How to Make a Wireless Tin-Can Telephone! (Arduino Walkie Talkie)

65,793

468

37

Introduction: How to Make a Wireless Tin-Can Telephone! (Arduino Walkie Talkie)

About: Hi! I'm Geoff! I'm an electrical engineer with a passion for making things. I believe that creating is for everyone, and I love being able to share what I've learned to enable others to pursue their passions. …

Just the other day, I was in the middle of a very important phone call when my banana phone stopped working! I was so frustrated. That’s the last time I miss a call because of that stupid phone! (In hindsight, I may have gotten a little too angry in the moment, see pics)

It was time for an upgrade. Enter the wireless tin-can telephone! The all new and improved gag phone, for all my fake communication needs!

Note: (This project does actually work)

Here’s how I built it!

Step 1: Tools and Materials

For this project, you’re going to need quite a few electronics, and a couple tools.

I'd like to disclose that this project was sponsored by DFRobot. All of the parts were provided by them, and some of the links provided are affiliate links to DFRobot. Feel free to use them if you would like to support Facio Ergo Sum! Off-brand parts work as well. Thanks to DFRobot for making this project possible!

Tools -

  • Drill (w/ Bits)
  • Tin Snips
  • Hot Glue Gun (Careful: Very Hot)
  • Needle Nose Pliers
  • Ball-peen Hammer

Materials - (Two of all of These)

Step 2: Prepping the Cans

Before we can wire up the electronics, we’ll need to prep the cans. To do this, we will be drilling two holes, one for the antenna, and one for the button.

I started with the antenna hole. First, I placed the antenna board inside the tin can, to measure how far from the side the hole would need to be. Then, using my finger to note the ridge, I marked the hole with an Whiteboard marker, so that I could wipe them off later. Then, using a tap, I put a small indentation where I was going to drill. This will help guide the drill in the next step.

Depending on the antenna you use, you may need a smaller/larger hole. So what I did to find the right size, was compared the threads on the antenna to the drill bit sizes.

Note: (Mine ended up being 7/32)

Alright, SAFETY GLASSES ON!

Once you’ve picked a size and marked out the hole, drill into the can, go at a high speed, but don’t push too hard. Because of how flimsy the tin can is, it will usually shear, so watch for sharp metal. Use tins nips and pliers to clean up this edge.

Then it’s time for the button hole. This one’s a little different.

Note: I’m working with what I have, so I decided to attempt it using the drill and tin-snips again. A Forstner bit might work much better. Here’s how I did it.

First, I unscrewed the plastic “nut” from the button. Then I placed the nut onto the location I wanted the hole, and marked the inside diameter. Then I drilled five holes, and used tin snips to clean the material out and form it into a circle. Mark the hole, tap it, and drill.

STOP! It's HAMMERTIME!

After this, I used a hammer and pliers to knock in the metal tabs and bend them down. Please refer to the images for a better idea of how I did this. I’ve provided a shoddy diagram that should be able to help you out.

Note: I suggest using a ball-peen hammer. I used a regular hammer because that’s all I had.

Once that’s done, you can screw in the antenna and the button. Again, be careful of any sharp metal bits!

Step 3: Hot Glue Gun Time!

Now let’s glue in the components!

First, plug in your hot glue gun and wait for it to heat up.

*Jeopardy theme begins to play...*

Then, use hot glue to secure the antenna board against the can. I also suggest coating the metal part of the antenna that sticks through the can with glue, so it won’t ground out to the can.

Note: With all of these components, use copious amounts of hot glue, so nothing has the chance of grounding with the can. If you hear a buzzing or beeping noise when testing it, you probably have a ground fault.

Glue the Arduino Uno to the bottom of the can, and then attach the battery pack. This will be the heaviest part, I suggest apply glue to the edges and then placing it where you want the can to rest (so the antenna points upwards). The battery pack will always be the natural center of gravity for the can.

I glued the speaker on one side of the battery pack, and the microphone on the other. (Refer to the pictures) This was primarily for aesthetic purposes, and wire management.

Make sure to use lots of glue so that none of the pins ground to the tin can.

Step 4: Wiring the Circuit

Once everything is securely glued in, it’s time for wiring! Use the provided schematic to connect all the jumpers to their appropriate pins. I’ll also provide the pin-outs below:

(Note, this is for the Gravity Expansion HAT)

Antenna Board:

  • MI -> MISO
  • MO -> MOSI
  • SCK -> SCK
  • CE -> Pin 7
  • CSE -> Pin 8
  • GND -> GND
  • 5V -> 5V
Something to note about this board. The NRF24L01 is a wonderful piece of technology, but very sensitive to electricity. Make sure to only power it with 3.3V unless you are using the included backpack like I am. ONLY CONNECT TO 5V WHEN USING THE EXTRA BOARD, otherwise it will fry the antenna.

