Halloween is coming up. So it's time to start building projects to scare and prank your friends. In this project, I am going to show you how to make a TV appear to be haunted using a pair of walkie talkies. One walkie talkie is hidden inside the TV. When you speak into the other walkie talkie, your voice will appear to come from the TV.
Step 1: Open Up the TV
Before you do anything else, UNPLUG THE TV!! We don't want anyone to die while building this project. It is supposed to be a fake ghost after all.
With the TV unplugged, it is probably safe to open up the housing. However, keep in mind that some of the capacitors may still hold a charge for several hours after the TV has been turned on.
Once the housing is open, take look inside. Look for large empty spaces where you could fit a walkie talkie. Old CRT (cathode ray tube) TV's will give you the most space to work with. However, it may also be possible to use newer flat screen TVs.
Step 2: Select a Pair of Walkie Talkies
There are a lot of different kinds of walkie talkies to choose from. The exact kind of walkie talkie that you use doesn't really matter. But it is important to that you have two walkie talkies that are compatible with each other.
I am using a pair of Spy Gear walkie talkies that I picked up at a garage sale. I chose these walkie talkies because they are small and will be fairly easy to hide in my TV.
It is possible you make this prank work with cell phones. But this is less practical because you can't use your phone while it is in a TV.
Step 3: Modify an AC Adapter to Power the Reciever
You could power the receiver with the standard 9V battery. However, the short battery life will severely limit how long you make this prank work. So I designed a simple 9V power supply that will be able to power the receiver using the TV's AC power line. With this power supply you can run the receiver indefinitely. Here is how to make it.
These are the materials that you will need to make a simple 9V power supply:
AC Adapter with an output of at least 9V DC
LM317 Variable Voltage Regulator
1.0 µF Capacitor
0.1 µF Capacitor
240 ohm Resistor (or two 120 ohm resistors)
1500 ohm Resistor for a 9V Walkie Talkie (for 7.5V use 1200, for 6V use 910, for 4.5V use 620 and for 3V use 330)
Assemble the parts on a small perf board according to circuit diagram shown above. Connect the AC adapter to the circuit's V(in) terminals and you will have a 9V power supply that is capable of running your walkie talkie. For a more in depth discussion of this circuit and how you can assemble it, you can check out these two instructables where I show how to make custom power supplies with a voltage regulator.
Convert Battery Powered Electronics to Run on AC:
Step 4: Connect the Power Supply to the Walkie Talkie
The easiest way to connect your power supply to the walkie talkie is to add a 9V battery connector to the output of the power supply. This will easily snap to the connector on the walkie talkie.
When doing this, you need to remember to solder the black wire to the positive output and the red wire to the negative output. This is the opposite of the normal convention of red always being positive and black always being negative. But it is necessary to match up with the appropriate connectors on the walkie talkie.
Step 5: Add an AC Outlet Plug to the Power Cord of the TV
Now that you have a 9V adapter for your walkie talkie, you need a way to get power to it. The easiest way to do this is to add an AC outlet plug to the TV's power cord inside the housing.
Follow the power cord from where it enters the TV to the place where it is soldered to the main circuit board. Cut the cord at the midpoint of this section. On each side, separate the two wires by cutting the insulation between them and peeling them apart. Then strip about 1/2 inch of insulation off each end. This will give you four bare ends.
Take a second power cord and cut a few inches from the female end. Then again separate the two wires and strip 1/2 inch of insulation off the end. Now match up the bare ends of these wires with the others so that one side of each cord is grouped together as shown in the picture. You should now have two groups of three wires each. Connect each group together with twist-on wire connectors. Make sure that all bare wire is properly covered by the connector caps. This will have reconnected the TV's power cord and with a female plug added in the middle. You can use this to plug in your power supply and continuously power the walkie talkie as long as the TV is plugged in.
Step 6: Insert All the Parts Into the TV
Now all you need to do is insert the parts into the housing of the TV. Ideally you want to place the walkie talkie's speaker near the TV's speakers to create the illusion that the voices and sounds are coming from the TV itself. If necessary, you can tape the components to the walls. Make sure that there is enough space around each part that the housing can close without hitting anything.
Step 7: Optional: Make the Walkie Talkie Smaller by Removing Its Housing
The amount of empty space inside a TV varies a lot from model to model. If you find that there isn't enough space to fit the whole walkie talkie, you can make it smaller by taking it apart. After removing the housing, the internal parts only took up about half as much space as the whole walkie talkie. However, if you do remove the housing, you should wrap the circuit board and any exposed metal contacts in tape. This will help to avoid accidentally shorting either the TV or the walkie talkie.
Step 8: The Finished Haunted TV
With the receiver in place, you are ready to make your TV appear to be haunted. When you speak into the transmitter, a strange voice will come out of the TV. For the best effect, start making sounds that are subtle and gradually increase the intensity. Then when they try to turn off the TV, continue to make creepy sounds and voices.
Depending on the model of walkie talkie that you are using, there may also be the faint sound of static that will continue after the TV is turned off. Although this may just make them think that their TV is broken.
If the TV is an older model that uses an antenna, then you can make some additional effects. A walkie talkie transmitting near a TV antenna can interfere with the reception and create a lot of static on the screen. This can also be used effectively to creep people out if you have good timing.
Use your imagination and have fun.