Introduction: Star Trek Wall Comm

In this instructable I will show you how to make a Star Trek (Original Series) Wall Comm that, when the transmitter is activated, will sound the classical wall comm boatswain whistle followed by 1 of 4 recorded original series on-board transmissions, thereby indicating that you have to go to the location of the rf transmitter, or any other decided location, you can then press the white comm button allowing you to respond to the transmitter. It can also sound TOS alert klaxon plus red alert lights when the red alert button is activated.

I will use it so my mum can just push a button that will signal me in my room and let me know to go downstairs. I can then push the white button to communicate and tell her "coming!" or something similar.
Otherwise she has to walk to the bottom of the stairs to shout: "Boys, supper!!" or, "Fred, go water the bottom garden!."

Step 1: Aquire the Materials

Ok, first up, get all the materials and items that you are going to need. Here is a list:


  • A white switch.
  • A red puchbutton.
  • Some cloudy transparent plastic.
  • A 24.5 * 19.5 * 4 cm (9.6" * 7.6" * 1.5") cardboard box.
  • Some orange, blue and grey spray-paints.
  • Some normal red paint.
  • A glue gun and glue sticks.
  • Some thin white plastic (or paper).
  • Fabric speaker cover.
  • A 3D Printer (Or just some cardboard/foam).
  • A metal big washer.
  • Some thick, strong cardboard.
  • Some aluminium supports.
  • Some baking parchment.
  • Some brown thin paper.


  • An Arduino UNO.
  • Six voice recording modules (ISD1820).
  • A load of male-female jumper wires.
  • A load of male-male jumper wires.
  • An 8 ohm speaker.
  • A 100 Ohm resistor.
  • Two cheap (preferably 9v) walkie-talkies.
  • A couple of red LEDs.
  • A couple of strong white LEDs.
  • Any old light bulb.
  • Two pushbutton.
  • Two 9v batteries
  • Two 9v battery connectors.
  • A meter or so of wire.
  • 30cm single-core wire.
  • 433Mhz rf links.
  • A perfboard.

For some of the main parts of the project, I just printed them out with my 3D Printer, for those of you who do not posses such an item, just make it out of cardboard or craft foam.

Step 2: The Mic/Speaker Enclosure

Now it's time to get started. The first thing I did to build this part, was design it on Google SketchUp. Here I have uploaded two files, one that has the model altogether, the way it appears on the show, and on the other, (the M1 file) the top section is separate from the side section, to simplify printing procedures.

If you don't have a 3D Printer then open up these two files and cut out your cardboard or foam in order to match the SketchUp file. If you do have a ·D printer and you want to use it to make this part of the instructable, then I've also uploaded two ".stl" files so you can print them. The P05 is the sides, and the P250 is the two top sections.
If you look at the photos, I have included two with all the measurements of the Wall Comm in inches that I found online, and you can see it from two different angles, this photo could help you throughout this instructable.
The .stl files may look a bit strange on the .stl viewer of instructables, but when you open it in the 3D printing software you have, it should be fine.

For those of you who are going to print, keep reading, and for those who aren't, skip to the next step.

Once you have printed out the two files then sand out the hole in the smaller top part, which now is a strange hexagon shape and needs to be a more ellipsed form. And as for the big rectangle on the bigger top part, also sand the corners to make them rounder. They must not be perfectly square.

When all the parts look how they are meant to, glue them together, putting the smaller top part on the slightly elevated fraction of the rectangle sides piece and glue the bigger top piece on the slightly lower part of the sides piece.

Now that that is done, the next step is to get the speaker cover material and stick it on the back of the enclosure, so that you can only see the material through the big rectangle. I secured it there with some hot glue, but any type of glue should be good.

Step 3: The Alert Screen

This step was one of the hardest. You have to make the Alert Screen that lights up red when you push the red button. First we will make the screen itself. The lights come later.
If you look at the photographs of the prop, you can see that it is a cloudy transparent, and that darn colour is hard to get.

After much trying i finally fell upon this old folder that was pretty close to the cloudy acrylic colour. So i measured out a rectangle 6cm wide and 5cm tall, and as for the sides, the two 5cm ones are 1.9cm on one side and 0,6 on the other. Then the 6cm top one is 1,9cm on each side and the opposite bottom one is 0,6cm on each side. then i roughly marked some little folds on all the sides to slip in the holes which we'll make on the main board.

