Electric Ovaloid




Introduction: Electric Ovaloid

About: By day, Jeff is the Jack of All Robots at Clearpath Robotics. By night, a mad scientist / hacker / artist / industrial designer wannabe!

In the future, all the chickens are dead. The Robot Masters felt bad about it, and decided to make it up to us humans by creating a robotic replacement. At least, that's what they said. When pondering the question, "What come first, the chicken or the egg?" their answer was calculated in approximately 2538 clock cycles: The Egg, of course!

This is the result of their work. Or rather, an accurate and authentic replica of the very first robotic egg created by the Robot Masters. Why not post instructions on how to build the real thing? Well, there is a very good reason. When the robotic egg hatches, a robot chicken emerges. Robot chickens are as deadly as rabies-infected grizzly bears* on speed. You see, as usual, the Robot Masters lied to us. The robot chicken was just another effort to wipe us off the planet. You's think they could put all that creative energy to work on something useful, but no. Robot freakin' chickens. *sigh*

Oh! And the worst part? If you do manage to catch and kill a robot chicken, you can't even eat the darned thing! Once you pluck the titanium alloy feathers and remove the fuel cell, the resulting carcass is completely inedible. Worst.pot pies.ever.

So here is an Instructable on how to create the relatively safe (and in a cold robotic way) attractive looking egg replica. It glows pretty colours and responds to sound, just like a real egg!

*grizzly bears are also extinct in the future.

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Step 1: Parts and Tools

OK, so the intro was a little over the top.

I'm not a big fan of bling, but I adore shiny lights. This instructable will tell you how to build an egg-shaped sound-reactive mood light thingy, with all the glitz and glamour of a real Faberge egg. It also has plenty of tiny fiddly painstaking work, also like a real Faberge egg.

What does it do? Quite simply, it's a 48-LED chaser circuit attached to a microphone. When it hears a loud noise (like a clap), a pulse is sent through the chaser circuit. All the while, changing colours illuminate the egg from the inside. This project requires absolutely no programming, but you will need elite ninja soldering skills. The Electric Ovaloid is made up of two basic circuits:

The LED Chaser

Take a look at the schematic for this one. It looks ridiculously easy, and it is! It's simply six inverters strung together in a chain, with an LED at each step. The trick is the resistor and capacitor at each stage. When the leading inverter changes state (high to low, low to high), it passes that along to the next inverter. However, that state is delayed by the need to charge up or discharge the capacitor. The charge time is determined by the RC time constant of the resistor (1.8 megohms) and the capacitor (0.1 uF) - about 0.18 seconds. If the initial state applied to that first inverter stays constant long enough, then the entire chain of LEDs will eventually turn all high or all low. However, by sending a pulse through the chain, we can cause a "wave" equivalent to the length of that pulse to travel through the chain of LEDs!

Note that the Electric Ovaloid uses eight groups of six inverters (each stage uses six inverters in a single 14-pin package) -- but yours can be of any length. Theoretically the chain could be hundreds of inverters long!

The Sound Pulser.

Do you remember The Clapper? That's basically what this is! When the microphone picks up a loud enough sound, it's amplified by the 741 op amp. It's then sent to the 555 timer which is configured as a "one-shot" timer. The inverter at the end formats the pulse for the chaser circuit. The sound, no matter how brief, is stretched out by the timer to a certain minimum value. In this case, it's the time needed to illuminate at least two LEDs in the chaser circuit. The number of illuminated LEDs (the period of the wave) is determined by the RC time constant of R8 and C4. The sound pulser schematic is a modified version of the one I found here.

Want to make yours faster or slower? Just remember that the "speed" the wave travels through the LED chain is determined by the RC time constant - reduce the value of the resistor or the capacitor to increase the speed. The minimum number of illuminated LEDs (the period of the wave) is determined by the RC time constant of the Pulser circuit. Easy enough? Let's get building!

Step 2: Testing

I tested the chaser circuit on a breadboard before building it. This won't be necessary for you to do, unless you want to change the speed of the chaser circuit. If that's the case, then by all means try it out on a breadboard before you build!

If you're experimenting with a different trigger for the Electric Ovaloid (say, a flash of light, a push button, or a pulse from a microcontroller) then try it out on a breadboard first!