Analog Sound Sensor:

  • Gravity Pins -> A0

Audio Amp:

  • +(on the speaker input) -> 9 or 10 (left or right audio)
  • -(on the speaker input) -> GND
  • Gravity pins -> D0

Switch:

  • NO -> A1
  • COM -> GND

Here’s a brief explanation of the circuit (to hopefully benefit anyone using a different board).

Because of the RF24Audio Library we are using, there is a very specific pinout for the microphone, speaker, switch, and antenna:

The Microphone signal pin will always go on A0 pin.

The Switch (for switching to transmission mode) is always the A1 pin.

The Audio Amplifier I’m using doesn't matter where it’s plugged in, as long as it has power. What matters is the wire you are using for audio transmission, which by default will be pins 9 and 10 (for left and right audio).

The Antenna pins CE and CSE are always connected to pins 7 and 8 respectively (which is what allows both directions of radio signal)

Hopefully this information will help you wire this circuit on any board.

Step 5: Pushing the Code

It's time to push some code! The program for this project is SUPER simple thanks to the RF24Audio Library. It’s literally not even 10 lines of code! Take a look:

//Include Libraries
#include <RF24.h>
#include <SPI.h>
#include <RF24Audio.h>

RF24 radio(7,8);    // Set radio up using pins 7 (CE) 8 (CS)
RF24Audio rfAudio(radio,1); // Set up the audio using the radio, and set to radio number 0. 

void setup() {      
  rfAudio.begin();    // The only thing to do is initialize the library.
}

I won’t be explaining how it works here, but if you’d like to learn more about Arduino IDE and what this code means, check out this link.

You'll also need to install the RF24 and RF24Audio Library as well, which you can download here.

Once you’ve got the Arduino IDE installed, download the Arduino program provided, and open the code. Look under the Tools drop-down. Make sure “Programmer” is set to AVR ISP, and Board is set to Arduino UNO (or whatever board you are using). Also confirm that you are on the right Port (it should say “Arduino Uno on COM#”)

Now we are ready to push the code. Plug in a USB cable to the Arduino and the computer, and click the Upload arrow in the top left of the IDE. The code should upload and you may hear a quiet buzz.

Try pushing the button and see if the buzz changes pitch. It should also dim an LED on the top of the IO Expansion HAT.

If you are getting these results, then the program should be running correctly and everything should be connected the right way.

Step 6: Testing It Out

To test it out, you’ll need to turn both cans on. Press the button down on one can, and make some noise into the microphone. Can you hear audio coming from the other can?

Try the same thing on the other can. Hear anything?

If so, it works and you’re done! Note: If you’re getting interference or buzzing, check for grounding problems. Make sure none of the leads are touching the can, and that there’s plenty of glue between components. Try to avoid twisting around each other, as this will increase interference. I also suggest covering the metal part of the antenna with electrical tape to prevent it from grounding to the can.

Once you know it works, try to test the distance too; it should go up to a kilometer if there’s nothing blocking the signal!

Step 7: Conclusion

Congratulations, You’ve made it to the end! Awesome job building this project!

Thank you for reading my Instructable, I hope you enjoyed watching the video and I hope you found it very entertaining.

I’d like to disclose that this project was sponsored by DFRobot, they made it possible for this project to exist by supplying all of the parts, so feel free to go give them some love!

Update: I’m entering this Instructable in the Arduino Competition, so if you enjoyed this project, please give it a vote with the orange button down below!

UpdatedUpdate: I’m also entering the Arduino Make-From-Home Contest, so I’d love if you could go show me your support on those sites as well!

Updated Update on the Previous Update: I'm also in the Hackaday.io Making Tech at Home Challenge, so go vote for it here!

Follow me for more cool projects like this, and go make something! Always keep learning. :)

- Geoff M.

