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My obsession of this year is full-color LED. I have made Aurora 9x18 as a result. As much as I love the scale of Aurora 9x18, I also wanted to have something smaller, perhaps something that can go on a costume.

Here's Aurora mini 18. It has 18 full-color/RGB LEDs on a smallest possible circle. With a single PIC microcontroller, changing 18 RGB LEDs smoothly is reaching the technical limit. With the new PIC with wider supply voltage, the circuit is simplified compared to Aurora 9 bar, and use of two AA or AAA batteries (3V operation) or one Lithium battery is now possible.

Step 1: Concept & Circuit


Like Aurora 9 bar, Aurora mini 18 borrows its circuit from Aurora 9x18. Operating principle is exactly the same. Just extended the hardware and software to control more LEDs.

One of the new 24F line of PIC microcontrollers is PIC24FV16KA302. Unlike the similar PIC24F series controllers which are 3.3V limited, this controller can operate fully up to 5V. This eliminated the need for the 3.3V voltage regulator, and simplified the LED driving circuits. The resulted circuit with fewer parts count made this Aurora to be very compact.

Step 2: PCB & Parts


Aurora mini 18 uses surface-mount technology (SMT). If you've never built anything with SMT, this might be a good opportunity to try out. You will most likely realize that there's nothing to fear about SMT. (If you are not familiar with soldering, you might get your feet wet with something simpler than this though.)

The high-quality, custom made PCBs as well as the full kits are available at a reasonable price. Please view the details at "For Sale" section of the forums.


Parts

Here is the list of parts. All except LEDs are available at Digi-Key (digikey.com).
  • 1x 10k Ohm (0603)
  • 3x 220 Ohm (0603)
  • 3x 2.2k Ohm (0603)
  • 18x 150 Ohm (0603)
  • 2x 0.1uF (0603)
  • 2x 10uF (1206)
  • 3x Q1x: MMBT2907A
  • 1x PIC24FV16KA302 (SS)
  • 18x Tricolor LED (common-cathode) (SparkFun COM-09264 should be identical) http://www.sparkfun.com/products/9264
  • 1x Tactile Switch
  • 1x 3 - 5V power supply: regulated AC adaptor, 4 NiMH, 2 AA/AAA batteries & case, single cell Lithium battery, or USB cable
  • 1x 2 pin Molex header (right-angle recommended) (optional)
  • 1x 2 pin Molex connector with corresponding terminals (optional)

There are many places to purchase LEDs. I source LEDs directly from China via AliExpress. Takes a few weeks for delivery, but the prices are great. (If you are purchasing a lot of LEDs.)

You can substitute transistors if you have something compatible.

Step 3: Tools & Supply

  • Tweezers
  • Soldering iron
  • Solder (flux core. go for the highest quality solder you can afford.)
  • Soldering flux (Use high quality flux. Low quality flux causes problems! ChipQuick brand recommended.)
  • Wire cutter (I recommend this one.)
  • http://www.amazon.com/Xuron-170-II-Micro-Shear-Flush-Cutter/dp/B000IBSFAI
  • Microchip PIC programmer (supports PIC24FV16KA302 and capable of In-circuit programming through a standard 6-pin ICSP connector, such as PICKit 3, ICD 2, ICD 3.) (PICKit 2 does not support PIC24FV16KA302.)
  • Computer running Windows or Mac OS
  • Magnifier visor or other visual aid device (optional, but highly recommended)

Step 4: Notes on SMT


If you are already familiar with SMT, you can skip this step.

There's no need to use reflow method (solder paste & bake) to build Aurora mini 18. Since there are only a few components to solder, it's quicker to just hand solder everything.

It's very helpful to use high quality flux when you solder SMT components. I'd say it's the key to successful hand soldering of SMD. Apply a small amount of flux to the PCB pads before placing the device, then solder. If you haven't done this before, you'll feel like your solder skill has suddenly improved :)

Step 5: Assembly


Please download and print the "Parts Placement Chart". Use this to identify/guide where all the parts go.

I recommend following the order listed. Also be mindful of electrostatic charge. Use anti-static desk mat if you have one. Or place aluminum foil under the PCB like I do.

Washing the Board
Solder everything _but_ the switch. Then wash the PCB with water. I've had many problems of LED flickering a while after the assembly due to the slight short circuit caused by flux residue. Even with high quality flux, solder joints can accumulate dust, and with moisture in the air creates electrical conduct. The problems went away after I started washing my PCBs.

Wash PCB in warm water and detergent. Use old toothbrush to scrub the solder joints, making sure all of the flux is off. Rinse very well with warm water, and dry completely using a hair dryer. (Very important)

If you solder the switch by mistake, please don't wash the board. Switches can not be wet. Instead, use cotton swabs and alcohol or flux cleaner to clean the flux residue.