Step 3: The Egg

So... where do you get a hollow plastic 6-7 inch high egg, anyway? I lucked out and asked for one on Freecycle. A kind lady a few blocks away had one she was saving from Easter. What she had was pretty much perfect -- the right height, divided through the middle, with an integrated stand. The only problem was the yucky gold paint used for the bottom half. Fortunately, the solution was ready in a handy spray can!

Since noting would really shine through the gold paint already on the bottom half, I decided to paint it gloss black instead. I used Krylon Fusion paint because it plays nice with plastics. Whatever egg and paint you're using, be sure to do a test-spray first. Some paints can melt some plastics, and you don't want your egg reduced to a molten pile of plastic goop!

For top half, I used Rustoleum glass frosting spray. This stuff also played nice with my egg, giving it a nice frosted diffused look, and an eggshell-like finish. I applied three coats do get a sufficient diffusion effect.

With the egg ready to go, it's time for the hard part - soldering!

Step 4: Parts List and Tools

By sheer parts count alone, this chaser circuit is not very efficient. However, its ability to form a nearly infinite chain makes it attractive because there is no central controller. Here's what you'll need to build a single chaser module:

1 x 74AC14 hex Schmitt trigger inverter
6 x 1.8 megohm resistors
2 x 100 ohm resistors (use 50 ohm resistors for white and blue LEDs)
6 x 0.1 uF ceramic capacitors
6 x red LEDs (though you can use whatever colour you want)
26-30 gauge wire
a short piece of 12-14 gauge solid wire (for the "backbone")

The sound pulser uses just a few basic parts

1 x LM741P op amp
1 x 555 timer
1 x 74AC14 hex Schmitt trigger inverter
1 x 100k potentiometer
1 x electret microphone
4 x 10k resistors
2 x 100k resistors
1 x 150k resistor
1 x 1M resistor
4 x 0.1uF ceramic capacitors
1 perf board
2 x slow fade RGB LEDs (optional)
1 x 51 ohm resistor (for the RGB LEDs)

You'll also need a few other parts, including:

a power switch
a USB cable (if yours is going to be USB powered)
a 4xAA battery holder (if yours is going to be battery powered)
hot glue

And here are the tools you'll need:

a soldering iron with a fine point
wire strippers
side cutters
fine point tweezers
hot glue gun
X-acto knife

Step 5: The Chaser Module

I'm not going to lie to you, this part is ridiculously fiddly and I wouldn't recommend it as a first project. The chaser module is built without a circuit board, which means it can be built to any shape - but it's also harder to assemble.

The order in which the inverters are arranged was specifically chosen to make the module as symmetrical and easy to build as possible.

Step 1: Attach the 1.8Mohm resistors to the IC

- bend the leads flat to the body of the resistor, and trim so only a short loop is left.
- slide the resistors onto the leads of the IC. They attach as follows:
- pin 2 to 13
- pin 3 to 12
- pin 4 to 11
- pin 5 to 10
- pin 6 to 9
- pin 1 to free-floating
- Solder all the connections

Step 2: Attach the 0.1uF capacitors

- fold one of the legs up beside the body of the capacitor, and trim so only a short loop remains
- straighten out the other leg
- slide the loop of each capacitor onto the following leads on the IC, in this order:
- pin 1
- pin 13
- pin 3
- pin 11
- pin 5
- pin 9
- solder the connections
- the loose lead of the capacitor connected to pin 9 on the IC should be wrapped around the bundle of other leads twice. Then, wrap it around pin 7 on the IC.
- solder the bundle of leads and pin 7.
- trim the leads so the are all as long as the shortest lead.

Step 3: Attach the 100 ohm resistors

- with one hand, hold one resistor so that the edge of the body is in line with pin 7 on the IC. Take the lead and wrap it around the bundle of capacitor leads. Then, solder it in place.
- hold the other resistor so the edge of its body is in line with pin 14 on the IC. Take this lead and wrap it once around pin 14. Solder it in place making sure to leave enough room to attach other wires later.

