LED question about black widow ultimate

[dopedpanda]

Hello (again )

I posted a couple of days ago about me trying to mod my black widow to cherry black switches (from a steelseries 7g, R.I.P.)

But today i started to get bored and pulled the dissasambled black widow forward and tryed to measure the voltage over the leds, and to my surprise, its using 4,5v (must be usb power and some voltage drops across the board)

But isnīt this high?

I thought about changing it to green or something like that while i was working with the keys, but they run at something like 2,1-2,5 volts if i remember right? What do i do?

If i remember right, blue leds need around 3-3,5 voltage to funktion and 4,5 volt would kill em, but that doesnīt seem to be the case? Does it use some kind of smart funktion to make the leds light up and then flush the extra voltage away? (like a circuit in a computer for the power led and reset led)

[alaricljs]

Where did you measure this voltage?  Across 1 LED?

[dopedpanda]

From negative (ground i quess its called in english :smile: ) to the positive side (or anode) on the led, that shows 4,5 volts, if i measure across the LED (from anode to cathode) then it would only show the voltage lost over that singel LED.

[IvanIvanovich]

LED commonly come in several voltage. If your 4.5v measurement is accurate, you could always buy 5v LED in your chosen color. They would still work fine, just not 100% brightness, but at least you not have to worry about burning them.

[The Solutor]

From negative (ground i quess its called in english :smile: ) to the positive side (or anode) on the led, that shows 4,5 volts

This is not the correct way.

If you need to know the LED's voltage you must measure what's between its pins.

BTW they are blue LEDs so the voltage measured should be between 2.9 to 3.5V or so.

And is not the voltage that kills the led it's the current

[The Solutor]

See Sig>Mods>Trackball>LED 101 Tutorial for some good links.

IIRC Deck used the trick of running two LEDs in serial and then parallel the pairs.

Which is a good idea when one have to use red, amber, classic green leds, but is pointless when one have to use the normal Blue, Acqua, Ultrabrite Green, or white led, given they needs more than 2.5 V two LEDs in series will need more than 5V.

Otherwise to get Greens in you're gonna go nuts soldering in resistors.

Greens intended as the ultrabrite ones (the ones commonly available today) have more or less the same specs than blues and can be replaced w/o any resistor mod.

[jmw19]

LEDs are current sensitive, so Razer could simply be limiting the current to the LEDs, rather than trying to limit voltage. That actually makes more sense to me, since LEDs can exhibit markedly different current draws at the same voltage. Something to do with flaws across the semiconductor layers.

If that's the case, you could swap in pretty much any color LED you like, since the current across each will stay the same. I'd definitely test it out first, though - much easier to desolder one red LED than a board's worth.

BTW, I'm typing this on a BWU (hey, it was on sale, and I really wanted the option of illuminated keys. Very happy with it so far.)

[The Solutor]

so Razer could simply be limiting the current to the LEDs

BW uses a single resistor per LED, the most classic configuration.  Xarmor/Qpad uses one resistor for all the LEDs, Deck an odd H shaped circuit with three resistor every two LEDs

If that's the case, you could swap in pretty much any color LED you like, since the current across each will stay the same.

No you can't, if you replace a green led with a red one you will almost double the current, which is not harmful for the LED, because the driving current for the blue LED is keept well below the maximum tolerable, but can increase the board requirement above the maximum USB specs.

[The Solutor]

I think this is how Deck does it.

No it doesn't, this is impossible to work with blue  LEDs and 5V power supply.

http://www.deckkeyboards.com/documents/legend_schematic.pdf

[The Solutor]

This is for a Deck Red.

Look carefully, the schematic is meant for any kind of led, just some resistor values are replaced.

Should work for the green LED mod which I believe is what the OP wanted.

The OP has just to swap the leds. Unless he is going to use the old style ones which are not common nowadays, and are more expensive because less used.

[The Solutor]

I hate reading schematics.

The Deck schematic is designed by the "office for complicating simple affairs", and is designed by the "office for obfuscating further the design".

So you are basically right, here.

BTW this is is the Deck's schematic designed slightly better.

[ Attachment Invalid Or Does Not Exist ] 23842[/ATTACH]

[dopedpanda]

"This is not the correct way.
 
If you need to know the LED's voltage you must measure what's between its pins.
 
BTW they are blue LEDs so the voltage measured should be between 2.9 to 3.5V or so.
 
And is not the voltage that kills the led it's the current"

Oh, im just used to measure current/voltage on cars, but i give you credit for this one, 2,4 volt across the leds, so i should be able to change it into greens without a big problem (try with one or 2 first)

About me going trough with this, just let me say that im crazy, got a pretty good solder hand and tools and i like to stare at something for several hours

[The Solutor]

Oh, im just used to measure current/voltage on cars

You are used to measure voltage on cars with negative grounded, that nowadays are, more or less, the 100%. Until the sixties a lot of cars were positive grounded...

In the led case, very often the LEDs anode is connected to +V and the cathode is connected to the limiting resistor which is connected with  the active circuitry which , in turn is connected to ground.

But you can have variations, like resistor on the anode, active circuit on the cathode...

Oh, im just used to measure current/voltage on cars, but i give you credit for this one, 2,4 volt across the leds, so i should be able to change it into greens without a big problem (try with one or 2 first)

Yes, surely.

Btw, if you want a suggestion, use the white leds (here, warm white ones).



with white, you can change your mind w/o the need of soldering/desoldering anything

[dopedpanda]

How do you mean i can change the colour without desoldering anything?
Colour the keycaps?

[The Solutor]

How do you mean i can change the colour without desoldering anything?
Colour the keycaps?

Yes, I've just used the lumocolor pens, on the back of the keys and on the top of the leds, if you change your mind, some alcohol and a cloth are enough to clean the paint.

[elo820]

Yes, I've just used the lumocolor pens, on the back of the keys and on the top of the leds, if you change your mind, some alcohol and a cloth are enough to clean the paint.

I want me Bw to have red or something! Show what pen color for blue led under?

[The Solutor]

There isn't a pen or paint that can transform the blue light in anything else.

You can just filter the white light

[elo820]

There isn't a pen or paint that can transform the blue light in anything else.

You can just filter the white light

So I cant do anything to the BW leds right? What do you mean by filter?

[Quarzac]

OP, be sure to post if your mod goes well. I would like a green Blackwidow too, but don't want to be the first to do it, because then there is no one to warn me of the troubles I may have down the road.

[The Solutor]

So I cant do anything to the BW leds right?

You can directly replace them with white, new style green, acqua, pink LEDs, or you can replace them with old style green, yellow,amber, red leds replacing also the resistors.

What do you mean by filter?

Filter the lights, place something coloured between the led and your eye, the quickest way is touse the lumocolor pens, but the gel filters can also be used, a further alternative is represented by the microlamps coloured minicondom.