Introduction: Glowing Air-Bubble Clock; Powered by ESP8266

“glowing air-bubble clock” displays the time and some graphics by illuminated air-bubbles in glycerin. Unlike led matrix display, slooowly drifting, glowing air-bubbles give me something to relax.

In early 90’s, I imagined "bubble display”. Unfortunately, the idea was not realized at that time due to my limited skill and time, and similar idea products made by others until now. Now, the right time has come to me to realize my “glowing air-bubble clock”. Starting with some basic and preliminary tests, “glowing air-bubble clock” has displayed the time on my desk, at last.

This bubble clock is version 2 for me. Version1 uses water as liquid and it may be inferior to version2 in display quality, but the unique movement of the bubbles in this version 1 is fascinating to me.

I would appreciate it if you could tell me in the comments section what you like best about either this version2 (glycelin) or version1 (water).

Step 1: Parts, Materials and Tools

I want to make “glowing air-bubble clock” as minimal as possible using common parts. Some solenoid valves were tested and cheapest also smallest one bought from AliExpress was selected, but I have not confirmed its durability. Based on such preliminary test results, basic dimension is designed that font: 8 bits width, display area: roughly 200mm height x 90mm width.

I bought the proper-size transparent-glass vase, and designed acrylic parts based on the vase and other air handling parts.

1. air handling parts ( purchased parts information at the time I bought, just for reference)

  • solenoid valve: 8pcs
    (AliExpress, 1.79USD/pc, named "DC 5V 6V Electric Mini Micro Solenoid Valve Air Gas Release Exhaust Discouraged 2 Position 3 Way For Gas Air Pump") *1
    *1 (2020-5-7); normal-close 2-way solenoid valve(open when power ON) is better for this usage.
  • air branch pipe; eight outlets with valves
    (, 1556JPY, named "Uxcell Aquarium Air Tube Bifurcation Elbow/8 One-Way Exit Lever Pump")
  • air pump
    Select a proper air pump at your own responsibility. Close all valves for a long time that may cause overheat of the air pump.
  • tubing; ID6-OD8mm, ID4-OD7mm, ID3-OD6mm
  • tube joint; L-shaped , I-shaped
  • acrylic board; transparent; thickness 2mm and 3mm
  • acrylic board; black; thickness 2mm

2. circuit board parts

  • ESP8266
  • OLED display; 0.91” 128x32
  • I/O expander IC; MC23017
  • LED strips; NeoPixel: 8pcs
  • FET; 2SK2412: 8pcs
  • Diode; IN4002: 8pcs
  • AC adapter; 6V-1.8A
  • misc. parts

3. misc.

  • glass vase; OD120mm Height260mm
  • glycerin; purity 99%, 2.5L
  • box casing
  • adhesive

4. tools & etc

  • laser cutter to cut acrylic boards
  • misc. tools to assemble electric circuit board
  • accessible WiFi

Step 2: Cutting Acrylic Parts by Laser Cutter

Using laser cutter, acrylic parts are cut.
Just for your reference, ai ( adobe illustrator ) file *1 is attached. They are designed for the glass vase and other air handling parts which I bought. The glass vase size: inner size 113mm dia, 243 height, outer size 120mm dia, 260mm height.

*1 (2020-3-20); ai file is revised not to overlap each layer drawings. I have tried to upload the same contents saved as .dxf file, but not correctly uploaded, suppose to be something system bug in

*2 (2020-3-27); thickness and color of acrylic board information are added to the caption on the picture above. Click the picture to see the captions.

Step 3: ​Assembling Air-handling Parts

L-shaped transparent tube-joints are used as nozzles, tightened on transparent acrylic part. Acrylic parts are put together. Separaters between each nozzles prevent mutual interference between neighboring bubbles.

nozzles, solenoid valves, air branch pipe and air pump are connected by proper size tubing.

*1 (2020-5-7); on the fifth picture, the not-in-use outlet (open when power OFF) of 3-way-solenoid-valve is sealed. normal-close 2-way solenoid valve (only outlet open when power ON) is better for this usage.

Step 4: ​Assembling Control Circuit

Just for your reference, my design note of circuit diagram is attached, may be hard to read. Some parts are selected in my hand so that not optimized. Photos of assembled control circuit on front and back side are added, not-well-done wiring but if it may be of some help for you.

WiFi connected ESP8266 controls eight solenoid valves via I/O expander; I2C Interface, so that to display correct time on air bubbles also on the OLED display.

Eight NeoPixels are set in line glued on acrylic part (named "NeoPixel support-top") to be located under each air nozzles using "NeoPixel support-side" and "NeoPixel support-top spacer" to illuminate air-bubbles. They are installed in the box casing.

Step 5: Assembling Totally

air handling unit, circuit board and others are assembled totally.

Then, pour glycerin in the vase. The glycerin I bought is purity 99%, 2.0L.

Step 6: Arduino Coding

For your reference, arduino code is referred to here.

Please refer to other article regarding to ESP8266 arduino coding and OTA uploading. Sorry for not-smart code and Japanese comments.

Your wifi_ssid and wifi_password need to be input in line:
wifiMulti.addAP("your_wifi_ssid", "your_wifi_password");

Step 7: Tuning and Confirm

Tuning is important for making bubble character shape a better read.

1. tune 8 manual valves to reduce variation of air bubble volumes from each nozzle, rising speed of bubble depends on its volume.

2. On arduino code; main OTA, following parameters define the air bubble volume and vetical gap between air bubbles, set them properly. Depending on the temperature of liquid and air hadling unit specs, these parameters are need to be modified.
・int bubbleDelay = 15; // delay time in m sec to keep solenoid valves open, define the air bubble volume
・int bubbleSeparateDealy = 1000; // delay time in m sec to define the vertical gap beteen air bubbles

    You can modify/add font data on the arduino code what you want to display on your “glowing air-bubble clock”.

    Close all valves for a long time that may cause overheat of the air pump. Confirm the air pump whether continuous operation is available or not at your responsibilty. Also, the durablity of solenoid valve shall be confirmed. It may be critical on your usage.

    Thank you for your interest to my project. Have a nice relaxation time with this clock!

    Please check on the Make It Glow Contest, below entry, too.

    Make it Glow Contest

    Grand Prize in the
    Make it Glow Contest