Low voltage "jamming" for practical jokes - Page 1
Forum section: electronics / rf-microwave

author: MarcusFunt
author_rank: Contributor
timestamp: December 08, 2023, 09:28:48 am
content: Hi all.I want to create a simple, cheap RF wifi jamming board for doing practical jokes on my mates. I found the attached schematic online and wake to ask some questions.What modifications would be required for it to work at a lower voltage(preferably a 3v coincell).The crystal is only rated for a fairly low frequency. Will the circuit even work?Can I directly attach an antenna to the output of the circuit to transmit RF??The range should only be 20-120cm, to not get in trouble. How do I change the power?I would like for L1 to just be a simple smd inductor. What value and power should it be??Any assistance would be greatly appreciated.Thanks!

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 08, 2023, 09:47:24 am
content: This will not do that! It will produce a signal every 96.015 MHz and none of the harmonics will even fall inside the 2.4 GHz WiFi band.

author: MarcusFunt
author_rank: Contributor
timestamp: December 08, 2023, 09:54:35 am
content: What if I change the crystal to a 24 or 240 MHz one?

author: PA0PBZ
author_rank: Super Contributor
timestamp: December 08, 2023, 09:58:56 am
content: The WiFi band is (depending on the region) 60MHz broad, you need a different technique to block that. No, I'm not going to tell you how, but you'd need a lot more power than a coin battery could provide.

author: p.larner
author_rank: Frequent Contributor
timestamp: December 08, 2023, 04:41:24 pm
content: look for uhf spark transmiter schematic,or better stil disable your microwave oven interlocks and fire it up with the door fully open,then see if you can get nominated for a darwin award.

author: rhodges
author_rank: Frequent Contributor
timestamp: December 08, 2023, 04:43:49 pm
content: If you want a prank, how about programming an ESP32 to send insulting messages as the SSID?

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: December 08, 2023, 08:30:43 pm
content: Link to WiFi Jammers:https://www.wxyz.com/news/oakland-county-sheriff-to-announce-new-regional-task-force-to-combat-break-ins

author: coppercone2
author_rank: Super Contributor
timestamp: December 08, 2023, 11:02:14 pm
content: this is a terrible idea

author: Kim Christensen
author_rank: Super Contributor
timestamp: December 08, 2023, 11:11:30 pm
content: Instead of jamming the WiFi, why don't you make a device that intermittently resets or power cycles their WiFi router instead. That would be a lot easier and wouldn't interfere with neighbors or get you in trouble with the local authorities.

author: Whales
author_rank: Super Contributor
timestamp: December 08, 2023, 11:40:00 pm
content: Modern consumer radio protocols (such as those in the many wifi standards) are designed to handle relatively large amounts of interference. They have to be this way because different people using them naturally interfere with each other, and you can't sell a product where only one person in a neighbourhood can use it at a time.There are other Denial Of Service (DOS) attacks against wifi that require only a laptop and won't interfere with the reception of neighbours. Whether or not they will work on your friend is complicated as there are many different versions of wifi and basestation/client implementations with different flaws. Such DOS attacks are considered security flaws, so if you want to find out more then the best information will be available in linux wireless & security communities.

author: radiolistener
author_rank: Super Contributor
timestamp: December 09, 2023, 01:52:02 am
content: I think your circuit won't works for wifi.

author: Simon
author_rank: Unknown
timestamp: December 09, 2023, 11:02:35 am
content: Radio jamming is not really a very good idea. There is electronics, and then there is this mythical thing few understand well enough called RF where if you have not figured already that electronics is simply a programming language for physics, with RF you will learn maybe the hard way that is is the essence of physics. If you have to ask, just don't try it.In my last job I had to roam the shop floor and measure stuff. Tired of being caught in the cross fire of the different radio stations people played at high volume in order to drown out the next persons radio I hatched a plan. I bought one of those FM transmitters that were popular to plug into MP3 players etc to be used in your car to add modern sources to your old radio. All I had to do was tune it to what they were tuned to and the blank signal would drown out the station and mute the radio.I then had quite a bit of fun with one of the welders, he wanted to listen to BBC radio 2, like all BBC stations this is transmitted on 2-4 frequencies at a time, if you are at a point where you can pick up from multiple transmitters you can often get it good twice or more. So this bloke got up and retuned his radio, so I retuned my transmitter, and he retuned his radio, after a few goes ho just turned it off.I had all this fun with an off the shelf item that was legal.As wifi has a protocol to stop collisions it will be harder to coerce existing hardware to do this.

