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Mr.RC-Cam

Bubble Blowing Bear: The Story of My Pandemic Panda

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Late February 2020, when the COVID-19 pandemic shizz was beginning to hit the fan, I noticed more families spending time outdoors. The sidewalks are usually empty around here, but slowly my quiet neighborhood began to come to life.

Soon hoards of walking/biking moms, dads, and their kids began traveling by. This unusual migration of neighbors was a side effect of the Coronavirus lockdown.

For fun, many nearby homeowners put teddy bears in their windows to entertain these nomadic visitors. It's a game; count the most stuffed bears and you're the winner. The windowed teddy bears are not a new thing, but the pandemic seems to have increased their popularity.

The teddy bear hunting game seemed brilliant to me. So I wanted to join in on the fun; Especially since a distraction from the Coronavirus pandemic had to be a good thing.

I didn't have a stuffed toy bear to display. So a window was decorated with a big panda bear drawing. Soon families were pointing at it during their walks. Below is a graphic of the two foot tall bear that was printed.

bear_dwg3_300.jpg

 

By early March 2020 the pandemic worries were escalating and I wanted our bear to add a bit more joy to the world. That's when I decided our teddy would blow bubbles and talk to the visitors.

So I'm here to tell the story of my pandemic panda. We call him Bubbles-the-Bear. He is WiFi enabled, has a friendly child-like voice, and makes a lot of bubbles using a homemade soap solution. Stick around, I'll be showing photos of the build and will include some commentary.

 


YouTube Videos
Best if watched using 1080P Quality setting


 

 

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The Bear and his bubble machine are built into a 45-inch high wooden frame that's fitted into an upstairs window. There's some 3D printed hardware that holds it in place. Setting it up in the window is an effortless installation.

BearInWindow1_600.jpg

 

WindowParts1_800.jpg

 

Down at street level there are two arcade gaming buttons that send a radio signal to trigger the Bear into action. The bright red button on the tray is large enough for elbow presses. A second electrically tethered button is for foot activation (hands-free for Covid protection). It does not matter which button is used, they both wake-up the bear.

button_tray1_800.jpg

 

There's a big wooden power pole on our lawn that is a convenient place to install a banner sign and the two buttons. Should the power company discover it I expect a stern lecture about hanging stuff on their ugly utility pole. And if the bear fails to charm them I'm prepared to dig a hole and install my own post.

Printed instructions invite the visitor to press a button if they want to play. Most tap the lower button with their foot and occasionally some use their elbow to press the upper tray button. We thoroughly disinfect the tray area several times a day.

ButtonPole1_600.jpg

 

The two buttons are wired to a 433MHz Remote Control transmitter purchased from a Chinese supplier. It has a four channel encoder, but only one button channel is used.

RemoteFob1_600.jpg

The circuit board was removed from the plastic FOB case and reinstalled in a 3D printed housing. The original 12V battery was changed to a common 9V type. Range is about 150 feet which is more than enough.

 

Tray_Inside_View1_800.jpg

The button activated transmitter is mounted inside the tray unit. I discovered that the RF amp stage had good impedance matching to a compact helical antenna I borrowed from another 433MHz project. That is to say, range was better than the factory whip antenna.

 

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Making bubbles is a simple task that is just a bit of soap and air. Or so I thought.

It turns out that bubble blowing success is affected by several variables: For example, the contour of the wand, air management, and the soap solution's formula all contribute to the bubble maker's performance.

There are twelve wands that are arranged in a carousel configuration. It's just a slow rotating wheel.

BubbleMachine1_800.jpg

 

All the parts are 3D printed in ABS plastic. Bright garish colors are ideal for this kind of project.

BubbleWand1_600.jpg

 

The bubble making mechanism uses a low RPM Gear Motor and a mini Squirrel Cage Blower. They were purchased from a China supplier and delivery took a couple months.

motor_fan2_800.jpg

 

Both are 12V rated devices, but run at lower voltages that are configured during "calibration." A custom web app is used to adjust the gear motor and blower speeds. Specifically, PWM (pulse width modulation) control is used to alter their supply voltages. This calibration step is important to ensure good bubble production.

Here's a screen shot of the web app. The settings are stored in FLASH memory for use as power-up defaults. Yes, this little fellow is smarter than the average bear.

webApp1_600.jpg

There's a float switch in the soap reservoir for monitoring the fluid level. Status is sent by eMail and MQTT messages (for home automation alerts).

FloatSwitch1_600.jpg

 

Here's an example of an email message that is sent with each playtime interaction.

