The Light Clock (IoT)





Introduction: The Light Clock (IoT)

Welcome to The Light Clock, part art-piece, part timepiece, it's a modern take on the classic analogue clock. Where a traditional clock face uses hands to tell the time, The Light Clock turns your whole wall into a timepiece through a striking display of coloured light. You have the power to choose from millions of colours, allowing you to perfectly complement your existing décor, or simply to match your mood.

NEW!! We're offering pre-orders of "The Light Clock Kit" Which contains all the electronics and LEDs required to build the light clock with no breadboard or soldering. Make the body, add power and you're done!

We've also just had a successful kickstarter campaign and if you don't want to build your own you can now pre-order the clock here!

Step 1: How to Tell the Time on the Light Clock?

To create the hour and minute hands, The Light Clock projects light in two different colours. At first glance this might seem complicated, but very quickly you’ll notice that you can read it with ease.

In this example we’ve used yellow light as the hour hand, and blue light as the minute hand. Comparing each Light Clock with the corresponding traditional displays, you can see how each colour comes to an edge where a hand would normally be. Click for an animated example.

Step 2: Parts and Tools

What you need is a

· Power Drill

Bigger tools required (shapeways is a good alternative if you don’t have these tools)

· 3D printer

· Laser cutter

Parts required:

· NodeMCU-12E

· Breadboard

· Jumper leads

· 144strip of Neopixel LEDs

· 3.3v to 5v logic level converter

· 5V 4A power supply (LEDs use looooots of power)

Step 3: Build the Breadboard

To get started we will build the board. We need to link the

NodeMCU12E to the NeoPixels, but because the pixels are 5V and the NodeMCU12E is 3.3v output on its pins, we will require a logic level converter. We need to connect 3.3v and GND to the logic level converter on one side, and 5V and GND to the logic level converter on the other side. Afterwards we can take an output from pin D2, put it on an input to the logic level converter and to the Neopixel input line.

We need to add a 1000uF 6.3V+ capacitor to the 5V power so that the inrush current won’t damage the NeoPixels. This isn’t crucial, but don’t come crying to me if you blow up your pixel strip if you didn’t have them :P

Wire 3 should be unplugged for now. We will plug it in later when we want to power the board off our DC jack instead of USB.

Step 4: Installing the Board to Arduino IDE

For this part you’ll need the Arduino 1.6.5 IDE (or higher).

The IDE for the ESP8266 is pretty new, so you’ll probably
need to install it. Open up File->Preferences and, under “additional boards manager”, simply add

Now hit OK and go to “Tools->Board->Board Manager” and
select “type: contributed”, after which the ESP8266 board should show up.

Hit “Install” and go make a cup of coffee, this can take quite
some time. :)

Step 5: Uploading the Code

Once the board is installed you should be able to select the

correct board under Tools-> Board: NodeMCU 1.0 (ESP-12E Module). Of course, if you’ve bought a different version of the board, then select that particular one from the list.

You don’t program the ESP8266 like a normal Arduino chip. You’re actually over-writing the entire firmware on the chip. To do this you have to put it into boot loader mode.

Plug the board in, so that you should see the little blue LED light up. Then, hold down the “flash button” and briefly press the “Reset” button while still holding flash. This will put the unit in bootloader mode so you can then upload your code to it, which you can find on GitHub.

I have made a couple of modifications to some of the libraries which you can find here and here

Disclaimer: due to the fact that I’m am engineer in my everyday job, not a programmer, the code might miss a thing or two. If you notice anything which can be improved, please link back to me and let me know. :)

So, in order to upload it, unzip the file and open it in Arduino. Note: make sure you hit the right arrow, as the screenshot shows:

If the code doesn’t upload properly, go ahead and check whether all the required libraries are installed. There are quite a few of them! If you need help installing them, you can find it here.

Step 6: Give It a Shape

OK, so you have a long strand of LEDS connected to a

micro-processor. It might be pretty, but it sure isn’t a clock yet! For that you’ll have to build a body.

I’ve uploaded a 3D print to thingiverse which you can download. You may have to cut it into several sections in order to print, in case you’re using a smaller 3D printer.

Print this off. You have a little notch for the LEDs to poke through - put the wires here and make sure that you wind the LEDs around the clock CLOCKWISE, otherwise you’ll have to learn how to tell time backwards! :P

NeoPixels should come with backing tape, but if not, a bit of hot glue or bluetac can be used to keep them in place.

