Introduction: EL Wire Neon Nixie Style Clock

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This Instructable describes how to make a clock using EL wire. The design of this clock resembles a combination of a Neon sign and a Nixie clock.

While creating a "Neon" name board with EL Wire, I wanted to add some animation. This resulted in some arduino controlled EL wires. And somehow I came up with the idea to create a clock using EL wire.
This clock contains a total of 40 EL wires, of which 32 are controlled by an Arduino. And all time between 00:00 and 23:59 can be displayed with these EL wires.

This instructable starts with making a simple name board with EL wire. Then a single EL wire is divided into several wires. And these are controlled with an Arduino.
Then the design and the build of the clock is described. Together with two different build options for the electronics: A solderless version with relays and a version with triacs.

With 21 steps this instructable has become more extensive than necessary for this clock. But the additional steps provide extra information to get started with EL wire. And that does not necessarily have to be this clock.

Step 1: Electroluminescent Wire

This project uses electroluminescent wire (EL wire). This is bendable and looks like a thin neon tube, which makes it ideal for flexible decoration. And it gives 360 degrees of visible light at the whole length.

El wire consists of a thin copper wire coated with phosphor, with two thin wires wrapped around it. The phosphor acts as an isolator/capacitor and starts to glow by means of an alternating current. This happens at a voltage of about 200 Volt, with a frequency of 1000 Hz. However, the required voltage does not have enough power/energy to be dangerous.

El wire is available in different lengths and different colors. For this clock I use orange EL wire. And I've ordered 8 pieces of 4 meter at Gearbest (about $3,55 a piece). This gives over 100 feet (32 meter) of orange EL wire. And most of it has been used for this clock.

EL wire has some disadvantages: It doesn't give as much light as LEDs. And the color might fade from sun exposure. Since this clock is used in a shady environment, I will not be bothered by this.

Step 2: EL Wire Name Sign

Making a name sign with EL wire is easy. It doesn't require any soldering or working with electronics.

Start with a rough sketch, on paper or on a large cutting mat (first image). The black taped parts will be on the backside of the wooden panel.

Copy this design onto a piece of wood. And drill 2.5 mm holes in the wood to thread the EL wire through. Cut the cover cap of the EL wire, and start (from the back side) with the first letter.

Although EL wire is easy to glue, I've used a different technique. Drill a very small hole (0.8 mm) and use a thin copper or fishing wire to attach the EL wire (third image).

Step 3: Arduino Controlled EL Wire

In this step we are going to control the EL Wire through an Arduino.

EL wire acts different than a light bulb or LED. The rapid charging and discharging of the phosphor emits light. The wire can be modelled as a capacitor with about 5nF of capacitance per meter. And EL wire has a high resistance of 600 KOhm per meter.

The inverter uses 2 AA batteries to convert the DC to a high voltage AC output. The inverter combines the capacitive EL wire with a transformer (spool) to create high voltages. Each change in voltage on the primary side of the transformer creates a voltage on the secondary side. With a sinus wave, the height of this voltage depends of the turns ratio of the transformer.
But this inverter applies voltage first and then turns it off, giving a square input wave. Now the magnetic flux inside the windings produce a flyback voltage. And this voltage can be much more than the applied voltage. Without an EL wire attached, the output voltage can be very high. Even up to 600 Volt. This can damage the internal electronics of the inverter: Always connect some EL wire to the inverter before turning this on.

The inverter has a switch. And the EL wire turns on when the button is pressed. By pressing the switch permanently, the wire will immediately glow when the batteries are inserted (or power is connected). This makes it possible to control the supplied voltage (3 Volt) with an Arduino. But this will require an inverter for each EL wire.

Switching the (high voltage) AC with an Arduino requires a Triac. Triacs are electronic component that conducts current in either direction when triggered. They work almost the same as transistors, but then for AC current. I'm using BT131 triacs which can handle up to 600 Volts for this instructable.

The triac is directly controlled by an Arduino. The circuit in this step has no additional (optical) insulation between the low-voltage and high-voltage parts (don't use this circuit for switching AC mains voltage).

