Mobile Phone Jammer Circuit Design Using 555 Timer With BF194 Transistor Replacement

sir, we are very much interested in design of jammer circuit, even we started working on it but there is some problem with our circuit i.e signal is not getting jammed... we are working on simple mobile phone jammer using 555 timer and we have replaced MRF494 transistor with BF194 ...
can u plz help us and provide us with details of particular circuit

Depends on what signal your trying to jam I suppose

A simple setup like that will not work because you have to cover a lot of frequencies see list below:

3G, 4G, MediaFlo, DVB-H 700 698–806
SMR iDEN, ESMR CDMA (future), ESMR LTE (future) 800 806–824 and 851–869
GSM, IS-95 (CDMA), 3G AMPS, IS-136 (D-AMPS) 850 824–849 and 869–894
Unknown 1400 1,392–1,395 and 1,432–1,435
GSM, IS-95 (CDMA), 3G, 4G IS-136 (D-AMPS) PCS 1,850–1,910 and 1,930–1,990
3G, 4G AWS 1,710–1,755 and 2,110–2,155
4G BRS/EBS 2,496–2,690
these are old and new plus all mobiles are designed to overcome bad noise from the environment.
And can burst output 5 watt so a simple design as above is not more then a toy.

Yes 5w is more than capable of jamming the phone, IFF it is directed energy. If your radiation pattern . If your radiation pattern is omni the 5w won't cut in practice so you really need to do one or both, direct your energy & or increase your power. I won't get into the antenna equations needed but they aren't all that difficult and can be found in hobby books.

In any event what you are doing is illegal unless you advise people what you are doing and then restricted. Also likely the power you need would require an FCC license, good luck there. Case someone calls 911 you jam them withouth their prior knowledge bad things could come your way. Just so you know.

As for unstable, if unstable is random, noise yes good, phones have a problem with that. If the unstable is some modulation , periodic, phones can get around that to some extent.

So you need power and direction. 50W omni would likely work anywhere in the phone's range and you get 3 squares a day in jail when caught.

from my experience, jamming a cell phone is not a simple task. your circuit is too simple. most of the parts required to make a jammer are not available in market as ic, or they are too expensive. if you would try to mannualy design the circuit using fet and transisiors, u need to design a pcb also. if you design this on vero board wire stray capacitance would come into play, and some radiation loss via connecting wires. antenna design for this high frequency is also too much complicated. try to extract rf amplifier ic and a cell phone antenna from a nokia cell phone. at 1st try to make a high power rf amplifier arround 200 watt. generate a signal arround 1900MHz using crystall oscillator, generate some noise voltage in another circuit. then use a fet audio mixer to mix a carrier signal with noise. then amplify it using the rf amplifier, and then brodcast it using a full wave horizontal dipole. good luck.........

feel free to ask any detail of fet, ic specification if needed............

interesting idea, but I think if you use the noise signal to _Frequency Modulate_ (instead of Amplitude Modulate) the carrier it would be more effective -- but, as Peter pointed out, there's more than one band of frequencies in use for cell phone communication, so you would need to do this for each frequency range.

BUT, have you considered the legal implications of such a device? Generating RF interference in these frequency ranges may be illegal -- and if your jamming signal bleeds over into other government controlled frequency bands, such as for aircraft navigation and such, you could face serious incrimination.

See overhere:
http://www.qrz.ru/schemes/contribute/security/jammers/jammer17.shtml

surely sir with frequency modulation. when there is a large carrier swing we can block most of the
cell phone network. we can jam the gsm band in 800MHz to 990MHz which include most of the service providers in india. but it is a power washing idea which dont even allow the emergency calls. we can add a microcontroler with a lcd display to set a frequency range reduce power consumption.

This is most likely illegal and more importantly dangerous as 911 calls would be blocked as noted above. However I do know that at one time theaters commonly had such devices to stop cell phone calls from disturbing other customers in the theater. I knew a woman who had a shop adjoining a theater and she couldn't use her phone during theater hours. I don't know how they got around the regulations or whether they still do it. I would imagine that if someone had a heart attack in the theater and help was delayed because a 911 call was blocked it would be a big deal.

Just one note about jamming - it does not effect the transmitter - just the reciever of the cell phone. Therefore 911 outgoing calls would not be effected. For cell phone jamming the basic concept is to over load the front end of the receiver so it can't pick up anything except your null single. Would be liking send CW but with not dots or dashes - just a constant carrier

How well can I make an emergency call if I can't hear any answer ?

Maybe its not a good idea for us to help people who want to engage in dangerous illegal antisocial activities ?

Who would actually want to jam our mobile phone networks on some particular occasion ?

Why does the name Al Quaeda come to mind ?

