Rant: SMT LEDs on dev boards are way too bright! - Page 1
Forum section: electronics / general

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: January 21, 2016, 03:52:52 pm
content: Title says it all really, I've got a xilinx dev board and a TI ARM board for the edX course that starts this week on my desk. They both have dozens of little squares of tape stuck (several layers thick) over the LEDs to bring the brightness down to an acceptable level. The ARm one i'll probably swap out the series resistors for higher values.Why do the people who design dev boards make the LEDs so bright that you can't look anywhere near them without feeling like you're going to permanently damage your vision. Who is doing dev work in the midday equatorial sun or while wearing a welding mask?GRRRDoes anyone else find this or is it just me?

author: rdl
author_rank: Super Contributor
timestamp: January 21, 2016, 04:42:12 pm
content: Also annoying is when they use clear, point-source type LEDs instead of diffused. A blob of white glue with a little talc stirred in is good for fixing that.

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: January 21, 2016, 04:52:09 pm
content: Yep, The ones on this Xilinx board in particular are like lasers!

author: tszaboo
author_rank: Super Contributor
timestamp: January 21, 2016, 04:54:28 pm
content: It is not just you. I will start a petition to ban blue LEDs.ST-Disco boards also have this plague (disco!). I think it is because a bunch of students design these boards, who think that an LED has to be driven with 20mA (and they are soo good that they can even calculate the resistor for it). I hardly give more than 4-5 mA to an LED.

author: Thorondor
author_rank: Contributor
timestamp: January 21, 2016, 07:18:35 pm
content: Blue LEDs are at the top of my list of bad product design features - especially home theater equipment.

author: Zero999
author_rank: Super Contributor
timestamp: January 21, 2016, 07:44:05 pm
content: They're not all blue. Some green LEDs are extremely bright too.

author: Thorondor
author_rank: Contributor
timestamp: January 21, 2016, 09:47:32 pm
content: True, but dim red/green/yellow status LEDs usually aren't being replaced with brighter versions of the same color - they're being replaced by blue eye-scorchers.

author: diyaudio
author_rank: Frequent Contributor
timestamp: January 21, 2016, 10:01:56 pm
content: Quote from: NANDBlog on January 21, 2016, 04:54:28 pmST-Disco boards led looks like a U.S cop car

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 21, 2016, 10:20:25 pm
content: Design engineer sees "If = 20mA", puts in respective resistor, and,

author: cimmo
author_rank: Frequent Contributor
timestamp: January 22, 2016, 04:19:31 am
content: People (designers) need to understand the difference between an LEDindicatorand an LEDilluminator.

author: void_error
author_rank: Frequent Contributor
timestamp: January 22, 2016, 06:14:05 am
content: So far I've only needed rather small and simple dev boards so I made my own. Not a single LED current limiting resistor was calculated. I just used 1k or 1k5 for 5V supply and 680R to 1k for 3.3V and always used LEDs with matte (as opposed to transparent) case with the same color as the LED light - makes it easier know what color the LED is when it's off.As for 20mA per LED... that works quite well if your LEDs were manufactured in the 80s.

author: Zero999
author_rank: Super Contributor
timestamp: January 22, 2016, 09:16:47 am
content: Quote from: blueskull on January 22, 2016, 05:18:09 amRecently I've found my local supplier stocks pastel coloured LEDs; perhaps that's what you need?I haven't tried them. They all have the same forward voltage and are probably blue or violet LEDs with a phosphor mix to produce the desired colour.http://www.optosupply.com/EN/Product_shape.asp?sid=1&bid=101&i=1&pdid=0&#S101http://www.rapidonline.com/5mm-LEDs/TruOpto-5mm-Pastel-LEDs-15-551199

author: tszaboo
author_rank: Super Contributor
timestamp: January 22, 2016, 09:23:25 am
content: Quote from: cimmo on January 22, 2016, 04:19:31 amPretty much. Farnell puts the LEDs into two different category, one is for high brightness(not that anyone will order that from them) and standard. If someone is putting a not diffused LED on a dev board, something is done bad. It is also possible that the BOM is butchered by the supply chain, replacing it with the cheapest LED possible.It is quite ridiculous, that I need to put insulation tape over the development boards (and sometimes monitor indicator or other consumer electronics), otherwise my eyes are in pain every time I look there.