Step 4: Flashing Name Sign

This step uses 5 EL wires and an Arduino to create a flashing name sign. It uses triacs to control the EL wires. And one EL wire should always be on (the inverter requires a minimum load). Therefore power on the Arduino first, and then the inverter.

The electronic circuit is placed on a breadboard and controlled by an Arduino. The Arduino is powered by a power bank, and the EL wire is powered by 2 AA batteries.

void setup() {
    pinMode(0, OUTPUT);
    pinMode(1, OUTPUT);
    pinMode(2, OUTPUT);
    pinMode(3, OUTPUT);
    pinMode(4, OUTPUT);
}

void loop() {
    digitalWrite(0, 1);
    digitalWrite(4, 0);
    delay (500);

    digitalWrite(1, 1);
    digitalWrite(0, 0);
    delay (500);

    digitalWrite(2, 1);
    digitalWrite(1, 0);
    delay (500);

    digitalWrite(3, 1);
    digitalWrite(2, 0);
    delay (500);

    digitalWrite(4, 1);
    digitalWrite(3, 0);
    delay (500);
}

Further in this Instructable I will describe how this name plate can be made, even without soldering.

Step 5: First Design

There are different ways to make a clock with EL wire. And I've chosen to take advantage of the continuous 360 degrees of visible light which is emitted. And I use the same technique as Nixie tubes: All numbers are placed one behind the other.

Because EL wire gives less light, and isn't translucent, the letters can't be put straight behind each other. As a result all figures must be shifted slightly relative to each other.

For this first design I started with LEGO and an old computer/UTP cable. This gave some insight into the (im)posibilities for this clock. For example, the number of layers and crossings must be minimized. This resulted in the following adjustments in the figures:

0 - the top and bottom circle don't have to be the same size.
1 - placed slightly to the left.
2
3 - turning point underneath other figures.
4 - placed slightly to the right, horizontal line slightly down from the centre.
5
6 - no semi-circle for the upper part , use a line.
7 -
8 - upper round can be smaller than lower circle.
9 - no semi-circle for the lower part, use a line.

Only the following digits are required for the full display of a clock:

most left digit: 0 1 2
middle left digit: 0 1 2 3 4 5 6 7 8 9
middle right digit: 0 1 2 3 4 5
most right digit: 0 1 2 3 4 5 6 7 8 9

This allows for all valid values between 00:00 and 23:59. I have chosen to make four equal pieces, ever unit can display all 10 digits.

Step 6: Fusion 360 Design

All figures are drawn in Fusion 360 after building the prototype. The distance between the lines is 4 mm, with a thickness of 2.3 mm for the EL wire.

EL wire isn't electrically conductive, so the wires may touch each other. I've choosen to get as many parts of the numbers as possible in the top layer. There are some interruptions by other lines, but the main characteristics of a number will remain visible.

Not all figures require the same amount of EL wire. However, shorter EL wire emits more light than longer EL wire.Therefore the final (used) lengths of the EL wires differs from the minimum required length.

The measured required minimum lengths are:

0 - 50 cm
1 - 30 cm
2 - 45 cm
3 - 45 cm
4 - 45 cm
5 - 50 cm
6 - 45 cm
7 - 40 cm
8 - 65 cm
9 - 45 cm

Attachments

Step 7: 3D Print

The design of the figures is about 5 x 10 inch (13 x 25 cm). It's printed in two parts because it is too big for my printer. This model requires little infill, and has been printed at a 0.2 mm layer height. Still each part takes about 5 hours to print (UP plus 2 printer).

Remove all support material after printing, and make sure the EL wire fits through the holes. Use a 2.35 mm or 2.4 mm drill to open these holes. This is best done with a small hand drill. Rotate the drill slowly while holding the drill head. Don't use a dremel to open these holes.

Attachments

Step 8: EL Wires

This clock requires 40 EL wires of about 50 to 70 cm. The required lenght depends of the figure, but there shouldn't be too much difference in lenght. Otherwise, the number 1 will be brighter than number 8.

It's easy to shorten EL wire. But reusing the remaining parts is a little tricky. First, the outer (orange colored) coating must be removed (about 1 inch/ 3 cm). Next, remove the clear protective sleeve, without breaking the thin corona wires. Heating the protective sleeve makes this more easy. Never place the EL wire inside a flame, this will burn the phosphor.
Scrape some off the phosphor off the copper core. Remember that this is also the isolator between the corona wires and the copper core.

