A Shinning Light for the NXTCam Camera

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I’ve been experimenting with my new Mindsensor NXTCam. As most people are aware of the inherent issues associated with optical sensing, mainly due to changes in lighting level, can be very frustrating. In attempt to minimise this lighting issue, I decide to construct a stable light source for the NXTCam. To begin, I needed to organise some LED lighting modules that I could run from a standard LEGO 7.2-9.0 volt power supply. As I could only source a 12 Volt Modules with which to work with, the project needed some extra electronics to make it work.

NXTCam Lighting System Modified LEGO Parts &  Vehicle Interior Light Modules
24 SMD LED Light Panel & LEGO Connectors

I came across the Car Interior, 24 SMD LED Light Panel, designed for a 12V vehicle system on eBay for $2.80 each including P&P. The Panels will work from a 9  volt source, but fails below about 8.5 volts. Voltage Step-Up ModuleTo get around the low supply voltage offered by LEGO Battery packs, I decided to use a Step-up, DC-to-DC Voltage Converter Module from Sure Electronics to deliver the 12 volts required by the LED lighting modules to work at full specs. This Step-Up Voltage converter is capable of supplying up to 500mA of current at it’s 12 Volt output from a 3-10 Volt input supply. As a single LED Light Panel draws around 150mA, the Step-Up converter is well within specifications for the application.

To make a flexible mount on the LED Module to attach it to LEGO Models, I decided to use a modified Part 32174 Technic, Axle Connector 2 x 3 with Ball Socket, Open Sides. The photograph below shows how the original Part 32174 had the rounded end removed to give a flat surface to glue to the rear of the LED Light Panel. To remove the connector-end with the axle hole  in it, I used a mini cut-off disk on my Dremel Clone utility grinder. This resulted in a flat surface which I scored a couple of grooves to fit over the LED legs and solder pads on the reverse of the LED Module. Simply use some 5 minute Epoxy to attach the connector to the LED Module PCB.

NXTCam Lighting System
Modified LEGO Parts to Suite Light Modules
Modified LEGO Connector Part 32174

Using the modified Part 32174 Technic Connector, allows a connector with a Ball attachment joint to be used, resulting a rigid, but movable connection to your robot. Using a Technic 50923 or 64276, Liftarm 1 x 2 with Ball Joint, is an ideal way to attach these lights.

 

NXTCam Lighting System Modified Vehicle Interior Light Modules
NXTCam Lighting System Modified Vehicle Interior Light Modules
Finished NXTCam Lighting System using Modified Vehicle Interior Light Modules

As can be seen from the two photographs below, these LED Lighting Modules deliver a large amount of light for a very small foot print. They are are painful to look directly at. The light is a very clean white and doesn’t appear to affect the colour of the objects is shone on at all. Both photos where taken late at night in a totally dark room, lit only by the modules. Initially I tried using 4x ultrabright White LEDs, but I couldn’t achieve a flood effect, only managing to produce four overlapping spots, which provide to be in affective.

NXTCam Lighting System Installed
NXTCam Lighting System Modified Vehicle Interior Light Modules in Action
24 SMD LED Light Panel & LEGO Connectors

These lights have reached the goals I set out to achieve easily, by supplying a constant light source which helps to override fluctuations in external lighting levels. Colour changes are effected minimally if at all. When used in my naturally lit lounge room on a cloudy day, such as today, the effects of light level changes due to cloud movements was overcome when using the lights.


LED Light Panel & Voltage Converter Mounted on a LEGO NXT Robot

Yes these Modules are a little power hungry at 150mA, but a light weight 11.1V Lithium Polymer battery will also supply the power requirements for the LED Modules without the need for the Voltage Step-Up Converter for extra running time and at around the same weight as a PowerFunctions Battery Box fitted with 6x AAA Batteries.

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