Step 4: The light bar

- Start by cutting a piece of insulated 12 or 14 gauge wire, about 1.75 inches long.
- take six LEDs and slide them over the wire, ensuring that the polarity is the same. Bend the LED leads so that the LED stays in place.
- Put a dab of hot glue on either side of each LED so it stays in place
- when the glue is dry, cut each lead so there is about 3mm of exposed (solderable) lead remaining
- cut four short pieces of wire, strip the ends, and solder them between the leads as shown in the picture. Then, flip the light bar over and do the same thing on the other side.

Step 5: Combine the IC and the light bar

- Polarity is very important! Ensure that the side of the LED bar with wires connecting the cathodes (negative pin) is on the same side as the 100ohm resistor that goes to ground (the bundle of capacitor leads)
- Take the loose hanging lead of the 100 ohm resistor and wrap it around the middle LED pin.
- Solder the lead onto the led pin.
- On the other side, do the same thing with the positive-connected LEDs.
- Put a dab of hot glue to connect the bundle of capacitor leads to the light bar

Step 6: Wire up the light bar

- cut six short pieces of wire and strip the ends. Bend loops onto the ends. With the chaser module elevated, hook one wire on each of the remaining LED leads and solder them in place.
- on the other side of the assembly, hook each of the wires onto the appropriate IC lead, as shown. On one side of the IC, the wires will go to pins 2, 4 and 6. On the other side of the assembly, the wires go to pins 8, 10 and 12.
- Solder the wires in place.

Step 7: Inspection and testing:

- Carefully look over the chaser module and check for short circuits and poorly soldered wires. Fix any mistakes.
- When you're sure there are no faults, temporarily attach the capacitor lead bundle to the ground side of a power supply, or to the battery holder. Attach pin 14 on the IC to positive. All of the LEDs should turn on.
- With a wire jumper, temporarily short the unsoldered pin of the first resistor (the one attached to pin 1) to positive. The LEDs should all turn off, one at a time.
- With the same jumper short the resistor to ground. The LEDs should all turn on.

Did it work? Great! Now make more. I made a total of eight before time and patience wore out. Trust me, they get easier to make by the 4th or 5th module...

Step 6: Connect the Modules

Once you have built and tested as many modules as you need, you can connect them together in a chain. The basic idea here is to connect all the grounds together, all the positive supply pins (pin 14 on the IC) together, and the output from one module to the input of the next module.

Line up the modules, and measure wires to span between the connection points. Solder each joint carefully, ensuring a good connection is made. These wires will take a bit of stress when you're gluing the modules in place.

At each stage, test the chain using a power supply or battery pack to make sure the connections are good.

Once all of the modules are connected, solder a single long wire onto the first resistor of the first module. Then, solder wires onto the ground and power pins of the last module in the chain. Note that if you're not packing your modules into an egg, the places where you connect power and ground may be different.

Step 7: Pack the Modules Into the Egg

OK, so there's one more tricky part. Test fit the modules first, to plan out where they will be mounted. When you're satisfied with the positioning, remove the modules and place a dollop of hot glue on the first LED of the first module. Quickly position the module inside the egg and hold it in place until it cools. Work your way around the chain, gluing each module and holding it in place.

Once everything is secure, test the chain again to make sure nothing was disconnected. If not all of the LEDs light up, then you'll have to go in and fix it.... good luck!

Step 8: Build the Sound Pulser

The sound pulser is responsible for sending a pulse to the LED chain when a loud enough sound is heard. It consists of an amplifier, a 555 timer configured for monostable operation, and an inverter. The inverter is needed because the 555 timer outputs a short pulse that goes high, while the LED chain requires a short pulse that goes low.

To build the sound pulser I used a small per board from Radio Shack that I had in my electronics bin. Perf boards are still available, but probably not from Radio Shack. I wouldn't recommend building this part of the circuit without the board, since it's too complex.

Place the ICs down the middle of the board, and place the resistors and capacitors as close to the pins to which they connect as possible. Make sure you leave room for the LEDs, the switch and power connections.

My wiring on this board was rather haphazard, but it works. The first rule? Make sure nothing is shorted together! Once you're confident that everything is connected as it should be, you can go ahead and give it another test-run. When you turn on the switch, the RGB LEDs will turn on and do their thing. The chaser LEDs will randomly light up and start, um, chasing. Eventually they will all turn off. When you tap the microphone or make some other loud noise, a pulse will be sent through the chain.

