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geekhack Projects => Making Stuff Together! => DIY Discussions ARCHIVE => Topic started by: himynameisbunny on Thu, 31 March 2011, 23:17:22

Title: Inserting LEDs into Cherry switches?
Post by: himynameisbunny on Thu, 31 March 2011, 23:17:22

Hey guys.

I've tried looking around for information but all I can find is Ripsters' post here:

Quote

Inserting the LEDs is straightforward. All Cherry MX switches have two holes for a 3mm LED. Pop them in from the top and you're done.

Show Image

(http://geekhack.org/attachment.php?attachmentid=8543&stc=1&d=1269012149)

My question is, is it possible to retrofit LEDs to Cherry switches? I know that on the switch shell the provision is there as above, but I'm guessing it depends on the PCB design on whether or not you can get them to work?

Cheers.

Title: Inserting LEDs into Cherry switches?
Post by: Mr. Perfect on Thu, 31 March 2011, 23:52:51

I've been wondering the same thing. There might be a snowball's chance in hell if you've got a board that features in-switch diodes, since the PCB would have holes for mounting in. The question then is whether the board can supply power to the LEDs and if there is a resistor somewhere to keep those LEDs from a thermal run away (http://www.google.com/search?q=led+thermal+runaway&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a).

Title: Inserting LEDs into Cherry switches?
Post by: himynameisbunny on Fri, 01 April 2011, 04:42:13

So you don't think it's that likely that you could make it work?

Having said that it would be a way to make your BlackWidow Elite a ghetto Ultimate I suppose.

Title: Inserting LEDs into Cherry switches?
Post by: kps on Fri, 01 April 2011, 11:21:38

Quote from: Mr. Perfect;322521

I've been wondering the same thing. There might be a snowball's chance in hell if you've got a board that features in-switch diodes, since the PCB would have holes for mounting in. The question then is whether the board can supply power to the LEDs and if there is a resistor somewhere to keep those LEDs from a thermal run away (http://www.google.com/search?q=led+thermal+runaway&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a).

The matrix diode holes are different from the illumination diode holes. If you replace a keyboard's diodes with LEDs, they would only be illuminated when the key is pressed, and since the matrix is scanned, they'd be run at a duty cycle of 1/8 or 1/16 or whatever, so you wouldn't need resistors.

Quote from: himynameisbunny;322590

Having said that it would be a way to make your BlackWidow Elite a ghetto Ultimate I suppose.

The BWs share the same PCB -- the non-ultimate has holes for LEDs and pads for resistors -- so someone could try a conversion.

Title: Inserting LEDs into Cherry switches?
Post by: himynameisbunny on Fri, 01 April 2011, 20:45:31

Sorry Ripster, that's the part that I didn't understand - whether or not the resistors were there for the keys themselves or for the LEDs, and whether or not they were needed.

So in that case they are needed? And I'm assuming there has to be space in the board for it?

Title: Inserting LEDs into Cherry switches?
Post by: kps on Fri, 01 April 2011, 23:01:44

Quote from: ripster;322768

Not enough forward voltage on a scanning matrix.

Blue LEDs are so 2009.

(http://geekhack.org/attachment.php?attachmentid=16557&stc=1&d=1301716203)

In theory you are right — a LED has too much drop to stay inside the receiver's voltage thresholds. In practice, a 2V red LED will probably work with a typical 5V CMOS controller ("probably" means "not my problem"). For CMOS with TTL-compatible inputs, anything but blue and white would probably work (the matrix must drive high or else plain old dark diodes wouldn't work either).

Also in practice, it's a pretty pointless exercise, since the LED only illuminates when the key is pressed, and the duty cycle is low. But I said that already.

Title: Inserting LEDs into Cherry switches?
Post by: keyboardlover on Fri, 01 April 2011, 23:08:25

Very easy mod to do on a Poker (http://deskthority.net/viewtopic.php?f=4&t=125), apparently.

(http://i.imgur.com/WVpUM.jpg)

Title: Inserting LEDs into Cherry switches?
Post by: AcidSouL on Sat, 16 April 2011, 04:53:45

please if someone try and success put diods in BW elite...to explain here how do it :)