Author Topic: will this led be bright enough?  (Read 806 times)

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Narcosynthesis

will this led be bright enough?
« on: September 14, 2004, 11:16:28 AM »
http://www.maplin.co.uk/Search/Results.asp?CartID=04091422034467&Level=2&Menu=236&Name=5mm+12v+Standard+Leds&PrevMenu=16&PrevName=Optoelectronics

will this led be bright enough for use in a stompbox? it would be connected to only the power supply (the box is a passive kill box, this would only be for an on/off indicator) which would be 9v, so that supply wouldnt kill it but would it be big enough to see easily enough alongside other stompboxes?

or i could just get a normal led, but what resister would i need to keep the led intact but to let it be bright enough to see easily?

much thanks

David

Paul Perry (Frostwave)

will this led be bright enough?
« Reply #1 on: September 14, 2004, 02:22:48 PM »
Get a normal led, put 10K or so in series so you don't kill it, then a 100k or so pot, then connect to the power, then waggle th pot to suit, then measure what the pot and 10K add up to, then you know your resistor, then find one close to that, game over.

STOMPmole

will this led be bright enough?
« Reply #2 on: September 14, 2004, 09:35:10 PM »
I've used the LEDs from Smallbear and http://lsdiodes.com/ , both of which are plenty bright for pedals.

The Smallbear water clear blues and all of the lsdiodes LEDs are so bright I run them WELL under the 20mV they are rated at to avoid blindness while on stage!

Ge_Whiz

will this led be bright enough?
« Reply #3 on: September 14, 2004, 09:55:17 PM »
Based on experience, I doubt that 9V would light a 12V LED at all. I generally agree with Paul's suggestion but with lower values; 470 ohm for protection, 10K pot for adjustment using a normal or superbright LED.

Paul Perry (Frostwave)

will this led be bright enough?
« Reply #4 on: September 15, 2004, 01:23:40 AM »
Quote from: Ge_Whiz
Based on experience, I doubt that 9V would light a 12V LED at all.

I can't argue with experience! because, I have none in this case.
But, if all that there is inside the unit is a tiny resistor to limit the current, then it might work a bit with 9v. Of course, for efficiency, there might be 4 or 5 tiny led chips in series there as well, and 9 wouldn't get over the hump. Who the hell wants 12v led assemblies anyhow? Automobiles??

Narcosynthesis

will this led be bright enough?
« Reply #5 on: September 15, 2004, 11:04:29 AM »
using a pot to find a value for the resister wouldnt really work for me, as its pretty hard to get to maplins or order parts, so i want to try and get everything at the same time and not have to bother going back and forth

for a standard led, what resister do you use?

David

downweverything

will this led be bright enough?
« Reply #6 on: September 15, 2004, 01:12:33 PM »
(9-'forward voltage of led')/0.02=resistance


the 9 is from the 9V supply the .02 is the amount of current you want running through it (its usually 20mA hence the .02, if you want to save more battery power make it half or a fourth or whatever)