Clapper LED Candle




About: My hobbies are woodworking, electronics, programming, 3D printing and making sawdust with my CNC Router.

Three years ago I saw "My New Flame" by MORITZ WALDEMEYER, INGO MAURER UND TEAM 2012 at the museum gift shop, and feel in love with the idea. I hoped to recreate something mesmerizing, enjoyable, functional and interesting to watch, but with a slight twist. I certainly couldn't make anything comparable to the their beautiful work of art. Therefore, I created a Clapper version of an LED Candle. Clap twice to turn the candle ON or OFF. The Clapper feature is optional, and can be turned ON or OFF if included in the build. Or, this feature may be omitted from the build entirely.

There are seven of these around my house which I use as ornamental candles and night lights. I keep them plugged into a 5 VDC Cell Phone Charger to power the unit, and to recharge the Li-Ion battery. One charge can last around 18 hours, which makes them great for emergency lighting.

Note: The Candle in the video on the right side with a cover isn't a Clapper Candle.

Step 1: Parts and Tools

Parts Needed for Project:

With Clapper (Optional):


Step 2: Acrylic Base Assembly

Using the PDF Vector drawings supplied, the tool paths for cutting out the acrylic can be created. Each PDF file contains Top, Bottom, two Sides and a small rectangle that is used as a spacer underneath the Sound Module. This part is not needed if you're building the non-Clapper (without Sound) version of this LED Candle.

I used a 1/8" end mill to cut the majority of the parts, and I ran a finishing pass with a 1/16" end mill. The 1/16" end mill is required for the narrow slots on the sides and top.

The mounting holes were manually located and drilled by hand. Some of the holes should be drilled prior to assembly. For example, the holes to mount the PowerBoost board.

Sand and test fit the all the pieces. I recommend using Plast-I-Weld to bond the pieces together.

Note: The diameter of the top and bottom must be sized to the inside diameter (ID) of the resin candle bodies you purchase.

Step 3: Circuitry With and Without Clapper

The basic LED Candle circuitry consist of a battery, switch, power supply and Candle Printed Circuit Board (PCB) with a LED Charlieplexed Matrix, Charlieplexed Matrix Driver and Arduino Pro Mini 5 VDC. An assembled version of the Candle Circuit Board can be seen above. The only connection to this PCB is 5 VDC provided by the power supply. The battery is connected to the PowerBoost power supply, which can charge the Li-Ion battery, and provide protection for a low voltage battery. The power supply also provides a means of switching the Candle ON or OFF by grounding the EN connection via the switch.

The Clapper PCB includes a solid state relay (LCB710) and microcontroller (ATTiny85) to process the signals from the Sound Module and control the power to the Candle PCB. The ATTiny85 is programmed to listen for two loud simultaneous sounds, and toggle the relay ON or OFF. Unfortunately, this configuration cannot distinguish a clap from any other loud sounds, therefore, the circuit will activate if any two loud sounds are heard simultaneously.

I installed a DIP-8 socket on the Clapper PCB to make it easy to install or remove the ATTiny85. All other components can be soldered to the board.

Connect pins 1&2 of J1 for normal operation. Secondly, connect the + & - pins of the Clapper PCB to the + & - of the Candle PCB. Connect the 5V & GND of the PowerBoost power supply to the + & - of "PWR IN" connections of the Clapper PCB. Connect the Mini Toggle Switch SPDT to the "CLAPPER" connection. Connect the pole of the switch to C and the other two connections as desired. Finally, connect the VCC and GND of the Sound Module to the + & - of "SND MOD", and the OUT to the Out connection of the Clapper PCB.

Step 4: Printed Circuit Boards

Attached are the Gerber files I created with KiCad to order the two Printed Circuit Boards. I recently ordered 10 of the Candle Flame PCBs for $5. It so happens, I ordered twice as many boards at half the price of my original 2016 order.

Step 5: Printed Circuit Board Assembly

  1. Install the male headers from the back of the PCB with longest portion protruding out the front. Do not install male header where indicated.
  2. Secure the headers to the back, and flip the board. Solder all header pins on the front side of PCB.
  3. Trim all pins, as indicated in photo, flush to the board.
  4. Orient the Top of the LED Charlieplexed Matrix as seen in photo.
  5. Flip LED Matrix over and install LEDs UP, and solder module to pins.
  6. Solder header to Arduino Pro Mini Board ATMEGA328P 16MHz 5V and solder from bottom of PCB with the longest portion protruding from top of PCB. This will be used later to program the Arduino. After soldering the header, I recommend prying the plastic portion of the header off of the pins. This is because the length of the pins will be trimmed prior to mounting the PCB in the Acrylic Base.
  7. Flip the PCB over to the back and fit the Ardiuno onto the header pins and solder.
  8. Orient and mount the Matrix Driver on the pins at the top of the back and solder.
  9. Attach the USB to UART TTL Module to the header pins of the Arduino. 5 VDC -> VCC, GND -> GND, TX -> RX, RX -> TX.
  10. Connect USB of module to PC and open Arduino IDE to load program.