If you do not have this kind of cloudy plastic then maybe you know how to cast resin or you work well with acrylic and can make a great looking alert screen (much better than mine), but since I'm neither of those things then I did it like this.

Step 4: The Buttons

Now it's time to make the buttons that notify the Arduino when someone has pressed them.

The top one measures 22mm diameter without the outer silver ring. I managed to find a red pushbutton that was exactly that size, I threaded it through a hole on the panel and cut very precisely a round piece of foam that I painted a realistic silver colour to act as the ring around it.

For the bottom white button, I just bought a white push switch and designed a ring to go around it, I've shared the ".stl" file. I then painted the ring black, this will go round the white button after screwing it through a hole in the main panel.

Step 5: Painting

Now that all the parts for the receiver panel have been finished we can paint them:

  • The Speaker/Mic Enclosure

This part is a type of greyish blue, I managed to achieve this colour by first spraying a layer of blue then one of grey, it didn't come out too bad. You can spray paint it directly with the speaker material on.
Then the last bit left to add is the white light cover on the left of the speaker enclosure. I made this by pouring some hot glue from the back of the enclosure, you have to make sure that the glue is very hot or you'll end up not filling the whole hole or get lots of bubbles. I recommend also that you put the enclosure on top of some baking parchment to stop the glue going out of the hole and ruining the paint, before it dries stick some white paper, I used some thin white plastic, this is to give it the white look instead of transparentish glue look. When completely dry take the Enclosure off gently and you should have a smooth finish to the glue.

  • The Main Panel

I made this panel with the 24.5 * 19.5 * 4 cm (9.6" * 7.6" * 1.5") cardboard box that I found, just to make it a bit stronger I cut a rectangle out of a notebook cover and stuck it to the underside of the box, along with some light aluminium supports. In the TV show it is an orangey-red colour. Before directly spraying it on I gave it a layer of black to cover up the writing on the box. Then a couple layers of orange. All in all it came out pretty well.

Step 6: The Transmitter Panel

Ok, this step is completely optional. I mean that you can just make it any way you want as long as it carries the walkie-talkie insides, the transmitter and a battery This part is the one that you would put in the place where the person would call you from. I made mine look sort of rustic to match my mom's country style open plan kitchen. And just in case one of you has the same kitchen or wants to make the same transmitter panel as mine then I'll briefly explain what it's made of and how I made it.

First of all I just took a box and made two holes and a horizontal rectangular opening, I covered said box in a thin brown paper, that gave it a woody look, the centre opening is for the light that will shine when the transmitter is on. The top hole is for a switch that will turn the transmitter and walkie-talkie on, and finally the bottom hole is for a pushbutton that will signal the receiver. Both buttons are well tightened to the box and on both I have screwed and stuck a nice sort of ring that I salvaged from some draw handles.

Then on the electronics side it was very simple, I just soldered the switch to a 9v battery that powered the transmitter and the walkie-talkie, and the pushbutton, when pressed, will allow current to reach the data pin on the rf transmitter. The antenna of the walkie and of the transmitter came out of the left side of the box that added a good-looking touch to the whole panel. The walkie's speaker was attached to a square hole on the right side of the box.
So what happens when the switch is switched is that the walkie starts outputting static through the speaker, as the other half is not turned on yet, the light lights up and the pushbutton is made ready to signal.

The final touch was to cover the two sides of the housing with the speaker material, therefore rendering the speaker almost undiscoverable.

Step 7: The Electronics

In this step I cover all the physical (not digital yet) parts that make the communicator work, I think the best way to do this is to show you all the connections that I've made, I know it's not very tidy, but it's the first time I've used Fritzing so please forgive me. I'm not going to describe all the wiring in words as that will get very confusing. I recommend you simply study the diagram. Additionally, when you look at the code in the next section, the wiring will become easier to understand.