If this doesn't happen, go back and start trouble shooting.

Step 9: Final Assembly

Phew! The Robot Masters must have build some sort of automated manufacturing robot to do this. But, you're almost done!

You will need to drill three holes into the bottom of the egg (or some other convenient location) Make a hole for the USB cable or power jack, a hole for the switch, and a small hole for the microphone. Of course, if you decided to use an internal battery pack or chose not to install a switch, then you can omit those holes.

Start with the USB cord. In my case, I used a cheap USB extension cable. Cut off the female end of the cable, and strip off about 2" of plastic coating. Inside you'll find a metal ground shield covering four wires. Remove the shield to expose the four wires. Cut off 1.75" of the green and white wires - these are the signal wires and won't be used. Strip a small bit of insulation off the red and black wires.

Feed the cable through the hole until the plug is within inches of the egg, then solder it onto the sound pulser board (don't glue the cord yet). The red wire goes to positive, the black to ground. Then feed the switch into its hole, tighten the nut (if it has one), and glue it in place. Last, put a dab of glue on the edge of the microphone (not in the middle!) and place it in front of its hole.

Draw the USB cord back out of the egg, until only a few inches are inside the egg. You can now put a blob of glue where the cable enters the egg.

With the cable, switch and microphone in place, set the board on top so it's parallel with the base of the egg. Glue it in place at the corners with hot glue.

And now: The Final Step! With great relief and pride, pop the top of the egg on the base. Plug that bad boy in and turn it on! Crank some tunes! See it glow and pulse in response to sound!

Step 10: Fine Tuning and Other Ideas

The potentiometer can be used to adjust the sensitivity of the Egg. You can set it to only respond to the loudest of noises, which will also produce very short "waves." At the other end of its sensitivity range, regular conversation will cause it to trigger.

There are many ways in which you could modify this project. Of course you could build a longer chain of LEDs. You could also build a few separate chains that travel parallel or away from each other, or even snaking about in different directions. The chains could be built into any container or shape. And yes! use different colours for even more effects! The possibilities are endless.

Special thanks to Master Robot 6CV99-K78GG for all its assistance in creating this Instructable. I couldn't have done it without you, '6C!

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    21 Discussions


    Reply 8 years ago on Step 10

    It is currently packed away in a box somewhere. You'd really want to buy it? I expect you would tire of it within minutes.

    Dream Dragon
    Dream Dragon

    9 years ago on Introduction

    If I'm reading this right the speed of the chaser circuit is dictated by the resistance and capacitance in the circuit? So to change the Pace of the Chase you'd need to change ALL the resistors and ALL the capacitors?

    Ok it may not be the most "efficient" circuit of it's type, but it's a very elegant solution and it actually looks good too. I'm not sure I wouldn't want it outside for all to see the beauty of the components...

    Nice work.


    11 years ago on Introduction

    Can you send me the picture of the schematics of the sound switch plz... pm me


    Reply 11 years ago on Introduction

    To view the schematics, download Cadsoft Eagle from www.cadsoft.de. Let me know if you can't do that, and I can send a picture of them.


    Reply 11 years ago on Introduction

    I got the egg on Freecycle. The person I got it from said it was the packaging for an Easter chocolate assortment or something.


    Reply 11 years ago on Introduction

    All those late nights are beginning to feel worthwhile. :)

    Carole B.
    Carole B.

    11 years ago on Introduction

    Congratulations on being a Finalist. I "studied" your design the other night and read your Instructables. It is a fascinating egg; I sent the link to my niece, because I was sure she would be fascinated with it too My Best Wishes to you. Carole B.


    Reply 11 years ago on Introduction

    Thanks! When you break it down the circuit is pretty basic. I only wish I'd had more time to make a longer chain!


    Reply 11 years ago on Introduction

    Thanks! :) It looks even better in real life (as most things do); it was difficult to capture the subtleties of the light patterns on video.


    Reply 11 years ago on Introduction

    I'm sure there's a relation somewhere. Third cousin twice removed or something. ;)


    11 years ago on Introduction

    Awesome, lots of pics and wonderfully documented. I wonder what Seth Green would think......