Now wrap some copper tape over the protective sleeve. I've used copper tape for making circuits on dolls houses (from a local hobby store). But any thin copper tape can be used.
Wrap the copper tape twice around the protective sleeve. And place the corona wires over the copper tape, and wind the tape once over these wires. Fold the corona wires towards the end of the EL wire, and cut them at length. Place the assembly in a clamp, and solder a wire to the corona wires and the copper tape. Insulate this part with some heat shrink tube.

Solder another wire to the core. And insulate this with heat shrink tube. Finally, test the soldered EL wire.

I've made 42 wires with different lengths:

30x - between 55 and 60 cm
8x - between 60 and 70 cm
4x - between 70 and 80 cm

There is a great article about soldering to EL wire on the Adafruit website.

Occasionally the thin wire touches the middle wire after cutting EL wire. This creates a short circuit. Cutting again fixes this problem most of the times.

Step 9: Switch 40 Wires

The number of I/O ports of an Arduino are limited. And this clock requires 40 output ports. This requires a circuit to increase the number of I/O ports

There are different integrated circuits with which this is possible. And one of them is the 74HC595N shift register. This IC gives 8 output ports with only 3 input ports. And the IC's can be chained, because they are controlled by synchronous serial communication.

This clock requires 5 shift registers for 40 output ports. With each output port attached to a resistor and a triac. All unused port of the 74HC595N are connected (gnd or 5V) to prevent floating input ports. Therefore no additional pull up or pull down resistors are required.

I've made a Tinkercad circuit to test the first version of the Arduino code. This code uses arrays to convert the time to the required bits for the shift registers. The operation of the program can best be explained by means of an example. This example uses the time 19:30:

1 = most left number (display 4)
9     
3 
0 = most right number (display 1)

There are 4 arrays, one for each digit. The first step takes the bytes that belong to the number of that digit:

1 = {0x00, 0x00, 0x00, 0x80, 0x00}
9 = {0x00, 0x00, 0x00, 0x20, 0x00}
3 = {0x00, 0x20, 0x00, 0x00, 0x00}
0 = {0x01, 0x00, 0x00, 0x00, 0x00}

Adding these hexadecimal numbers (0x80 + 0x20 = 0xA0) gives 5 bytes:

0x01, 0x20, 0x00, 0xA0, 0x00

These are sent to the shift registers (from left to right). This gives the following data send to the shift registers. And each bit correponents with a number of that display:

byte    =    0    0      A    0      0    0      2    0      0    1
bits    = 0000 0000   1010 0000   0000 0000   0010 0000   0000 0001

number  = 9876 5432   1098 7654   3210 9876   5432 1098   7654 3210
display = 4444 4444   4433 3333   3333 2222   2222 2211   1111 1111

The most right bit is attached to the 0 of the most right display. And all enabled bits give the value '1930'.

Attachments

Step 10: Clock Back Plate

The 3D printed parts are placed on a piece of medium-density fibreboard (75 x 35 cm, 29.5 x 13.7 inch). Drill 40 holes (2.5 mm) using the PDF document. Print this file at 100% (A4, use 'actual size' in Adobe Reader), otherwise the holes are at the wrong places.
I've covered the back plate with wallpaper. This has almost the same color as the 3D printed parts (silver).

All electronics and (excess) EL wire is hidden at the rear of this plate.

Attachments

Step 11: Clock Assembly

Glue the 3D printed parts onto the back plate. Use some small pieces of EL wire to align the holes.
Pull the EL wire through the holes and start forming the numbers. Always start at the lowest opening. For example, number 1 comes under all other figures. I started from the top to the bottom and didn't use any glue.

Pull the end of each figure through the corresponding hole. And don't cut off the remaining EL wire.

Step 12: EL Wire Test

Test all wires before tightening and fastening. A faulty wire can now easily be changed. And if you didn't label the EL wires: this is the moment to label them. This makes the assembly a lot easier.

I've attached two alligator clips to an EL wire inverter to speed up testing 40 wires.

