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Building a better desk light


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This project was inspired by the work of another Blue Roomer whose post I now can't find, but it dates back a few years and was a similar LED strip desk light.


I've been disappointed for a while at the conventional methods of illuminating a mixing desk. LED gooseneck's just don't provide the even coverage needed - especially cheap ones. I priced up some more expensive littlelite ones when I purchased my new desk about a month ago, but decided that for the money, I could probably do better myself. I also had a slightly scary experience a year ago where I temporarily lost the eyesight in my right eye - probably a result of lifting, but I'd also spent the week looking at a very dark mixing desk, then looking up towards a very bright stage and back again - eye strain and headaches were the order of that week!


So, I designed my new desk light;


The work I do is quite varied - some theatre work where keeping it as dark as possible at Front of House is helpful, and some live music where actually I'd prefer the desk to be a little brighter. The light would always be used with my Roland M480, so it could be a custom build (though as it happens, by chance, it also fits an M7CL-48). I wanted some control over the warmth of the light - that blue tinge LED light isn't particularly pleasant to be working in. I also wanted to keep the light source out of sight, and preferably under my eyeline, so I was looking over the light at the stage and not having any light bleed upwards at me.


I turned to Ebay, and chinese suppliers in order to help my budget! I bought a pair of 50cm LED strips, one warm white, one red. The total of these two items with postage to the UK didn't come to much more than a tenner. I also bought a pair of PWM motor speed controllers to use as dimmers. Finally I bought a pair of plastic project boxes, some sticky back felt and some aluminium stock.


I decided to build affectively a football goal post, standing about 8 inches off the console and full width of it.


I attached the 2 LED strips side by side in a 60cm long 1" aluminium channel - this forms the cross bar. In the ends I cut some aluminium blocks which I bolted in place and tapped a 5mm thread in to the ends. Knurled nuts attach the cross bar to the verticals, which are rectangular aluminium tubes (containing the wires). At the bottom of these uprights are the 2 plastic project boxes. I bolted another pair of aluminium blocks inside these, which again have knurled nuts, attaching one project box to the bottom of each upright. The project boxes contain a dimmer each - one for red, one for white. They also contain a small neodynium magnet which attaches the project box to the console (the surface of the box being lined with sticky back felt to cushion the surface.


Power comes in via a wall wart supply, in to one project box where it splits, one feed locally to the white dimmer, the other going across the cross bar and to the red dimmer on the other side. Each dimmer output is then wired to its' respective LED strip.


One of the great things about putting the LED strip in a channel is that it gets a hard edge, so it's possible to accurately position where your light ends - preventing spill in to the audience. As the red and white strips are next to each other, their beams do differ slightly, so changing between red and white moves the hard edge forward or backwards, but I don't see it as a major problem.


So far it's working a treat. I've only got photos of it in situ, but once the show's over I'll post some more close ups of the actual construction. There are some chips on the paint finish, mainly because painting aluminium without acid etch primer isn't advisable, but mainly because it was painted before assembly so I've taken chunks out of it while I was wiring it up on the bench. After this show it's going in for a touch up and maybe some lacquer.


Apologies for this slightly blurry photos, they don't really do the light coverage justice. Remember that these are taken at full brightness - it's dimmable right down to nothing if needed.


So, firstly my chosen running setting for this week's panto - white with a hint of red to warm it up a bit.



Next, full white, no red



Next, full red



And finally from the back, showing the two project boxes and dimmer knobs. Sadly the cross bar is a little tricky to see against the console but it's there somewhere!





I reckon the whole thing has cost me less to build than one littlelite - and I've still got the gooseneck socket spare on my console, which is why you'll see one plugged in to the console in that last photo - it's lighting my script.

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Can you post the Ebay links of the LEDs and speed controller?

I've looked at Ebay for such items, usually a huge range. Bought some LED strips but was very disappointed with their output.



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The red ones came from;

CK Store

The warm white came from

Leon Lighting

And actually thinking about it, Leon are a UK business. I got 2 50cm warm white strips in a pack.


