Get the same Megaphone here to build your own!
You will also need a 1/8" audio jack and a pair of headphones/earbuds. Some wire and standard tools, soldering iron, snips...etc.
OPTIONAL: 1/8" Y-Adapter and MP3 Recorder or other small device with Line-input.
Step 1: Disassemble the Megaphone
1. After opening up the battery compartment you will see 1 screw. Remove it and the battery compartment and circuit board assembly will come out as one piece.
2. Unplug the 3 connectors. Make a note where the white connector is as there are 2 2-pin connectors.
3. Remove the 3 screws that hold the body to the horn and remove the body.
4. Remove the single screw in the center of the horn. This will release the speaker.
5. Drop the speaker out and remove the 3 screws holding the horn on to the speaker
6. Unsolder the two connections at the speaker. Remove the speaker and save the white 2 pin connector.
Step 2: Modify the Microphone
1. Remove the two screws that hold the microphone case together and unsnap the case.
2. Using a sharpie, make a mark on the microphone's black wire. That's the Negative (-) connection. Also, if you look closely you can identify the Negative connection by observing the traces that go to the microphone case.
3. The microphone should pull out from the case insert. Put it in a safe place.
4. Drill a small hole in the side of the bottom microphone case to fit the 1/8" audio jack.
5. Solder the red (+) and black (-) wires to the positive (+) and negataive (-) contacts on the audio jack.
6. Install the jack in the case and close the case, reassembling it with the screws.
Step 3: Modify the Horn
Next, we will be installing the microphone in the horn.
1. The microphone will not fit in the existing screw hole in the horn that held the speaker so it needs to be drilled out. A 7/16th drill bit works perfectly. Carefull drill out the hole.
2. Insert the microphone in the hole and seal it with some hot glue.
Step 4: Modify the Wiring
1. Cut the white/clear wire and the red wire about 2 inches from the 4-pin connector.
2. Solder the two white wires from the 2-pin white connector wire we removed from the original speaker (Step 1 #6) to the two loose ends of the white/clear and red wires you just cut. (Don't solder it to the two remaining wires on the connector)
3. Cut two lengths of wire about 6" long. Solder one wire (in my case, black) to the white/clear wire and one (in my case, red) to the red wire at the 4-pin connector.
4. Solder the other ends to the microphone in the horn. Red to positive (+) and black to negative (-).
Step 5: Re-assemble the Megaphone
It's time to put it all back together.
1. Re-assemble the body to the horn with the three screws.
2. Plug the 4-pin connector back on the board and the 2-pin white connector. Leave the black connector unplugged as that is the Siren and we won't be using that.
3. Install the circuit board/battery compartment.
Step 6: Start Spying
1. Install the batteries and close up the case. Attach the microphone to the holder and insert your headphones.
2. Try it out! You should be able to hear a pretty good distance away. I got about 100 feet of distance.
Additional Tips: If you used a better microphone you would probably achieve a greater listening distance and audio clarity. Paint the Megaphone either black or camo.
I hope you enjoyed this Instructable! Have fun, be safe and use this responsibly.