Step 13: Connectors

This is not my first Instructable. And most of my Instructables end with possible improvements. And even with this Instructable not everything went as expected.

I've ordered some connectors to simplify the assembly of this clock. These wires are normally used to connect Lipo batteries. And I wanted to use them to connect the EL wires to the prototype board. But the ordered JST connectors didn't have a 2.5 mm spacing/pitch. As a result I can't use these connectors/wires.

Fortunately, I also bought some other connectors for the power supplies. And I've used some remaining connectors for the 10 digits on the outer right. The other wires are directly soldered onto the prototype board. Here I've split the (AC) wires . One AC wire goes, from each EL wire, to the prototype board. The other AC wire is directly connected to the AC power supply (inverter). This saves about 40 soldering points.

My advice is to use (2.5 mm) JST connectors (or dupont wires) for all connections to the (protoype) board.

Step 14: Electronics

The electronics for this clock can be divided into multiple parts:

  1. Arduino
  2. EL Wire inverter
  3. EL wires
  4. Power supply

The Arduino and shift registers are powered by an 5 Volt power supply. I've modified an USB cable to power the Arduino. It's possible to connect the power supply directly onto the +5 and GND pins. But the USB connection doesn't bypass the Arduino's power regulator and protection.

The EL wire controller is a combination of the "Arduino Controlled EL Wire" and "Switch 40 Wires" steps. All 40 LEDs are replaced by BT131 triacs. These triacs have the following specifications:

  • Non Repetitive -State Current: 13.7 A
  • Rated Repetitive Off-State Voltage VDRM: 600 V
  • Off-State Leakage Current @ VDRM IDRM: 0.1 mA
  • State Voltage: 1.5 V
  • Holding Current Ih Max: 10 mA
  • Gate Trigger Voltage - Vgt: 1.5 V
  • Gate Trigger Current - Igt: 7 mA
  • Mounting Style: Through Hole Package / Case: TO-92-3

Two values are required to calculate the value of the resistor: Gate Trigger Voltage and Gate Trigger Current. These values, combined with the 74HC595 output voltage of 5 Volt, leaves 3.5 Volt (5 - 1.5) for the resistor. And 3.5 volt divided by 7 mA gives a restor of 500 Ohm.

The recommend current of the 74HC595 is 6mA per output. This requres a (3.5 V / 6 mA) 583 Ohm resistor. Since this clock only uses (maximal) two outputs ports at the same time, both currents are save.
These are minimum values for the resistors. I've used 1 KOhm resistors for my prototype board. Keep the value for these resistors between 580 and 1000 Ohm.

The resistor is connected to the triac's middle pin (gate). One of the two other triac's pins is connected to the common ground (GND) and the other pin is connected to the EL wire.

I've made 41 EL wires. And 40 are used for the figures. The remaining EL wire is used as "minimum load" for the inverter. This wire is placed out of sight.

The EL wire used for this Instructable requires 2 AA batteries. The specified voltage for the inverters is between 3.6 and 4.5 volt. The Arduino requires 5 Volt and van be powered by an Ikea Koppla USB charger or a regular 5 Volt power supply.

Although the inverter is not made for 5 Volt, I connect it directly to the power supply. Should the invertert break, I still have 6 left. And then it's time to order a 5 Volt USB inverter. An additional advantage is that the EL wires give slightly more light.
Another option is to use a (low) resistor. This isn't the most efficient solution, but the EL wires use little current.

The inverter makes a small 'humming' sound (about 1000 Hz). This can be reduced by packaging the inverter. I've both tried glue and epoxy. This reduces the sound to an acceptable level.
Do not place the inverter directly on the wooden plate. Bacause this will amplify the sound.

All parts are soldered onto a large HD638 prototype board (8.5 x 20cm). The image shows the component side!

Al 40 EL wires are soldered onto the prototype board. It is possible to solder the wires directly on the board, but it is more convenient to use connectors.

The image shows the component side of the prototype board and the copper lines shouldn't be visible on this side. The AC power (EL wire inverter) is connected to the common ground and to the two lines near the the red AC mark.