I've had to link to the stores in both instances because the items I bought have both now finished and aren't shown as relisted. Sure they'll be in there somewhere though.


The speed controllers are found here


Another addition I made was to add a bridge rectifier on the input. The original plan was to power this unit from the desk lamp socket via a short jumper cable, but as the desk already has a PWM dimmer on the lamp output, I thought the risk of PWM dimming the PWM dimmer (with unknown effects) was a bit much. As Allen and Heath (my other console) and Roland/Yamaha use different polarities, the bridge rectifier is just in there to make sure it'll run with both.

With a DVM in line and both LED's at full, the unit runs 440mA. I'm currently using a 15v supply though - partially because of the loss across the bridge rectifier. Not tried it on 12v, but pretty sure it'd work ok. If it didn't then you could just remove the bridge rectifier and make it specific to one desk manufacturer.


What's impressed me most about it is the lack of spill it generates. Looking at the top picture, the spill on to the desk and keyboard is from the script gooseneck, not the desk light. The theatre is pitch black and as you can see from the macbook in the left of the picture, the area directly around the desk is pretty dark too, yet the console is perfectly readable. You'll notice a tinge of red towards the top of the desk - this is what I entioned in the first post - the red and white LED's are sat next to each other in the extrusion, so the beam is slightly different, but it does mean with some careful positioning you can wash the top half of the desk (and the screen) in red to prevent glare, then the surface itself in white to read LX tape labels. I'll pretend that I designed that feature in!

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Excellent work, Cedd, thanks for sharing.

I'll pretend that I designed that feature in!

You haven't quite got the artistic muse thing right yet, have you? Whenever Serendipity takes a hand and outcomes beneficial to the project are revealed it is the spiritual approach to creativity in the inventor revealed through process.

Or some such b0110cks, got away with it for years!

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Ah yes, that would be another homemade device!!! It's just a hacked numeric keypad inside. It's driving my main playback pc which is running some software written by a friend. He'll be releasing it at some point when it's finished. My device is set up to drive 3 playback decks, so the first 2 are playing backing track (in unison as a hot standby) and the second is doing sound effects.

There's a column per deck and it gives me play, stop, next track and previous track, plus the top row for num lock, delete, that sort of thing.

It's also backlit, though they're currently all lamps because I can't afford the LED backlights for them! I'm not using the backlight in this performance though.

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The Frontier AlphaTrack. Lovely tool.





Add a bit of home-written software that integrates it to PCStage: any AlphaTrack button can be configured to do any PCStage function, and the slidy left-to-right thing at the bottom scrolls the script. Have yet to make the knobs, fader or LCD do anything.

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Very nice cobbling Cedd...well up to your B&B falling petals no doubt.


And very nice idea for the external keypad too. If anyone is looking for a similar device then have a look at the Cherry website. I believe they have some keypads which are designed to have assignable keys...just the thing for Multiplay et al...if like me you end up with a distrust of the space bar "GO".

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Usefully, this software that my friend's written supports OSC as well as MIDI, on top of assignable keyboard shortcuts. In the future I'm hoping to build an Arduino based playback remote sending OSC commands, so it leaves the number keys free to use for..... well, typing numbers! It'd be a nice elegant solution as OSC is a network based system - so I could give a remote to a musical director in the pit, or trigger it from a switch on stage, all sorts of ideas open to me. Several remotes with a hub, redundant backup, 2 pc's running from one keypad - lots and lots of flexibility.


Of course, that's a project for a while off yet!



Had a slightly scary moment tonight with this desk light as it happens. Saw smoke whisps lit in the air between my lamp and the desk. Naturally straight away assumed that the source of the smoke was my console and promptly started feeling the back of it to see how hot it was and using a torch to look for the source. Turns out I'd not noticed the LX boys using smoke in the scene beforehand and it had drifted right to the back of the theatre. How to scare a noiseboy with a new desk!

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