DIY Mini Spy FM Radio Transmitter

Hi, this is Kedar here. We are going to make a FM transmitter bug spy that will transmit the audio onto FM frequencies.

This bug is impressively tiny, so you can you fit it in any kind of space and you can hide it quite easily. Also, it has a rechargeable battery which can last for 50 minutes of use. You can also adjust the emitting frequency to your choice. So let's get started!

Before you go on, I recommend watching the full tutorial and test of this FM transmitter.

Step 1: Challenges to Making a Small FM Transmitter

If you do a quick little Google search for the FM transmitter circuit, you will get quite a lot of results, and they work really well if you prototype onto your bread board. But the biggest problem is the size. No matter which design you choose, the size will be at least as big as your FM transmitter.

So, I was searching FM transmitter on eBay and I found this very tiny and really interesting FM transmitter module. This module has a built-in microphone and adjustable frequency potentiometer. So, I decided to buy this and test whether it works!

Because it's size is really tiny, I bought these parts.

• FM Transmitter Mic http://amzn.to/2iMRodj

• 3.7v Lipo Battery http://amzn.to/2iN00kd

Step 2: How to Make A FM Transmitter Bug

Well, this is one of the easiest DIY project I have ever done!

1. Take Your FM transmitter microphone circuit and hook up a 3.7 volt battery at its positive and negative terminals.

2. A cheap alternative to the LiPo battery, you can use two 1.5v button cells in series.

3. Middle terminal of this board is your antenna. Without an antenna its range is very limited. There is no antenna that is ultra small and can still do the job of increasing the range, so I found a solution by making an antenna yourself.

4. I used a conductive copper foil tape, which can be stuck onto the back side of the battery in a plus shape like shown in the picture. After that, solder it to the middle terminal of FM transmitter board. So there it is guys, your FM transmitter is ready now!

Step 3: How to Broadcast Your Voice on FM

Check check mic check...

Okay, friends. If you followed each step perfectly, your voice should be already transmitting onto FM frequencies, so be a little careful!

Anyway, in order to find what frequency onto which your FM transmitter is transmitting on, you can use any kind of a FM receiver. I used my smartphone since it can also record my audio.

You can use the auto-scan feature to scan through channels. Eventually, you'll find your own voice coming through FM receiver.

You can also do this the opposite way. You can adjust the frequency on your FM transmitter bug. You'll need to use a small trimmer potentiometer screwdriver and gently turn the potentiometer anticlockwise; don't force it too hard or it might break.

Step 4: How's the Sound Quality and Range?

Guys, this is a very common question. As for the sound quality and how far it can reach, you can experience what I am talking about by listening to the sound quality tested in my video.

The mic is really sensitive - I mean it can even capture a pin drop in silence. So if you place a transmitter in one room, it can still hear the next room. Also, if anyone is whispering quietly, you can still hear their voices clearly. I doubt you can use it as a wireless mic for your DSLR.

The FM transmitter range is about 10 to 30 meters. It depends on the size of the small copper foil antenna. It will get you 10 meters, and if a person is holding this FM transmitter, their whole body acts as an antenna and you may get up to ~20 meters of range. A nice, dedicated antenna will give you up to ~30 meters. That's not bad - I mean, take a look at its size!

Step 5: 007, Think Like James Bond!

Now you have ability to spy on anybody, and you have no reasons to say no. If you have the money and you have a soldering iron, get the parts and try this for yourself. You can hide this one because of its size. I think it can go in any kind of space, just don't get afraid when you hear a shocking secret from someone.

So there's it is, guys. I always bring you fresh and cool DIY projects. Now it's your turn to share my project with your best friends and do a little favor for my videos. Check out my YouTube channel. You are awesome!

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