The most right digit (number 1) is connected to the most right shift register. Start with the numbers 0, 2, 4, 6 and 8. The last wire (8) is connected to a different shift register than the first 4 wires. Then solder the numbers 1, 2, 3, 5 and 9. Repeat this for the other digits.

Solder EL wire number 41 straight to the board (red AC and ground). This is the minimum load for the inverter.

Now it's time for a final test, before connecting the Arduino. First remove all shift registers. Then connect the 5 Volt and the AC power sources.

For each IC socket: Connect pin 14 (Vcc) to pin 7 (Qh). This will trigger the connected triac, and the digit '0' will light up. Repeat this for all other Q-pins (6, 5, 4, 3, 2, 1 and 15).
This will test all 40 triacs and EL wire connections.

Step 15: Arduino + 74HC595N + Triac + 40 EL Wires = FAIL!

I've tested most individual parts of this clock before I started. And I thought this design should work:

  • The EL wire can be controlled by an Arduino. And I've tested this with multiple EL wires.
  • Two shift registers have been tested with 16 LEDs. And I've simulated 40 LEDs in a Tinkercad circuit.

I also tested the assembly in several steps:

  • Soldering 42 EL wires (used 40 + 1).
  • All triacs, without shift registers. All EL wires are off. The corresponding EL wire lights up when one of the ports is connected to the 5 Volt power supply.
  • The shift registers have been tested with an Arduino and 16 LEDs.

But after connecting an Arduino I did not get the expected result: I couldn't control all wires. I could turn them on, but some didn't switch off.

First I placed a capacitor between 5 volts and the ground, to reduce voltage peaks. But this didn't solve the problems.
Because I managed to control the EL wires with an Arduino my first thought was to increase the number ports, without the shift registers. For example with an Arduino Mega 2560.

But after some more tests it looks like my simple schematic (with only one triac) doesn't always work like it should. I've managed to control multiple El wires with an Arduino. But there is no guaranty that this circuit works with many EL wires. It's more "trial and error" with many variables. And even the length of the EL wire is a variable.


Step 16: Relays

It looks like triacs might work (somehow) for this clock. The only problem is that they don't work 100% like they should. May be they are only designed to switch a sinus-wave AC current. But not the square/spiky AC current of the EL wires.

The problems might be caused by the capacitive behaviour of EL wire. As a result, the voltage and the current are not in phase: There is still voltage across the triac when the current is zero. This might be the reason why they don't switch off. And explains my suspicion that the length of the EL wire is one of the variables.

That's why I switch to "plan B": Relays. These can switch up to 230 Volt (AC).
The invertor can produce higher voltages without any load. But the actual voltage with EL wire attached is about 200 Volt. And the inverter does not provide enough power to burn the contacts at higher voltages.

Another advantage of a relais is the separation of the Arduino and the EL wire circuits. In contrast to the previous circuit: this circuit can switch mains voltage.

As I proceed with relays, I continue to work on the triac version.

Step 17: Solderless EL Wire

This step describes how to shorten the EL wire without soldering. This solderless connection might look less strong or permanent. But the twisted wires and copper tape make a solid connection. And it gives the same result as the soldered connections.

This EL wire connections combined with relays boards (and an Arduino Mega board) doesn't require any soldering for this project. It's not the cheapest solution: An Arduino mega board and relays are more expensive than an Uno board, shift registers and triacs. But not that much more expensive. With a better chance of succes, for those who have little experience at soldering.

Remove the outer coating and clear protective sleeve (heating helps). Wrap che copper tape 2 times around the protective sleeve and place the thin corona wires over the copper tape. Wrap the copper tape once over the thin wires. Twist a wire around the two corona wires and wrap the remaining copper tape around these twisted wires. Don't forget to place some shrink tube.

Scrape some off the phosphor off the copper core. Twist the second wire around the core and use some copper tape to improve/secure the connection. Insulate all parts with shrink tube. Finally add some tape and test the EL wire.

Step 18: "Solderless" Name Sign

This names sign contains 5 EL wires. It requires an Arduino and 4 relais. I've used an 8 relay module, but only used 4.

