Male speaker: Let's turn this Megaphone into a bionic hearing spy device. We will be using a 25Watt megaphone and if you like this project, well there is a link on kitkay.com where you can pick up the same megaphone and build yourself.
The first step is to disassemble the megaphone. So we will remove the microphone from the bracket, open up the battery compartment and remove the batteries and then there is a single screw that removes the battery assembly and circuit board. Unplug the three connectors attached to the circuit board and then there is three screws that hold the rear half of the megaphone to the horn. Those need to come out as well. Then remove the one small bolt that holds the speaker assembly in place and when that's free, you can remove the screws that hold the cone over the speaker. Once there, unsolder the two connections at the speaker and hang on to that cone speaker on for a future project. Remove that white connector and hang on it, we are going to need it in a sec.
Now its time to tackle the microphone portion of the megaphone. There is two screws that hold that in place and then the cover snaps off. Then make a mark with a sharpy on the negative side of the microphone. So you know which is which and then after desoldering the two connections of the microphone, remove that from the housing and hang on to it. I picked up a mini jack and drilled the hole in the side of the microphone case and wired it up with the original red and black wires we removed from the microphone. And now you can reassemble the microphone case.
Now we will be replacing the speaker with the microphone element and it's not quite small enough to fit in the original hole. So, that's needs to be drilled out a little bit larger and then it fits nice and snug and I used some hot glue to make sure that doesn't back out and now its time for some reverse amplification.
We are going to take that four pin connector and we are going to cut the white and red wire. Solder our original white connector leads to the two existing red and white wires we just cut, then solder your old lines of red and black wire to the red and white wire coming from the connector and the other end of the red and black wire gets soldered to the microphone. Okay, we are pretty much done, its time to reassemble our megaphone, but everything back together and when you come to the circuit board, don't forget to attach the two pin white connector to the circuit board, the four pin connector the circuit board and we are going to end up with one black two pin connector. Don't plug that in because, that goes to the siren and we don't want to hit this siren switch by accident and blow out our ear drums.
Then reinstall the circuit board battery compartment, install our batteries and close it up, attach our microphones at the bracket and then plug in your favorite headphones. Now you also may want to use a Y adapter which will let you plug in your headphones and then also attach a recordable device like an mp3 player with a line input. So you can record what you hear. And now the test results. I was amazed that I was able to pull in a conversation about a 100 feet away.
Female Speaker: Hi mom how are you?
Female Speaker: Yeah it's a beautiful day. I am just out walking the dog.
Male Speaker: And I tried it inside too, placing it up against a wall, I could hear faint conversations. And that's how to make a bionic hearing spy device.
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