Regarding Cell Phone Jammers

ooh! ooh! I want one, too!

The surest way is to use rf seeking missiles to take out the surrounding cell towers.

Depends on the application. The easiest way to do it for a building is to just embed a Faraday cage into the walls. No signals can make it through. As for a portable one; the legality of that is really shady as it requires violating FCC regulations and broadcasting powerful enough signals over a wide spectrum to bath the spectrum in noise. Most cellphones use Spread-spectrum modulation and only need a small portion of the signal from any of @ 80 channels to make it through (really messy RF collisions in that section of the spectrum). The current technology was created to STOP jamming techniques; Hedy Lamarr the actress actually created the protocol to stop US torpedo's from getting jammed in WWII.

So, the answer is to encase the offensive cell phone user in a metal box. I like it.

An old wringer-type washing machine comes to mind...just insert cell phone between the rollers, and crunch! instant jam! This should work just fine with or without the attached hand. I feel your pain.I wish I could make a soup-can sized EMP generator to silence some of these MEGADECIBLE car stereos. My advice..buy hearing aid stock in the future.

I have one, but it only works with blonde bimbo trophy wives on their daily pilgrimage to Neiman Marcus.

-e

they are already designed and built and being sold by the hundreds to Gas Stations, Churches, Hospitals, etc

Where've you been Don?

-e

Who are you making this for?

When I was in college, one of my profs assigned a lab project for me to design a TV set jammer. He traveled a lot and hated hearing other people's TV's through the hotel walls. I wonder if he's updated that assignment?

the old analog ones were easy to defeat. Just a higher level signal on the discrete frequencies use by the decives so the desired signal was swamped.

The frequency agile digital ones on the higher bands require a large number of very close frequencies to ja, them that cover the whole band so the devices cannot find a slot to work in. With a few hundred frequencies in the band and you have to transmit a few watts on each to swamp the signal getting out. Easier to swamp the incoming signal as it is a lot lower.

They use these now to protect motorcades from cellular detonation of improvised explosive devices. They travel with the motorcade and create a 200 yard in diameter zone of non reception. Add more power = bigger zone. So the bad guys have to set the bomb off while it is more than the 200 yards mentioned away from the motorcade and use a time delay. The motorcades use speedups and slowdowns to confuse such tactics so the arrival time of the target at the detonation point can not be predicted.

most hotels have shielded cable system these days and even if you had a tranmitter it would have to be tunable and around 10 watts. Just turn it on and tune it until you hear the guy next door start to swear

The key to an effective TV jammer is to jam at the IF frequency (48 MHz if memory serves), not at the antenna. Or at least it was. Do TVs still have IFs?

Yes, TV still have IF's, but they are all in shielded cans these days as things are miniaturized with 1 IC = the whole IF and zero adjustments to be made.

That makes them less susceptable to interference of any kind.

The old TVs with a row of adjustable IF cans in the open were very jammable with IF transmissions

In fact in the UK the sniffer trucks have a hard time spotting the IF leakage that used to be how they found that you had an undeclared TV for the TV taxes.

The cat detector vans?

Hello!......Hello!....... This phones crap!

Are you sure that you want to "jam" a cell phone, dragonfury? In the United States, the operation of transmitters that are designed to block wireless communications is a violation of the Communications Act of 1934. So, if you want to avoid trouble with the FCC, take a look at this article and let the community know that what you really mean is "passive blocking".

I want a device that makes them get very hot and emit smoke.

People would yank those suckers out of their pockets real fast

So I would really like to encourage everyone to stop responding to this question until dragonfury tells us for whom and why he wants a cell phone jammer. Such a device would be very useful to a terrorist who wanted to hurt communications to either facilitate an attack or create confusion in the wake of an attack.

You should also note that this is dragonfury's one and only post in several weeks, meaning he created his account only to ask this question. The whole thing is kind of suspicious if you ask me.

short range cell jammers were easy on the 900 mhz analog band. On the new digital bands it is a lot harder with the new frequency agile small cell systems.

You can get them. Israel makes lots of them to suppress cell phone detonators. They make a signal on all possible receive freqencies a cell phone can get and create a zone within which a cell phone is silent. The zone can be 500 feet across or more...just add a broad band 250 watt amplifier to a multifrequency signal generator and it will put put a few watts on every channel

Please........... would anyone help me in finding a "basic" jammer circuit.

May be its out of date and found less effecient........ I dont mind!

I'm new to this! I want to know more.

http://www.google.ca/search?hl=en&q=%22cell+phone+jammer%22+%2B%22how+to+make%22&btnG=Google+Search

Before you make this, go to the local police station and ask them to let you eat some prison biscuits

Thank you for that info!

Further ..........Indian prisons dont provide biscuits! They provide some sought of gel it would take our life span investigating what it is.

Can anybody help me finding a low price VCO with range 900 - 1800 MHZ?