A-level project

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  • I've known Gordon for years, its about time I got one of my students to do a successful project with espruino!

    So here it is, he's a great student, who should have just used 25leds.

    1x espruino, 50 smd LEDs, 50 tiny little jars, 50 lengths of 4core wire.

    The wooden bit is effectively the ceiling rose, and they will all hang down at various lengths.

    Will update this later. He is having problems with the LEDs seemingly hitting different colours than the data sent..

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  • Really a cool, creative invention!... I like it... looking forward to see movie of this light contraption in the dark.

  • Those are WS2812B's?

    They don't use RGB color order - could that be the color issue?

  • I'll find out what type they are today hopefully. The issue he has is when sending the data, say 255, 0, 0, some LEDs will be red, but then it appears to 'overflow' and some will be other colours. The good news is after about 8 hours of soldering all the LEDs light, just the software to sort now.

  • Thanks for posting the picture - I love the little spirals of wire for power :)

    I'd love to see some pictures when it's on!

    The flickering could be a power supply issue... Is it just being powered from USB at the moment?

    I'd maybe add some capacitors (at least 47uF) across the power lines, at the beginning and end of the spiral.

    Also if you're powering the LEDs directly off a 5v supply there's sometimes the issue of voltage levels for the data signal that make it a bit glitchy. You could try adding a 300 Ohm (ish) resistor between the data wire (B15?) and the 5v for the LEDs, then add the line:


    That'll make the output so it only pulls down to 0v, and then the resistor will pull up to 5v. It means you end up with a full 5v signal (which should be more reliable) rather than the 3.3v you'd usually get.

  • There is about 0.5 amps of mobile phone charger powering it.

    They are rings of power, in parallel.

    Will pass on the comment about the power supply!

  • ...that's a bit meagre... each LED - red OR green OR blue - consumes about 20 mA when running on 255 (with intensity 255). So when all shining white with 255 255 255 (with intensity 255), that's all colors - red AND green AND blue - on, a single 'bulb' consumes 60 mA. With 500 mA you can ran about 8..9 'bulbs' at one time and then the power supply tanks. There are USB power supplies out there that can deliver more than just 500 mA. Furthermore, I do not know what exact kind of LEDs you are using and also what the software is looking like, in other words how you drive the LEDs: continuously or with pulses. For the naked eye fast pulsed LEDs look like continuously on, and this way you can seemingly have more than above number of LEDs shining white, but with an overall less brightness delivered. To be of better help, you have to provide a bit more technical details, most importantly what LEDs are used and how they are powered physically and over time.

  • @allObjects I have a bit of background on this - I think the lights are something like the attached image.

    WS2812s internally do PWM, but as you say, at full brightness it's going to be drawing WAY more than the phone charger can provide. If you do use a more powerful charger the Espruino itself has a self-resetting 1A fuse, so that'll hit you after a bit too.

    For the moment, your student could use small numbers (and some capacitors) - like try driving with 31,31,31. He could still max out a few of them if he wanted though (just not all of them!).

    I guess the other thing is if it's a 0.5A power supply, it might be quite a cheap one? Could be it generates a lot of noise on the 5V line (or maybe even substantially more than 5V) and that's throwing the lights off a bit. Sticking capacitors on would help, and he could also try putting a diode between Espruino's Bat output and the Lights' voltage input. It's drop the voltage by 0.7v, which would reduce the current consumption and might also lower the voltage, making the signal to the lights more reliable.

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  • Also, the photo is a bit blurry so I can't see where power and GND are wired on?

  • http://youtu.be/Jb63tcccPqA

    Woohoo. A 1A psu and a resistor to pull b15 up did the trick!

  • ...now it's time to cork the 'gazillion' bottles(jars) - and un-cork (at least one different) one to celebrate! - Congratulations!

  • Looks awesome - can't wait to see the final thing :)

    Not sure if he's seen it, but on this page it's got one or two other patterns, and a way to change between them using a button.

  • That looks awesome. What's going to go in the bottles?
    Some things I've seen (or used):
    Clear beads, crystals, or marbles - these reflect the light around in interesting patterns.
    Cotton gauze/fluff (like the stuff cotton balls are made of) - the cheapest LED diffusers ever :-P
    Plastic film, folded, crumpled, or catch the light in interesting ways.
    Flourescent material - the red/orange flourescents will glow under most blue LEDs, but not under the green and red. You might be able to get glow in the dark stuff to glow too under the blue.

  • I Think he is going to fill them all with resin, interesting points about diffusing the light though. He should probably trial it out.... Would look good in his folder!!

  • Resin makes it quite 'final'... no fixing, just chopping of... I could think of (ver) small clear glass beads... because of the whole in them and their shape, they will disperse the light in all directions... If you are afraid that the jar will fall off because the cork drying out, you still can use some glue... just make sure there is enough glue to create an interlocking bead inside / wider than the opening.... beads make though only sense when the jars are small ~:(

  • Finality is what he's after, but the beads sound cool.

  • Fist Sign of testing with the Jars....

  • That looks amazing!

    Please let us know if you want some help with different light patterns :)

  • Interesting layout: The spiral and the blob at the bottom!

  • Very nice!
    ps: I like the black wires

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A-level project

Posted by Avatar for JGreen @JGreen