EmailMsg1_500.jpg

The bubble maker can be removed from the window frame for refilling or cleaning. Just unplug a connector and lift it out from the frame's lower trap door. Here's a rear view, which shows the electrical cable for the blower, wand motor, and float switch:

BubbleMachine2_800.jpg

BTW, the reservoir holds an entire day's worth of soap fluid. But as mentioned, if the level gets too low I'm sent an email to refill it. I prefer an email over text, but either notification method is possible.

 

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Let's step back for a moment and talk about bubble production. Normally a person blows into a soap dipped wand while observing the bubble form. Air volume / lip position is adjusted in real-time to create the perfect bubble. A classic closed loop system.

My bubble maker runs open loop. Even so, it does a remarkably good job at blowing bubbles. As mentioned, the blower and wand speed are programmable, which helps out a lot. Admittedly, some success is probably a bit of magic and luck.

The very first test used a 12V drone battery to run the blower and a 2.4V NiMH battery for the wand carousel. I set it up outside and let it run for awhile.


The results were promising. This ad-hoc testing confirmed that a calibration step would be needed for optimizing the blown bubbles. At this point the hardware/software to do that was still under construction.

I also experimented with the bubble solution mixture. There's plenty of recipes published on the interwebs. Typically the magic ingredient is corn syrup or glycerin. So far I'm having good luck with Palmolive dish soap (original formula), food grade gylcerin, and filtered water. I make about a half gallon at a time. After mixing I let it rest overnight to help degass it.

SoapMix1_800.jpg

 

 

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Let's not forget that the Panda Bear is an important part of the entertainment. It's no secrete that most kids (and adults) like teddy bears.

The bear is a commercially made aluminum sign about 18" wide by 24" high. Despite its mostly two-dimensional construction, it can talk and has lips that articulate while speaking. Here's a sample of what the bear can say:

The child-like voice originated from a Gund Peek-A-Boo Teddy Bear. It's a stuffed plush toy that was purchased from Amazon, but other retailers sell it too. I highly recommend this animated toy to all the little people in your family.

A pushrod connected hobby servo moves the mouth. Software synchronizes the movements to the voices stored in digitized audio files. Here's an inside view that shows the hidden servo:

MouthAssy2b_600.jpg

 

The open mouth was painted red. It appears white when the lips are closed. See photo below:

MouthAssy1b_600.jpg


Directly above the bear are a pair of marine rated speakers driven by a 30 watt audio amplifier. The audio quality is good with plenty of volume.

BearDisplay1_400.jpg

Between the speakers is a WiFi security camera for safeguarding the installation. Sad to say, but some people are angry at the world and might want to hurt this bubble loving bear. The recorded video should help ID anyone involved in any animal cruelty that might occur.

Visitor1_800.jpg

The Bear has a birds-eye view of the bubble play area. And his camera can see who is naughty and who is nice.

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There's a handful of electronic modules that do all the magic. Here's a photo from an early bench test.

ElectronicSystem1_800.jpg

 

The brains behind this talking bear is a ESP32 WiFi enabled microcontroller. It's mounted on a piece of Perfboard with two MOSFET modules (for driving the blower and wand motor). A high current relay is used to provide DC power to the 30W audio amplifier. Everything is mounted inside 3D printed enclosures.

ESP32_Receiver2_800.jpg


The pole mounted pushbuttons send an encoded signal to the Bear's 433MHz receiver. The receiver was originally mounted on the ESP32's perfboard, but EMI/RFI issues reduced the wireless button's range. So the receiver was moved further away. The photo below shows the placement of the ESP32 and receiver.

FrameRearView1_400.jpg

 

The off-the-shelf Audio Amplifier module uses a TDA7297 power amp IC. It provides two 15 watt channels and each drives its own speaker. Because contact with soapy bubbles was expected, marine rated speakers were used instead of common car speakers.

Speakers2_600.jpg


ESP32 projects that involve sound playback typically have some sort of audio hardware such as a MP3 module. But to simplify construction the audio generation in this design is software based. All thanks to the ESP32's onboard DAC and the open source XT_DAC_Audio library published by xtronical.com.

A mains powered 12VDC / 2A switcher supply (wall wart) runs everything, including the WiFi camera. Battery operation is supported too in case the Bear needs to play in the wild.

Here's the full schematic: Schematic.pdf

 

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It's time to wrap up this project's blog. I hope you enjoyed reading about my pandemic inspired panda.

Epilogue:
Joyful little distractions, like blowing bubbles, are a great way to shine a bit of light into our lives. Stay safe!

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