author: TerraHertz
author_rank: Super Contributor
timestamp: January 22, 2016, 11:00:22 pm
content: Better than tape - the appropriately named Blutack. Mold a small piece over the offending LED, then make a small pinhole through to the LED. Squish to adjust brightness. It also sticks better than tape, and if you do it neatly it can even look like it was supposed to be there.Or, you could just replace the resistors. Probably in less time than it took to post. Also, why no pics?There's so much irony in complaining about overly efficient LEDs.Currently waiting on some 3mm warm-white LEDs from Hong Kong, to replace lots of tiny filament bulbs (dead) in an old scope. It's starting to look like this will be the first ever 'non-arrival' I've had with Asian buys.

author: eugenenine
author_rank: Frequent Contributor
timestamp: January 22, 2016, 11:29:50 pm
content: Its was D. Head's idea after Dave complained about the LED's being too dim.

author: German_EE
author_rank: Super Contributor
timestamp: January 23, 2016, 05:58:00 pm
content: Guys, guys, here's what you need to do to solve this particular problem.1) Get a girlfriend (or a wife if you must)2) Borrow her nail polish and put a dab on each LED. If you want to attenuate the output a little then use the same color as the LED but if you really want to turn down the lights use blue nail polish on red yellow or green and red nail polish on blue LEDs.

author: Len
author_rank: Frequent Contributor
timestamp: January 23, 2016, 06:19:41 pm
content: Quote from: German_EE on January 23, 2016, 05:58:00 pmIn many countries, it is now legal for men to buy nail polish.

author: Len
author_rank: Frequent Contributor
timestamp: January 24, 2016, 02:39:13 am
content: Quote from: blueskull on January 24, 2016, 02:30:32 amNo. It was supposed to be a joke.

author: AlxDroidDev
author_rank: Frequent Contributor
timestamp: January 24, 2016, 07:00:36 am
content: Blame it all on an Aussie bloke called Dave Jones. After he complained that the PICKit 3 had dim LEDs, everyone started shipping products with extremely bright LEDs.Legend has it that the new revision of the PICKit 3 can be seen from the ISS when all its LEDs are on.

author: fivefish
author_rank: Frequent Contributor
timestamp: January 24, 2016, 07:15:40 am
content: If the LEDs are bright, it means the Dev Kit is really powerful...The brighter the LED, the more powerful, faster, smaller, feature-rich the dev kit is.yeah....and if it's blue, it's way cooler than the other old boring dev kits using red or green leds. What is this? The 80s?

author: kingofkya
author_rank: Regular Contributor
timestamp: January 24, 2016, 09:36:45 am
content: Quote from: NANDBlog on January 21, 2016, 04:54:28 pmThat sounds like a bit mutchunder 1ma on the green and blue leds. some of thouse generic china leds are stupid bright now

author: Psi
author_rank: Super Contributor
timestamp: January 24, 2016, 09:47:19 am
content: One of the automotive products i sell has some high intensity LEDs on the front. I have 30k resistors on them! (from 5V)Then i 8bit PWM that to get them dim enough for 'night mode'

author: AlxDroidDev
author_rank: Frequent Contributor
timestamp: January 24, 2016, 09:52:18 am
content: Quote from: fivefish on January 24, 2016, 07:15:40 am+1After all, nothing says "bleeding edge, state-of-the-art high tech" like a bunch of blue LEDs driven with 50mA DC, with absolutely no labels indicating what they mean. Blue is the new red, pink is the new green. Red and Green are so 80's they belong in a History Channel documentary, not in a high tech product. They are so out of fashion that RGB should just become PVB, for Pink-Violet-Blue, which are really cool colors for LEDs, and a trend for this season.

author: cimmo
author_rank: Frequent Contributor
timestamp: January 25, 2016, 07:04:18 am
content: I've just built a PC (the one I'm using to write this) and the case (Deepcool Smarter) front panel LEDs were typical searchlight blue. The included case fans even had blue LEDs. Before putting any hardware in this case, all those boring and blinding blue bling LEDs were removed and replaced with red, orange and yellow LEDs.Since finding the USB and eSATAp ports (front or back) is a lottery when the unit is hiding under a desk, I have installed LEDs behind them so they can be found easily in the dark (yellow for USB3/eSATAp, orange for USB2 and red for USB sockets for which I had no more motherboard interfaces - these are wired up directly to 5v (no data) to be used for charging purposes.The blue LED backlighting for a media card hub/fan controller/temperature display was also replaced with a much more eye friendly yellow LED.On an unrelated note (nothing to do with overbright LEDs), I've also put in a row of DC power jacks on an expansion slot cover plate so all the external devices (HDDs and powered speakers) can be powered from the 12v rail from the PC's power supply, avoiding all that mess associated with half a dozen wall warts and their overly long cables.