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Rotary encoder backlighting made easy!


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Hi there!

I just completed a build of the MB6582, and during construction I designed a small PCB to neatly hold some backlight LEDs for the rotary encoders.
The PCB source files and installation details are all available here on my GitHub page, licensed under Creative Commons so that anyone is free to order their own or change it:  https://github.com/dwhinham/encoder-backlight-pcb

I have about 9 spare sets of 15 PCBs if anyone would like some. :happy:

Shoutout to @Hawkeye for the inspiration and excellent control surface construction guide!
I've got more pictures and a video of my MB6582 over on Twitter if you'd like to see: https://twitter.com/_d0pefish_/status/1295104812678291465






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  • 3 months later...

I finally got a chance to build and integrate these awesome encoder backlighting PCBs.

With such a clever and functional design from @d0pefish, I had no excuses!

The one impediment for me was having to learn some basic SMD soldering, but @Hawkeye's videos on the subject made it much easier ;-)

I'm currently powering the lights with a 9v source, but I think this makes them a bit too bright and they illuminate the whole bottom half of the control surface.









Edited by dwestbury
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Yes I agree with Hawkeye, beautiful work!

Curious, how taxed does all this make the 5V rail? I was looking at LED choices (should I be unable to repair my old control surface and have to solder together a new one) and the number of LEDs on the panel given each LED's mA had things at like 2.7A if I did my math right. That's well above the 1A max of a typical 7805? I'm using the fancy 5V switching regulator now often recommended but back when the MB6582 first hit the scene as it were, a regular 'ole 7805 was the norm. Seems like it worked fine as far as I have seen, but curious?

Sorry kinda hijacking the thread here but since the LED knobs add even more power draw, thought I might ask the question. Definitely has me thinking about doing lighted LED knobs though, they're awesome!

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Encoder backlighting could add as much as ~840mA in power draw to your MB-6582 (e.g., ~14 encoders with 3 * SMD LEDs @ 20mA peak ea.)

Before I decided to go for it, I measured the total load of my MB-6582 @ ~650-700mA, which included the mainboard (with 8x 8580 R5 SIDs) and the standard fully populated control surface.

My build is using the RECOM 5v SREG @ 1.5A (mouser:  919-R-78B5.0-1.5), which still has plenty of headway, but I decided to tap into the 9v line anyway, based suggestions in Dale's documentation (https://github.com/dwhinham/encoder-backlight-pcb).

As I mentioned above, 9v seems to be a bit much for my taste, because *the lights are blinding*... So, I'll probably look to step that down to find the sweet spot.


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On 12/11/2020 at 9:08 AM, d0pefish said:

Yes - you definitely want to experiment with resistor values before you buy a whole bunch of them and solder up all the boards. For my yellow LEDs, they were bright, but not excessively so - your mileage may vary depending on LED specifications. :)

Couldn't agree more... In hindsight I made 2 rookie mistakes: 

1) only buying the 150 ohm SMD resistors (leaving myself with no choices) and...

2) testing with a 6.6v battery source, because I was only concerned with functionality and I didn't even think about final state brightness levels while I was building


Now I'm thinking that a useful course correction could be to install one of these thumbwheel pots into the side of my case, since that would allow me to adjust the LED levels to taste, depending on room brightness, etc.


Keep everyone posted if I ever get there ;-)




Edited by dwestbury
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