wondered if a small capacitor across the led terminals would help. I know that capacitors are used across the terminals of small DC motors to prevent sparks, but would this even work for LED's?

Turbo Tax 1.0 · Post by **Turbo Tax 1.0** » Mon Sep 26, 2005 8:48 pm

iu have no idea but im likin your avatar and it looks good so far

daguuy · Post by **daguuy** » Mon Sep 26, 2005 9:14 pm

i think that should work

codeman · Post by **codeman** » Tue Sep 27, 2005 9:18 am

yeah, if they flicker briefly, and don't dim for a long time, then a cap would work. I couldnt tell from your picture if you were running it off of the wall plug or not. If you're using your own regulators, putting a big cap close to the regulator from +3.3 to ground would help also.

Post by **marshallh** » Tue Sep 27, 2005 3:57 pm

Yes, I'm running it off of 10 AA batteries. I'm using my own regulators and lastly, does the voltage of the capacitor matter? Does it simply have to greater than what woltage you are working with? And what value would you recommend starting out with?
And would a electroytic or ceramic capacitor be better?

Thanks for answering my questions.
Here's a better picture:
http://img331.imageshack.us/my.php?image=img00453nu.jpg

Marshall

usbcd36 · Post by **usbcd36** » Tue Sep 27, 2005 4:40 pm

I've had the same problem with my LED mod, even when running it off wall power. The solution I believe will work for me is to change where one of the trios of LEDs attaches, and instead switch that resistor to the other 7805.

Post by **marshallh** » Tue Sep 27, 2005 5:22 pm

usbcd36 wrote:I've had the same problem with my LED mod, even when running it off wall power. The solution I believe will work for me is to change where one of the trios of LEDs attaches, and instead switch that resistor to the other 7805.

To the "other" 7805? What screen are you using? I don't think anyone else is using tha same screen as me (Audiovox DVD screen)

daguuy · Post by **daguuy** » Tue Sep 27, 2005 5:55 pm

he's talking about psone screens. maybe you could connect the resistor for the LEDs to the 7805 on the N64 mobo

Post by **Gamelver** » Tue Sep 27, 2005 8:11 pm

yeah, a cap should fix the problem....what it does is it simply keeps the voltage at the right level if it ever goes down (causing a flicker)...

S q u e e ! · Post by **S q u e e !** » Wed Sep 28, 2005 7:48 am

What value? My PSone screen has flickered lately, and this sounds like an interesting fix.

codeman · Post by **codeman** » Wed Sep 28, 2005 7:59 am

marshallh wrote: I'm using my own regulators and lastly, does the voltage of the capacitor matter? Does it simply have to greater than what woltage you are working with? And what value would you recommend starting out with?
And would a electroytic or ceramic capacitor be better?
Marshall

yeah, a good rule of thumb for choosing a capacitor voltage is to make it's capability at least 30% higher than whatever voltage you will be using. So just dont get any 6.3v caps. Anything 10v or above is really common, and will work.
As for the type, you should use electrolytic. The ceramic ones only come in small sizes (unless you want to spend a lot of money), and you want something like 10-100 microfarads across the LEDs. The closer you can put them to the LED's the better, and electrolytics can be pretty small, and radio shack usually has them, so have at it!