Mount our breadboard on the top of the donut like in the photo (which is from a different prototype, but it should do).

Step 7: Add the Face

To add the face to the clock you will need a laser cut acrylic sheet and an "attractive" face. I use anodized metal, but you could use more acrylic, cardboard, canvas, wood. Whatever you like :)

Cut a 300mm disc of acrylic, cut a 182mm circle out of the center, then drill a 5mm hole out of the center of that.

Glue the 182mm circle to the 3d part we printed earlier (the design in the photos is a square, sorry I have a lot of different prototypes)

Place the 300mm disc around the cutout section.

Bolt the "attractive" face (should be 260mm with 5mm hole in it) to the part to hold the whole thing together. I use "Chicago Post Screws" you can find them on ebay.

Step 8: Add Power

Screw in your DC jack into the hole in the centre and plug the wires into the breadboard on the 5V side:

Step 9: Testing, Testing!

All you have to do now is to boot up the unit and test it. Make sure it’s plugged into the computer to the 5V power. Open up Arduino and click on the COM Port (highlighted yellow in the first image).

You should get a stream of data as the clock boots up with the default settings (second image).

The settings assume that you are in Australia, but don’t worry we can
change that.

Step 10: Connecting to Your WiFi

Now we have to set up the clock to be able to connect to your wifi network. You’ll need your phone for this.

First connect to “The Light Clock” wifi network. Because this network isn’t connected to the internet phones can sometimes take a little bit to do this. Just stick with it, you’ll get connected.

Then open your internet browser (Safari, Chrome, Firefox) and type “” into the address bar (where you’d normally type

Select the wifi network you want your clock to connect to, type the password associated and hit “Submit”. Don’t get scared if the screen displayed is not exactly the same as the one shown in the picture above, functionalities are still the same.

Next, you’ll be taken to the time-zone menu, similar to the screenshot below. You can set your time-zone for anywhere in the world and the clock will keep perfect network time.

Whoo-hoo! High-five for a fully functional light clock built by yourself! Now just bear with me for a little longer, this is where we get to the fun part!

Step 11: Customising the Colours

The whole colour spectrum is at your disposal, you just have

to make your pic! The light clock can display millions of colours, so you can customize it to fit any décor. Here’s how.

Special step for PC: To find the clock on your network, we use a service called mDNS. This works natively on all Apple products (Macs, iPhones, iPads), but you need to install a little helper if you use a PC. Once this is installed you can move to the next step: finding your light clock.

Open your browser and type in thelightclock.local/ (make sure you DON’T type www first and make sure you DO type the “/” at the end).

You will now end up in the main menu, where you can change
the colours by clicking on the hour or minute colour. Hitting the “Update the light clock” button will make your clock on the wall apply the new colour scheme you just chose.

Step 12: Other Settings

If you hit the "Settings" button down the bottom you'll find a host of other things you can play with. Would you like a seconds hand? Should the clock dim itself at night? Would you like little markings to help you tell where there hours are? All of this and more are customisable in the settings menu

Step 13: You're Done!

Thanks for reading and watching :) If you like this clock and want to support us on Kickstarter that would be awesome. If you built your own and want to let me know how it went that would be awesome too!

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116 Discussions


Question 24 days ago


Awesome work, i enjoy this clock for almost 2 years.
I have a problem and im not sure if is hardware or software, my clock use to stuck from time to time (3 times in 2 years), it lose the connection to wifi, i can see it with my phone, but if i try to remake the wifi setup it will reboot and is not connecting to wifi and i cant see it anymore on phone, the only solution is to flash it again. Any ideea?
Best regard,


Question 6 weeks ago

Thanks for any help. I am having a problem compiling this sketch. Arduino 1.8.5 / NodeMCU 1.0

After collecting all necessary libraries I get this fatal error

Arduino: 1.8.5 (Mac OS X), Board: "NodeMCU 1.0 (ESP-12E Module), 80 MHz, 4M (1M SPIFFS), v2 Lower Memory, Disabled, None, Only Sketch, 115200"

In file included from /Users/Zerah/Documents/Arduino/libraries/NTP/ntp.cpp:13:0:

/Users/Zerah/Documents/Arduino/libraries/NTP/ntp.h:38:25: error: 'SECS_PER_HOUR' was not declared in this scope

time_t _syncInterval = SECS_PER_HOUR;


/Users/Zerah/Documents/Arduino/libraries/NTP/ntp.cpp: In member function 'time_t NTP::getNtpTime()':

/Users/Zerah/Documents/Arduino/libraries/NTP/ntp.cpp:54:53: error: 'SECS_PER_HOUR' was not declared in this scope

return secsSince1970 + (time_t)(totalOffset * SECS_PER_HOUR) ;


exit status 1

Error compiling for board NodeMCU 1.0 (ESP-12E Module).

