This video explains another FM Bug, with a higher range of operation.
This FM bug transmitter circuit will let you spy on people. The transmitter can be placed in the desired room and the conversation heard from a place far away just using a regular FM radio set.
The circuit is designed around a single transistor 2N3904 (T1), a custom-made coil (L1), three capacitors (C1 through C3), a trimmer (VC1), two resistors (R1 and R2) and, of course, a condenser microphone (MIC1). The circuit transmits in the frequency range of 88-105 MHz. Transmission range is 100 metres.
Working of the circuit is simple and based on analogue modulation in which a carrier signal is varied corresponding to the message signal.
 |
The microphone picks up the sounds in its vicinity to produce corresponding electrical signal. This is the message signal that needs to be transmitted over FM band. The message signal is fed to the base of transistor T1. The tank circuit made using trimmer VC1 and coil L1 generates the carrier frequency. This frequency can be tuned using the trimmer. Transistor T1 modulates the audio signal from condenser microphone over the carrier signal produced by tank circuit. This modulated signal is transmitted through the antenna (ANT.).
Using trimmer VC1, tune the carrier frequency in FM band and confirm it with an oscilloscope. You will hear the conversation picked up by MIC1 when you tune frequency of the FM radio set to match frequency of the carrier.
Prepare the coil L1 using about 25cm length of 25SWG wire. Wrap the wire around a cylindrical object of 6mm diameter and take it out after eight turns.
Assemble the circuit on a general-purpose PCB and enclose in a suitable cabinet. After proper soldering, fix switch S1 on the front side of the cabinet. Ensure that the oscillator is properly tuned. Addition of a dipole antenna will extend range of the FM bug transmitter. The circuit works off a 3V battery.
I’ll shortly start off building this circuit and will post the working details once the project is completed.
SHRIRAM SPARK 
Wow, this post is nice, my sister is analyzing these kinds of things,
thus I am going to inform her.
LikeLike
I think this is one of the most significant information for me. And i am glad reading your article. But want to remark on some general things, The website style is perfect, the articles is really excellent : D. Good job, cheers
LikeLike
WONDERFUL Post.thanks for share..more hold your fire .. …
LikeLike
Awsome blog! I am loving it!! Will be back later to read some more. I am taking your feeds also
LikeLike
Some really excellent information, Glad I discovered this.
LikeLike
I would like to thnkx for the efforts you’ve put in writing this website. I am hoping the same high-grade web site post from you in the upcoming also. In fact your creative writing abilities has inspired me to get my own blog now. Really the blogging is spreading its wings quickly. Your write up is a good example of it.
LikeLike
Thanks, hope i try to continue with this in upcoming future also. Blogging is really helpful, you learn a lot out of it, I would suggest you to start a blog using WORDPRESS [Though it’s my personal thought] as it is really very easy to maintain a blog and design it using WORDPRESS.
LikeLike
I needed to send you the very small word to finally say thanks again for your beautiful views you’ve provided here. It is certainly generous of you to give extensively all numerous people would have made available as an ebook in order to make some profit for their own end, particularly considering the fact that you could possibly have tried it in the event you decided. Those secrets as well worked to become a fantastic way to be certain that other people have the identical dream really like my very own to see great deal more on the topic of this condition. I’m certain there are numerous more pleasurable moments ahead for folks who discover your blog.
LikeLike
You are my inspiration, I possess few web logs and infrequently run out from brand :).
LikeLike
I was highly pleased to acquire this web-site.I wanted to thanks for your time for this amazing read!! I surely enjoying each and every little bit of it and I have you bookmarked to take a look at new stuff you blog post.
LikeLike
I’m commonly to blogging and i honestly appreciate your content. The post has certainly peaks my interest. I am going to bookmark your web site and keep checking for new data.
LikeLike
I just want to mention I’m new to blogs and really loved you’re blog site. Probably I’m want to bookmark your blog . You really come with wonderful well written articles. Kudos for sharing with us your web page.
LikeLike
I simply want to tell you that I am just all new to blogs and certainly liked you’re blog. More than likely I’m want to bookmark your site . You absolutely come with very good article content. Regards for revealing your web site.
LikeLike
Truly beneficial thank you, There’s no doubt that your readers would in all probability want far more items along these lines carry on the excellent function.
LikeLike