RowanHall Posted February 9, 2011 Report Share Posted February 9, 2011 Hi all, Just starting back at finishing my control surface for my sid after a break of 6 years! Sid is a v1, 4 core, fully working up to step B, with mios 1.8 and sid 1.7a. I am planning on using the ultrabrite blue leds with the standard resistors. Just wondering if it was possible to add some sort of dimmer pot that would control the brightness of the leds attached to the dout, to save my eyes from the leds? Any advice greatly appreciated! :) Rowan! :) Quote Link to comment Share on other sites More sharing options...
nILS Posted February 9, 2011 Report Share Posted February 9, 2011 I am planning on using the ultrabrite blue leds with the standard resistors. Just wondering if it was possible to add some sort of dimmer pot that would control the brightness of the leds attached to the dout, to save my eyes from the leds? Notice something? Pick one: a) Change the resistors to something more suiting (like 22k) b) Add a 20k pot in between every DOUT pin and its LED c) Choose decent LEDs. Blue bad. Ultrabright blue very bad. Blue bad. Quote Link to comment Share on other sites More sharing options...
RowanHall Posted February 9, 2011 Author Report Share Posted February 9, 2011 (edited) I decided to keep the standard resistors to keep the LEDs less bright, hence why i mentioned it, is this practice alright? How much further would the resistors you suggested dim the LEDs? I don't have to use the blue ones, just thought I would as I had some to hand, howcome they are so bad? Rowan Edited February 9, 2011 by RowanHall Quote Link to comment Share on other sites More sharing options...
phunk Posted February 9, 2011 Report Share Posted February 9, 2011 (edited) I decided to keep the standard resistors to keep the LEDs less bright, hence why i mentioned it, is this practice alright? No, that doesn´t make sense. A standard LED resistor has a value between 220 and 500 Ohm assuming a standard LED and a 5V voltage. That limits the current to about 20mA, a standard value. To dim a blue LED or a ultrabright blue LED you need a much higher resistor value than a standard value because you have to limit the current to about something around 1mA. So start with 20k like nILS suggested. How much further would the resistors you suggested dim the LEDs? Depends on a lot of things. You cant tell without trying. I don't have to use the blue ones, just thought I would as I had some to hand, howcome they are so bad? because of the spectrum of the light they emit. There are no blue leds that arent bright or ultrabright. Honestly they suck in applications like this... Edited February 9, 2011 by phunk Quote Link to comment Share on other sites More sharing options...
Imp Posted February 9, 2011 Report Share Posted February 9, 2011 (edited) Blue LEDs emit lots of energy within a small bandwith, so when you realize they are slightly too bright, they might already damage your eyes. Just connect one LED with it's resistor+ a pot, and tweak until you like it. Then measure the combined resistance and replace all resistors accordingly. But keep in mind, that usually you'll have like 20 LEDs lit at once :wink: edit: dammit, too slow ;) Edited February 9, 2011 by Imp Quote Link to comment Share on other sites More sharing options...
RowanHall Posted February 9, 2011 Author Report Share Posted February 9, 2011 (edited) Ah of course, that does make sense! It would have paid to bother reading the datasheet! :) I do have some 20k ohm resistors lying about and will test it out tomo. Likely i suppose the installed 220 ohm resistors would probably end up eventually damaging the blue LEDs? I think I'll probably just use the red as I'm less likely of being blinded! Haha! :) Edited February 9, 2011 by RowanHall Quote Link to comment Share on other sites More sharing options...
RowanHall Posted February 9, 2011 Author Report Share Posted February 9, 2011 Just connect one LED with it's resistor+ a pot, and tweak until you like it. Then measure the combined resistance and replace all resistors accordingly. Great idea for determining the resistance! Just what I needed to hear! Thanks! :) Quote Link to comment Share on other sites More sharing options...
nILS Posted February 10, 2011 Report Share Posted February 10, 2011 Also, if you really must use blue LEDs at least do the following: Make a little test panel thingie out of cardboard or the likes with 5-10 LEDs. Trim the brightness until you like it. Then set the lit LEDs right next to your computer screen. If they don't bug you after 30 minutes raise the resistors by another 5% and you're good. Quote Link to comment Share on other sites More sharing options...
RowanHall Posted February 16, 2011 Author Report Share Posted February 16, 2011 Also, if you really must use blue LEDs at least do the following: Make a little test panel thingie out of cardboard or the likes with 5-10 LEDs. Trim the brightness until you like it. Then set the lit LEDs right next to your computer screen. If they don't bug you after 30 minutes raise the resistors by another 5% and you're good. Thanks for the good advice nILS, will certainly try that. Cheers! :) Rowan Quote Link to comment Share on other sites More sharing options...
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