Yes, I do hope I'm sending shivers down all your spines !

Dangerous, Illegal anti-social activities and Al Quaeda may be a little far-fetched. Who knows what this is for. Myself, I'd love to see some way to limit cell phone use so I can listen to a movie, a concert or eat dinner in a nice restaurant without listing to other peoples phone conversations, which I guess makes me anti-social as well. Personally, many people's severe addiction to their cell phones sends shivers down my spine.

I do remember the times when we didn't have cell phones - maybe we should go back to those times. Like Stephen says - I would enjoy a dinner out or even at home without having to listen to one end of a phone conversation.

As for jamming cell phones - usually they are limited range - like a few hundred feet. unless you have a real powerful transmitter. Seems to me if you are Al Quaeda it would be much cheaper to take out the cell tower rather than the cost of the required electronics. Stick of dynamite is probably a lot cheaper.

The only people that want to jam cell phones are the ones that have something to hide or want to disrupt communications or are up to no good

Simple answer to a stupid question

It's always interesting to hear someone who knows ALL and can pontificate absolutely, unlike us mere mortals.

What about the theater case? Not that I condone that practice, but isn't that an example of a non-nefarious reason to jam cell phones?

I would guess the least malicious (and most common) case is kids who think its funny to make a nuisance of themselves to other people.
But as has been said, that can cost people their lives.
But I imagine a phone jammer would be standard equipment for the 21st century bank robber.

Stephen, it is a ridiculous idea to think that terrorists would hijack four planes in one day and crash them into important buildings. Or set off four bombs in one day on trains and buses in a major city.
It is scarcely far fetched to think they would want to hinder the emergency response next time by jamming everyone's phones.

The theatre case: debatable. What if a doctor in the theatre needs to be called urgently ?
Or if someone in your family is taken ill, would you rather sit there and enjoy the movie ?
But at least a theatre or restaraunt could have a clear sign informing their customers of the jamming.

David: "Stick of dynamite is probably a lot cheaper."
Not at today's prices for electronic components. (At least, from China.)
And which is easiest to get hold of without attracting attention, dynamite or transistors ?
(Ah, but maybe you live on the other side of the pond to me !-)

I carry a cell phone, but never even put the battery in except for emergencies.
But when I need it, I don't want it being jammed by silly kids or anyone else. Don't you feel the same ?

*SO* let's just check out the facts from our enquirer:

Priya, please would you tell us, why do you want to jam our mobile phones ?

Frank, in terms of the theater case being "debatable", you are off context. I was targeting Mark's assertion that a cell phone jammer "can only be up to no good". You're speaking in the context of why it's not a good idea. That is consequence vs motive. The theater owner's motive could be _innocent_ even in the presence of stupidity. Which, basically, means you are saying that "the _ends_ qualify the _motives_".

But, I agree that jamming cell phones is something to be done with great consideration and restraint. And it would be nice to hear your reason(s), Priya.

It seems that too many people are not so considerate and have no problem disturbing others with conversations, sometimes even loud personal arguments, so it may be that jammers have their place. Having been an EMT and first responder in a volunteer fire department for a decade I can see the issue with 911. However, it's not so simple.

The theater should have a land line and anyone involved with CPR or some such isn't the one who's calling anyway. The person who would call can go out and use the land line and then be by the door to help direct the EMTs. Emergency response in pubic venues isn't that common (have you ever seen it?) while rude people are all to common, unfortunately.

There are two sides and like everything there is no simple answer.

I agree that mobile phone use can be a nuisance to adjacent people, but activating a jammer just for personal peace is potentially dangerous and almost certainly illegal.

Steve L, I respect your motivational philosophical moral analysis, but yes, I am basically trying to cover practical aspects.
My suggestion is that, if many people had jammers, the results would be bad for many of us ! So I suggest we don't help people build them.

Stephen VB, if someone in a theatre collapses from a heart attack, it is likely to take from five to ten minutes for anyone to find the office with the land line ! And even then its probably locked.

And (in the most unlikely event) if some madman starts shooting people at a movie, isn't it good that anyone can *instantly* call the police ?
Have you ever seen such an emergency response in a public venue ? Yes, regularly if you watch TV.

This is getting far afield but I think you're exaggerating a whit to make a point. 5 to 10 minutes to get to a phone is quite a while, unless you stop for popcorn. Theaters generally have phones at hand, way closer than 5 or 10 minute3s, if only to call about drunk or belligerent customers.

I think that emergency responses are extermely rare, other than to traffic accidents and just in case (an ambulance commonly responds to all fire calls and they are rarely needed). That was true in our department.