Step 6: Programs for Arduino Pro Mini and ATTiny85

Adafruit provides a tutorial on the use of the LED CharliePlexed Matrix and Driver at Animated Flame Pendant. I used the same sketch for my Arduino Pro Mini, but change the data.h to a flame of my making. This tutorial provides everything you need to get started with the LED CharliePlexes.

The ATTiny85 uses a sketch I found at Henry's Bench -Arduino Sound Detection Sensor: Tutorial and User Manual. This page will guide you through the configuration and tuning of the Sound Sensor Module and Arduino. My sketch (ClapperCandle_V2.ino) for the ATTiny is almost identical to his example.

Step 7: Final Assembly

Once the PCBs have been assembled, they can now be installed on the acrylic base. As mentioned before, the drilling of holes is recommended prior to gluing. If you are building the Clapper version, the rectangular spacer piece cut out earlier is located on the side of the Sound Module mounting location. This can be seen in the photo above. The Clapper PCB is mounted below the Sound Module and on the same side.

Wire the PowerBoost 500 power supply to the battery and main power switch, and if the Clapper PCB isn't used wire the 5 VDC and GND directly to the "PWR IN" connection of the Candle PCB. Otherwise, wire the output voltage of the power supply to the + & - of the Clapper PCB. Wire the SPDT toggle switch to the "CLAPPER" connections as instructed previously, and connect the Sound Module to the "SND MOD" as instructed earlier. The respective connections (+ - TRG) of the Clapper PCB are connected to the Candle PCB. The TRG connection is not connected to anything.

Check your wiring against the schematics, and when you're ready install the battery and turn it ON.

The resin Candle requires a hole for the micro USB cable to connect to the power supply. Therefore, I mounted these on my CNC and cut a hole the correct distance from the bottom.


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    14 Discussions


    Question 3 months ago

    Hello I just finished mine today on the pcb from your files and uploaded your sketch and it works great but the flame is upside down! Everything is mounted right to your instruction. so not sure whats wrong. Any way to invert graphics? thanks

    2 answers

    Answer 3 months ago

    Thank you it took about four times doing that and it finally worked Thanks again great project.


    Answer 3 months ago

    Download my data.h file, and replace Adafruit's file with mine. Recompile the sketch, and the flame should be right side up.

    Orion Maker

    4 months ago

    Love it! Good Job!


    Answer 4 months ago

    I originally used, and had great success and fast service. Recently, they charged me $5 for 10 PCBs plus shipping. You might try they have 10 pcb for $2 plus shipping. Pricing is very competitive these days.


    4 months ago

    This is one of the more interesting and unique projects I've seen. Very realistic!

    1 reply

    Question 4 months ago

    hi, nice project, nice ans expensive, i read some part of the above project, i did not find many about the material used for the case, i mean the white cylinder. could you please describe it. and one suggestion, display candles in a dark room if your camera supports it

    2 answers

    Answer 4 months ago

    There's a link in the Parts list to Lumiere Candles Inc.. These cylinders are made of a resin plastic with a matte finish. The look and feel of these are very much like real candles. It can worked like cast acrylic plastic, and I found it easy to mill on my CNC. Yes, several of these parts are expensive, especially the 6" H x 3" OD cylinder.
    I don't have a video of it in a dark room, but the amount of light generated by the LED Candle is comparable to real candle of the same size. The small LED's on the power supply are noticeable through the cylinder in a dark room.


    Reply 4 months ago

    thank you for response, here is my candle project which i created before Christmas. it just used attiny13 and coded in assembly, it was planed to be my first project on Instructable website but i just hanged in trouble for creating a well formed candle cover, i selected many materials consist of resin epoxy. but no success in building it by self. i think a real candle can be sloted to be used as cover.


    Reply 4 months ago

    Nice design and more like "My New Flame".

    Alex Kov

    4 months ago

    You might be interested to replace the 'clap' feature with the 'blow out' feature. Imagine 2 contacts made of copper foil that are placed inside the candle's body face to a hole. You blow into the hole, the contacts close, which provokes a 'reset' impulse, then the contacts return to their initial position because of elasticity. The candle goes OFF, you'll have to turn it ON again with the switch.