But basically:
One of the two transmitter data pins I connected to Analog pin 3, and I supplied it's power via the Arduino's 5v.
As for the walkie-talkie, (that I obtained by taking apart some old nerf ones) I took of the spring on a pushbutton and pushed it in so that it would stay there (as seen in the last photo), this button allowed you to speak to the other walkie while you were holding it down. But this means that you can only speak to her and not her back to you, but this is fine in my case. I powered it by the 9v that would activate when an NPN transistor (I used the C549B) was based by the Arduino's digital pin 8 (called waltal in the code), but still you have to press the white push switch for the light to come on and the walkie-talkie to activate, like in the show; the transistor is for opening the window to activate it after everything has sounded.
The voice recording modules are all powered by the arduino's 5v and are controlled by the pwm pins 2, ~3, 4, ~5, ~6, 7.

I have posted a picture that I took of all the parts in the box, it's very confusing but maybe it will help a bit.

Step 8: The Code

Here is the code for the Arduino. This code will make the arduino randomly select a number from 3 to 7, corresponding to output pins that will activate one of four voice recording modules. This will happen after a voice module has sounded with a boatswain whistle, characteristic of this prop. Furthermore, the code will enable Wall Comm to respond to the transmitter panel, by activating the working part of a walkie talkie, but only when comm button is activated.

The one difficulty in this code is the sigVal part, because it is really hard to know when the signal has arrived, therefore you have to sit looking at the serial monitor while someone is in the other room pushing the button every minute, but after hours of sitting I finally saw that it was 3.66v repeated 3 times, that was what happened when the transmitter was activated. When you find your number amongst the serial monitor, multiply it by 1023 and divide it by 5 to get the final number that goes in the "if(sigVal >= 748) {" line, and depending on the times it repeats itself you'll want to change the "if(certainty >= 3) {" line.

If this code below doesn't work, try to download the file I've uploaded, this code gives you a "stray '\' in program" error sometimes but the other, that is the same but with less comments, doesn't.

long randNumber;        //Setting all the pins
const int sigIn = A3;
int certainty = 0;
float sigVal = 0; 
const int waltal = 8;
const int ABut = 9;
const int ALig = 10;
const int AKlax = 2;

void setup() {
  pinMode(AKlax,OUTPUT); //setting pin two for the alert klaxon 
                                            //setting 5 digital pins to output
  pinMode(3,OUTPUT); //for the other recording modules.
  pinMode(waltal,OUTPUT); //making the walkie-talkie pin an output
  pinMode(ABut,INPUT);    //And the alert button an input.
  pinMode(ALig,OUTPUT);    //Setting the red alert light to output
  randomSeed( analogRead(A1) ); //Making things really random.

Serial.begin(9600);  //Just so I could work out when we were receiving a signal.
void loop() {
  sigVal = analogRead(sigIn); //reading and storing the data of pin A3
  int ABV = digitalRead(ABut);   //Reading the Alert pushbutton.
  Serial.print("Voltage Output = ");
  Serial.println("  ");
  randNumber = random(3,7); //Getting a random number for the
                            //output voice module pins, exept the
                            //7th that will play every time
  if(ABV == HIGH) {         //Checking if the button was pressed
    digitalWrite(AKlax,HIGH); //If so sound the alert
    for(int i=0;i<6;i++) {
  else {                 //And if not keep ckecking for the signal.
   if(sigVal >= 748) {
   else {
      certainty = 0;
    if(certainty >= 3) {        
      digitalWrite(7,HIGH);        //Here we play first the whistle
      digitalWrite(randNumber,HIGH); //Then on eof the four other modules.
      certainty = 0;
   else {

Step 9: Make Space

Stick all the parts you have created on the main panel, following the photo above, and don't worry too much about the measurements, because there is no place where there are the original prop measurements, and even if there were, each prop was most likely different as they were made by hand, and probably by different people.

The alert screen i made four cuts with a stanley knife and slid the flaps in. And the actual comm part I made a hole behind, obviously, so that the speaker and mic can go there.

This part is every man for himself, now you have to put all the electronics into the box, the best way to do it in my experience is to get out the glue gun and 50 glue sticks and stick everything relatively organised to the back of the box, make two holes for the red leds that shine through the alert screen, and one big hole under the speaker material to fit the speaker right up to the material and the microphone as well.

Step 10: Enjoy...

There you have it, a perfectly functional, full sized, Star Trek on-board wall communicator. I hope you enjoyed making it and I hope you understood everything, if not then feel free to ask. This is my first instructables, so I'm sorry if I've made a few mistakes. Now get that panel on the wall and have some fun!

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