After the PCB is cleaned and dry, solder the switch, and assembly is finished!

Step 6: Choose Power Supply Connection


The power supply voltage needs to be between 3 to 5V DC. If you are using a wall wart, make sure it's regulated. (Most of 5V wall warts are regulated type, but if you are unsure, measure the output voltage. Unregulated wall warts output much higher than 5V without a load.)

The supply can be as low as 3V (with a decreased LED brightness of course), so you can use variety of batteries; two Alkaline batteries, one Lithium cell, three or four NiMH batteries, etc.

Square pad on the PCB is negative, and round pad is positive. Be very careful not to apply voltage in reverse polarity! It will most likely destroy the unit - can't tell - I never tested.

Another cool thing is to use USB power. Aurora mini 18 draws less than 150 mA, so most (if not all) USB ports should work.

Step 7: Electronic Check & Program the PIC


Check carefully for bad solder joints and parts placements errors. Before moving on further, take out your multi-tester and check the Ohm reading of the power connector and ICP connector pads. Make sure there are no shorts.


Then fire up your PC, launch Microchip IDE. If you don't have it, please download it from Microchip website. Scroll down to the bottom of the page to find the downloads. (http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en019469)

Here are the steps for the IDE ver.8.xx:
  1. Select programmer - click on "Programmer -> Select Programmer" choose your programmer here. (Note: PICKit 2 doen't support PIC24FV family)
  2. Select device - click on "Configure -> Select Device" and choose PIC24FV16KA302 under "Device" menu.
  3. Import HEX file - click on "File -> Import", and open the HEX file downloaded.
  4. Click on "Programmer -> Settings", and click on "Power" tab. Then turn on "Power target circuit from PICKit 3", and set the voltage to 5V. (Note: this setting may not be available with some programmers. If that's the case, connect power source to the Aurora.)
  5. Click on "Programmer -> Reconnect". Click "OK" if you get the "Voltage Caution". You should see some messages in the "Output" window. Check connections, etc. if you get errors. 
  6. Programm the PIC - Make sure to insert the header pins into the ICSP holes of the Aurora and hold it securely. Click on "Programmer -> Program" to start the programming. It should only take 20 seconds or so, and you will see "Programming/Verify complete" message in the "Output" window.
That's it!

I used PICkit 3, but other programmers such as ICD2, ICD3 should work. (PICKit 2 doesn't work with PIC24FV16KA302)

Just use those 5 holes/pads on the PCB as though they are the female connector. Give a bit of tension sideways to make sure the electrical connection is stable.

*** Firmware update is available - download at http://www.theledart.com/blog/archives/1012 ***

Step 8: Enjoy!


I hope you enjoy the beautiful and hypnotic color patterns as much as I do. I have a few well tweaked patterns in current firmware to chose from. A push of the switch changes the pattern. Hold down the switch for two seconds turns the lights off.