I am including the chrismelba NTP library. Any help would be appreciated


1 more answer

Hey man, somewhere you have to define SEC_PER_HOUR as 3600. Just do it at the top of the sketch and I think you should be ok :)

Thanks for this ! It's Awesome.
I have a compilation error. I don't understand :-/
My setup : Arduino 1.6.13, Board used : esp8266 V 2.4.0

In file included from /Users/stephanegueulette/Documents/Arduino/libraries/NTP-master/ntp.cpp:13:0:

/Users/stephanegueulette/Documents/Arduino/libraries/NTP-master/ntp.h:38:25: error: 'SECS_PER_HOUR' was not declared in this scope

time_t _syncInterval = SECS_PER_HOUR;


/Users/stephanegueulette/Documents/Arduino/libraries/NTP-master/ntp.cpp: In member function 'time_t NTP::getNtpTime()':

/Users/stephanegueulette/Documents/Arduino/libraries/NTP-master/ntp.cpp:54:53: error: 'SECS_PER_HOUR' was not declared in this scope

return secsSince1970 + (time_t)(totalOffset * SECS_PER_HOUR) ;


exit status 1

Do you have an idea please ?
Thanks a lot.


1 reply

Try using this library for NTP

This is beautiful! I love the idea to use ambient light to show the time, very creative. :)

Hi Chris,

I loved this idea and was about at it for couple of days. Done with the connections and the code. Its working just as you intended it to. Just the clock face is pending.

I was wondering if we can make this code work with the Blynk app. Or else just add the code for rainbow/glitter/confetti patterns. To show off to the friends ;).


Salil G

1 reply

The code is all open source so you can add anything you want! If you do, please make a pull request so that I can add it to the main code-base :)


1 year ago

Hi Sir! Amazing project! But really need your help. Your midday start from the first pixel. But my clock have some wires. I want to move midday to the middle of the strip. So Then my wires will be down.


hi there,

first of all, great job, great project.

i just wanted to build my second one, but i ran in some problems

i use an 60dots led strip, which is working correctly.

as it only has 60 led´s i changed that from 120 to 60 in the code and reupload it.

but now, only every second led is flashing for the seconds

after 30 seconds the second pixel dissapears and appears again after 30 secs

so i think, the code is still calculating with 120 pixels

did you ever ran into sth like this ?




1 year ago

Really wish there was a way to use standard RGB strips with "R, G, B, PWR" inputs haha. Can't afford the expensive neopixel strips :(


1 year ago

that is possible if we use power boost so this clock can use some battery ?

1 reply

You can try. The clock draws about 10W at full brightness, though as low as 2 or 3 on lower brightness settings. You could get a big battery and give it a shot.

Not sure I understand what the 3.3v to 5v logic level converter is doing as it works fine without it, or is it just strictly used if your running of usb power?

3 replies

Hmm, it's meant to be in there if you're powering the LED strip from 5v power, as in theory the signal should be the same voltage as the power source. If you're powering the LEDs off 3.3v, or if it's just working anyways, then I guess it's not needed! I've never tried without using it to be honest.

from the diagram I cant tell it looks like you have 5 volts going into it and 3volts from the MCU on the other side, not sure what it does really at that point. I thought at first it was supplying the the 5 volts to the leds if you where running of strickly usb.

Yeah, it takes a 3.3v signal and converts it to a 5v signal for the ws2812bs to read. At least that's the theory

This is a Great project. I have been looking at the Neopixels and this would be a great way to start with something practical for my wife's sake.

I downloaded you code and after I removed the two Websocket includes I got an error on the NTPh reference. Can you indicate what library you used. There are lots of libraries out there and it would be best for me to use the same one you used in this build.

In fact, it might be best to include either references to all your libraries.

Thanks in advance for your help

This one is to connect to the arduino i have the Freeduino Uno. i Don´t know the wire that is for data in the neopixels

Hello i have a 120strip of neopixel and instead of the NodeMCU12E i have ESP8266 Wifi 3.3v logic level. can you help my in some way ? im making a project to finish my high school and if i dind finish this I will lose all my 3 years of school. sorry to bother