Each relais/switch has one input and two outputs: "on" and "off". When the relais is off, the AC power (red line) is passed to the next relais. The fourth relais has an EL wire connected to each output.
When all relais are "off", the power is transfered to EL wire "e" (there is always one EL wire on). Switching on a relais, gives power to the corresponding letter. But this blocks power for other EL wires. To control the EL wires separately, each wire must have its own relay.

These relays switches on when the port value is LOW, and are off when the port is HIGH. This is the opposite as the triac's.

The Arduino code is almost the same as the first name sign example. The only difference is the HIGH (1) for on, and LOW (0) for off. Use ports 0,1,2 and 3 as output ports. Leave output port number 4 unused.

I've made an Tinkercad circuit with 8 relays. Where all light bulbs can be switched separately.

Step 19: EL Wire Clock With Relay

Switching to relays has another advantage. The electronic part of this clock is a lot easier to make (like the name sign). The relais are attached to an Arduino by breadboard wires. And the relays have screws to connect the EL wires.

There are Arduino modules with 8 and 16 relays. This clock has 40 EL wires for all figures and requires a minimum of 29 relais: 13 for the two digits on the left (00-23) and 16 for the digits on the right (00-59):

  • most left digit: 0 1 2
  • middle left digit: 0 1 2 3 4 5 6 7 8 9
  • middle right digit: 0 1 2 3 4 5
  • most right digit: 0 1 2 3 4 5 6 7 8 9

Each pair of figures requires 2 x 8 relais. Both the left pair and the right pair can display the numbers 00 to 59.

The Arduino can be used to power the relais. Only a maximum of 4 relays should be on at the same time.

I've used an Arduino Mega for the relay version of this clock. It's also possible to use An Arduino Uno with shift registers. Replace the resistors and LEDs by the relais in the tinkercad circuit:

Each relais switches a single EL wire. Pin 0 switches the most right 0 and pin 1 switches the most right 1. All four digits require 32 pins. And I've skipped the pins for the unused EL wires: Pin 16-19 aren't used.

Attachments

Step 20: Triacs V2

I started this Instructable with Arduino/triac controlled EL wires. This design did work (somehow) for a few EL wires, but failed with 40 wires. And I solved this 'problem' by usage of relays.

There are "ready to use" sequencers for EL wires. Most of them can control 8 EL wires, and some of them even contain a microcontroller. This clock would require 4 of these sequencers which must communicate with each other, making them hard to use for this project.

The SparksFun EL sequencer is about $35. It's great for EL wire projects, but too expensive for this clock. So I didn't gave this product much attention, until I switched to the relays version. The SparkFun sequencer is released under the "creative commons attribution share-alike license". And all documentation is available at their website. Including the electronic diagram with triacs!

I've ordered some triac drivers and triacs at Farnell. And tested the SparkFun circuit on a breadboard with my first EL wire project. And the SparksFun schedule works fine.

A working schedule means that it is possible to control this clock with triacs. I didn't order enough triac drivers for the entire clock. But I've managed to control two digits with triacs (13 EL wires, 00-24). At this moment my clock is using both triacs and relays.

Step 21: EL Wire Clock

After 3D printing the frames, soldering almost 40 EL wires, and connecting all wires this clock is almost finished. The last step is to add a frame to hide all (EL) wires and electronics. I've used silver (spray) painted wood for this frame. Cover the entire back of the clock with non-translucent material. This hides the light from the 41th EL wire (minimum inverter load).

The final result is a large EL wire clock with some "neon" and "nixie clock" elements.

This clock can be made with triacs and/or relays, with or without shift register. And the list of required materials depends of these choices:

Electronics for the relays version:

Electronics for the triac version with shift registers:

The relay version will be slightly more expensive. But it is easier to make.

It's recommended to add an RTC clock. To keep your Arduino in sync with the actual time. My next step is to replace the last relays with triacs. And to replace the Arduino with a Wemos D1 Mini (ESP-8266). This connects this clock to a NTP server.

Although not everything went immediately as expected, I finally succeeded to create this clock. Nevertheless, I have decided to include the "design error" in this Instructable. Together with two different solutions for this problem.
Therefore this Instructable may not look like a regular Instructable. But it gives all information to create this clock. And more important: It contains plenty of information for anyone who wants to make something with EL wire.

GosseAdema

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