Facio Ergo Sum: "I make therefore I am"
Arduino Contest 2020

Runner Up in the
Arduino Contest 2020

1 Person Made This Project!

Recommendations

  • Reclaimed Materials Contest

    Reclaimed Materials Contest
  • Halloween Contest

    Halloween Contest
  • Robots Contest

    Robots Contest

37 Comments

0
cafemiguel
cafemiguel

5 months ago on Introduction

Fantastic project, complete with all it's simplicity; It took me back almost 100 years; my first electronic project was a true high impedance microphone using the carbon core from the old tall 6 volt cylindrical batteries, I got the full build steps from some mid 1940's popular mechanic or popular science magazines I found in our attic, there were hundreds of them; they worked so well you could hear the footsteps of a cockroach or the flapping of the wings on a fly, you could also hear the "THUMP" sound when they landed; I believe I will build these for my grand kids to play with each other; I'll try and keep you updated on my progress, we do have to accept & learn HOW to use ARDUINO'S.

0
BerenV
BerenV

9 months ago

Nice project and very funny! Did you actually do any real range tests on the thing though? Yes, we all know that those nrf24l01 modules with the power amplifier and duck antenna claim “up to 1km” range, but in reality they usually fall way WAY short of that if you don’t do the shielding right (and/or try to transmit at high data rates which I imagine this project does). I’ve always wanted to try piping audio over these things, so thanks for writing a good example to look at!

0
tr0lldr0id
tr0lldr0id

9 months ago

I don't have the time to make this, but there's always time for gucci memes... Awesome idea! It's stuff like this that keeps me making things.

wirelesscans.jpg
0
BeardyTechie
BeardyTechie

9 months ago

I love this high tech take on an old idea.

I think it would be fun to have a frayed piece of string dangling out of the back of the can, as if it was a string can phone but the string broke.. maybe you could somehow disguise the antennae as bits of string?

Cool idea making can-string phones wireless. good instructable, like the video

0
justbennett
justbennett

Reply 1 year ago

Ahem... stringless.

0
sombramaligna
sombramaligna

1 year ago

I like it, great project. And could be used in other things.

0
CBedll
CBedll

Tip 1 year ago on Step 2

Save several steps and get a better result: us a Step-Bit drill. Well worth it!

0
JohnM1318
JohnM1318

1 year ago

I don't know what is better? Your tin-can phone OR your video skills! Too funny! This just solved my problem of me being in the garage and the wife not calling me in for dinner! Thanks!

0
Facio Ergo Sum
Facio Ergo Sum

Reply 1 year ago

Thank you! My mom always used a really loud bell to call us in, although I did grow up on a farm 🤣

0
JohnM1318
JohnM1318

Reply 1 year ago

I grew up listening for that same bell, on a farm, in NW Ohio! But the dinner bell would violate the neighbors' right to quite. Germany has no weird laws about things being loud.

0
Facio Ergo Sum
Facio Ergo Sum

Reply 1 year ago

That's awesome! My mom had the handheld one (as opposed to the wall-hanging one) but it was still very loud 😂 We never got noise complaints

homart-dinner-bell-cast-iron.jpg
0
1234567guy
1234567guy

Question 1 year ago

As a beginner, can I make one of these?

0
Facio Ergo Sum
Facio Ergo Sum

Answer 1 year ago

Absolutely! As a matter of fact, I *recommend* that you start with this project! There's no soldering required, it's a very simple circuit, and it's a small number of components. I designed it with beginners in mind ;)

0
Facio Ergo Sum
Facio Ergo Sum

Answer 1 year ago

Hah, I've been considering making an actual custom PCB version that's a bit easier to put together... But the whole idea behind the project is to make it yourself! :))

0
edthedaddy
edthedaddy

Question 1 year ago

why can't you use the nano on this one? would be much cheaper than the uno.

0
Facio Ergo Sum
Facio Ergo Sum

Answer 1 year ago

You can! I just used the Uno because I was using Gravity sensors. The Nano should work just as well ;)

0
zvizvi
zvizvi

1 year ago

too nice! definitely going to build one myself (kids & mom being 500 meters away). Thank you so much for sharing! and neat selection of components, too

0
bigbigdave
bigbigdave

Tip 1 year ago

Awesome project! Nicely done. The whole "slightly-scary big hole with lots of sharp jagged edges" part compels me to suggest you look into the wonder that is the Step Drill Bit (sometimes called a "uni-bit"). Available a bazillion places, cheap, easy, and THE tool for drilling thin materials.

This is just typing "step drill" in Amazon, but it'll show you what I'm talking about: https://www.amazon.com/s?k=step+drill&ref=nb_sb_noss_2, and here my lovely assistant Adam shows them in use: https://youtu.be/A3-9Vk_2be4?t=1170 If you'd like an explanation of how they work, rewind that video to the 17:55 mark.

Excellent Bobby Duke homage, as well!