<p>Hello,</p><p>Would be possible to get source code, because I have a lot of at tinys and megas at home and would like to use them, before ordering PIC (and I don't have PIC programmer :( ).</p>
<p>Hey i built it and everything works great except that there is no red. Any idea what could be the problem?</p>
<p>The LED leads are very close together and easily shorted by solder. The shorts are not always easy to see, but cleaning the soldered PCB with alcohol (or PCB cleaner) helps examin the soldering visually.</p>
<p>Hey, is there a way, you can send me gerber and drill files, so I can make PCB on my own?</p>
I would like to use something like this to do one of those lightup christmas trees in my ard but i would need to connect a string of lights where each of those leds would be. is this possible? also can i program it to flash on and off at a certain time so i can make it flash to music?
Connecting more LEDs to Aurora mini 18 is not very straightforward. Of course it's probably not impossible, but I leave that as a challenge for you to solve...<br> As for music sync, check out <a href="http://www.theledart.com/blog/archives/1516" rel="nofollow">Aurora 12 bar with Audio Interface</a>.<br> <br> Aki
Cool!
Cool!
there is a girl in my class named aurora that iv`e had a crush on , now i know what to give her. <br>
Cool! Was she also &quot;mini&quot;? :)<br>
LOL a little bit
I just finish incorporating the mini 18 into an infinity mirror. It looks great if I do say so myself.
Does look great! Congrats! <br> <br>Aki
I would like to know more about the technique you are using to handle the PWM. Is the source code available for this project ?
Email me at aki (at) theledart (dot) com and I will email it to you.
Just finished building mine from your kit. That's really cool. Makes me a lot more interested in the 18x18. That's the fifth kit of yours I've assembled. I continue to be pleased with the quality of design, construction and function of all your kits. Thanks and keep up the good work.
Thank you so much for your support!<br> Hearing people&nbsp;successfully&nbsp;building my projects makes me really happy.<br> <br> Aki
Hi!<br>Just completed it and programmed it, but it just do red and purple, what could be wrong? mostly red...
First, check to see if there are no shorts between LED leads. Use a multitester set in Ohm (k Ohm) range and check the resistance between them. If it's very low like 0-10 ohm, you have a solder bridge somewhere.<br> <br> Also check to see the Q1G (transistor in the center). It's easy to have loose connection on the transistor leads. You can apply a small amount of flux on the leads and give a little heat from a soldering iron.<br> <br> Lastly, you should check the soldering of the PIC. Pin #21 drives the green channel, so pay extra&nbsp;attention&nbsp;to this pin. Again you can apply flux, and give a little heat on the lead to make sure there's a good bond.<br> <br> Hope you found the problem.<br> <br> Aki
Aurora mini 18 kits are now back in stock! Thank you for waiting!<br> <br> https://www.instructables.com/community/Aurora-mini-18-Kit-and-PCB/<br> <br>
what website do you go to for the kit?
Here's the info:<br> &nbsp; <a href="https://www.instructables.com/community/Aurora-mini-18-Kit-and-PCB/" rel="nofollow">https://www.instructables.com/community/Aurora-mini-18-Kit-and-PCB/</a><br> <br> It's out of stock right now, but will be available by February.<br> <br> Thanks!
can you use other LEDs too?<br>and whats the diameter of the pcb?
I'll rephrase: is it possible to mount single color LEDs on it, like for example green ones, while at the same time keeping the animation program the same.
You can. You can insert ordinary single-color LED into the PCB, only using two of the four holes. This will connect the LED to the blue circuit, leaving red and green open. So you will get the blue-only animation in the color of your choice.<br> Note that the placement of the LED will be a bit off if you do this...<br>
Not sure what other types of LEDs can fit...<br> The diameter of the PCB is 50mm.<br> <br> Aki
This is such an awesome lighting effect! I am working on a project having to make lighting effects with an Arduino board. Is it possible to control the Aurora 18 mini with an Arduino board?? If so how would I accomplish this? <br>
I guess one can use SPI or something to communicate between Aurora and Arduino. I will look into it for the next firmware upgrade.<br> <br> What sort of things you want to control from Arduino?<br> <br> Aki<br>
I had wanted to control the Aurora sequencing of colors with the Arduino. I didn't know how the PIC worked and was wondering if I could use an Arduino to replace this as the controller. I guess I would need to look into the SPI. The other parts of the project are controlling a string of LEDs with an Arduino. I would need to know if it would be a possibility by this next week for presentations. I had just found this lighting effect and thought it would be an awesome thing to add!
To control Aurora with Arduino (or any other digital devices) Aurora has to be able to take commands. I have to correct what I said in that SPI is not possible because it uses at least two I/O lines, where Aurora 18 only has one I/O pins available as external I/O (one that connects to the switch).<br> You can still use this pin to receive data using async serial.<br> As for replacing the PIC with Arduino, I guess that's possible, but not an easy task. PIC24F used here is a bit more capable than Arduino...<br> <br> Hope this makes sense...<br> <br> Aki
Really nice design. I'd love to buy a kit but am worried I will probably ruin it with my soldering skills. <br><br>Would you consider selling a kit with the surface mount suff pre-soldered?<br>
mr nick - send me your kit and I'll assemble it for you - no charge. These go together in about 30 minutes. I have built (2) of the Aurora 9x18s, a 9 bar and the Mini 18. If you are intersted, drop me a PM or email - rclay701 at gmail dot com.
It's very beautiful!
PCB layout? eagle files?
That would be neat to put on a bicycle for riding at night.
looks cool, Is it possible to show a photo of the back?
Here - for now... I will upload a better picture later.<br>
Do want. Do want do want do want.<br><br><br>Any chance you might be selling a kit for this?
<br> Yes! Just posted the <a href="https://www.instructables.com/community/Aurora-mini-18-Kit-and-PCB/">details</a> in the forum.<br>
It says Aurora 9x18 being assembled...hmmm...<br><br>
Reused the pic from Aurora 9x18 instructable...
Do you have the Source code? for editing?<br><br>I am trying out the Aurora bar code you uploaded...FUN STUFF!
Very nice. <br><br>In the video how was the pan out and blurry to clear performed? Was it done in post or was it all smooth camera work?
Simple and stunning. It's quite hypnotic!
This is art.... truly beautiful

About This Instructable

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Bio: I am an electronic artist living in Brooklyn, NY. I work with LEDs and microcontrollers to create beautiful objects.
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