I'm sure you can find out how many emergency responses your local department handles and guess how many public venues there are your area and calculate how rare. Ambulances can easily be ten miles from an incident and may be on a call. They can't just part traffic like parting the red sea. They're often lucky if they can average 30 mph (really - I've driven a fire truck and performed CPR in the back of an ambulance) so a minute or so of delay in the call may be insignificant.

TV's quite good at making people afraid. A single outrageous incident will be covered to death across the whole country of hundreds of millions of people. You're chances of dying in a theater, or from some crazed killer in a mall are less than your chances of being hit by lightning. Do you wear a beanie with a lightning rod and trail a ground strap?

All things are compromises. The quality of emergency responses is largely determined by how much money we want to spend, weighed against the likelihood of an incident. Many places have very long response times, or no coverage at all because people would rather spend their money on important things like social networking on their phones. By the same token, there is a trade off between dealing with rude people daily and the extremely rare chance of an incident.

I have an experience to share with you guys. Once I was in a remote place, my signal in my phone got jammed, i thought the problem would be with my service provider. After coming back home i gave black and blues to my customer care highlighting my issue. They pleaded me saying that the problem is not with them. Then i browsed through the search engine regarding my issue, i got a remedy for my cell phone, there i came to know the problem called signal jamming that is experienced in most cell phones. They have a product called cell phone jammer could be very useful to get rid of these problems. Check out the details here "need a cell phone jammer for a conference room(need a cell phone jammer for a conference room)":http://www.jammerall.com/categories/Cell-Phone-Jammers/ and hope this information would be beneficial. Hope that u would pass this information to all your friends, so that they too would benefited, Stay safe, Cheers

One more project:
http://www.ladyada.net/make/wavebubble/index.html

The *audio jammer* can be useful in our daily life. Especially when you want to have a rest and don't like to hear other people's talk in the phone,the product can help a lot.I just have a little knowledge about this new product.

Its very easy to think only of your own convenience and comfort.

But please tell me how you will feel, when you desperately need to make an urgent phone call, and someone is jamming your phone ?

Just because they happen to want some peace and quiet ?

Well, I'm not really sure just how many people DESPERATELY need to make an urgent call when they're in a theater, or why they can't just go outside, rather than disturb everyone around them. Why is it OK for one person to disturb many others? In this case I don't think I'm the one who is only thinking of my convnience an comfort.

While I find phones in theaters no more distracting than someone talking loudly or crying babies, but why are cell phones sacred? There didn't seem to be a huge problem with emergency calls from theaters before cell phones. How did people SURVIVE before cell phones?

Yes I do expect peace and quiet when I pay money to watch a movie - is that so hard to imagine? I didn't pay to listen to someone else talk over the movie, whether it's person to person or over a cell phone.

This is a pet peeve of mine -- attempting to rescue people from the unpleasantness of confrontation by applying a "technological solution". If someone has the effrontery to use their cell phone during a movie, it's for the audience to band together and oust the imbecile--then, en masse, to petition the projectionist to roll the movie back to before the disturbance.

The potential for both teaching a lesson, and for fostering friendships, is too valuable to replace with electronics.

Shielding people from their shyness with technology is not the answer!

Or, even better: how about if the audience, in unison, yelled, "Stop the movie!", and then queried the cell phone user, "Is this call of life threatening/life altering import?" That could lead to a conversation that either has the offender:

* leave the theater (if the usage was trivial and they refuse to reform)
* show signs of reform, in which case the movie is resumed, and the bugger ousted on a second offense.
* it _is_ an important call, and the audience is either treated to an episode of joy in this persons life, or is there to console this person in their moment of grief.

Our modern lifestyle tends to cut us off from one another. What if concessions were made to allow interruptions when truly momentous life events occur? What if we adopted a "human family" attitude about each other? What if our schedules allowed for such interruptions?

What kind of world would _that_ be?

The problem with a personal solution is that someone who is rude enough to use his cell phone in a theater, or talk loudly for that matter, is rude enough to cause an even bigger scene if you confront him. I have also found that cell phone users are more rude than loud talkers. They can't be expected to just hang up - THAT would be rude and EVERY call is important. Confronting a rude person ends up a bigger disturbance.

The other problem is that you may not be right next to the offender and people don't even try to whisper into a phone. For no reason I can see people are much more likely to shush someone who is talking too loudly, than to confront someone on the phone and calls can be interminable.

I see NOTHING wrong with a technological solution to a technological problem. Believe it or not, cell phones aren't a necessity. I think it was Ambrose Bierce that said that the telephone was a diabolical instrument allowing people you didn't want to talk to to reach you more easily.

bq). I think it was Ambrose Bierce that said that the telephone was a diabolical instrument allowing people you didn’t want to talk to to reach you more easily.

That is only true for people who cave into the compulsion to answer the thing