author: Andy Chee
author_rank: Super Contributor
timestamp: December 09, 2023, 11:19:21 am
content: Quote from: Simon on December 09, 2023, 11:02:35 amI wanted to do a similar thing on multiple stations, using a muticast transmitter like those used for emergency broadcast in underground road tunnels (i.e. announcements break-in to your radio, regardless of station).Unfortunately they appear to be less readily available on eBay!

author: TC
author_rank: Contributor
timestamp: December 09, 2023, 01:12:49 pm
content: In the USA jamming isn't a joke. It is illegal.

author: wasedadoc
author_rank: Super Contributor
timestamp: December 09, 2023, 01:34:02 pm
content: The circuit as drawn in the schematic of the opening post doesn't even apply any power to the oscillator.

author: Lambda_
author_rank: Newbie
timestamp: December 09, 2023, 04:48:38 pm
content: Quote from: TC on December 09, 2023, 01:12:49 pmwhy not both...@MarcusFuntWifi is 2,4/5ghzAnd not easily to jamme.If you want to do something like this get Cheap ESP8266 boards.Serch for " raw socket"they can send and overload networks by spamming arp requests or sending deauth packageshttps://github.com/SpacehuhnTech/esp8266_deauther

author: djacobow
author_rank: Super Contributor
timestamp: December 09, 2023, 05:18:20 pm
content: In the US, jamming is illegal but enforcement is joke. The FCC has pretty much thrown in the towel on investigating reports of interference. Unless the interference is widespread, consistent, and, most importantly, pisses off apayinglicensee, you can do whatever you want. In this case, since WiFi is in the ISM band, their likelihood of giving any forks is essentially zero.That is the sad fact.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: December 10, 2023, 12:35:34 am
content: Years ago someone built a jammer for police speed radar. It would insure you were going the speed limit, You set the speed. Someone built one andleft it onwhile going home in his subdivision. He got a big surprise, there was a cop who gave him a ticket because his radar said the fellow was going 70 MPH!!The cop gave him the benefit of the doubt and only ticked him for far less speed, but he did get a ticket!!!True Story.

author: radiolistener
author_rank: Super Contributor
timestamp: December 10, 2023, 06:49:36 pm
content: I tried to play with ADF4351, tune it to wifi channel and connected output to wifi antenna, but wifi still worksIt stops to work when I put generator antenna close to tablet and make a little frequency offset, at some offset it stops to work, but it still able to receive other wifi channels. I tried to do frequency sweep to cover entire channel bandwidth 50-1000 times per second, but it don't works, wifi works ok.ADF4351 has about 0 dBm output (0.001 Watt), I believe it can works better with 2-4 Watts power amplifier, it can just overload nearby wifi receivers, but it requires precise tuning on specific frequency. With using circuit posted on first topic starter post it is almost impossible.There are at least two issues with topic starter circuit:1) no way to tune at specific frequency of wifi channel2) too small output powerAnd it seems that constant carrier is not reliable way to jam wifi channel, there is needs for a more smart patterns.And there are at least two common WiFi bands - 2.4 GHz and 5 GHz. So, even if you jam 2.4 GHz, 5 GHz still can work...

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 10, 2023, 07:00:00 pm
content: There're some jerks at work spending half of their working time looking at the phone (Football matches, bets, Tiktok crap..).As a personal scientific research, would love to jam their 4G signal and see what the animal does when he's forced to work.No shame, I have to make my job, and then part of their's!

author: radiolistener
author_rank: Super Contributor
timestamp: December 10, 2023, 07:08:44 pm
content: You can try to jam 2.4 GHz WiFi with old microwave oven, just power on magnetron with opened door and direct it to WiFi receiver. Microwave oven works at 2.4 GHz band and has pretty high power to completely overload WiFi receivers for all channels... I think it also probably can affect 5 GHz band, because receiver don't have good enough filter, because it needs to receive 2.4 GHz...If WiFi receiver will be too close to microwave oven, it's receiver can be burned out.PS: be very careful with microwave oven experiments, it has high voltage and high power emission, so this can cause serious burns if parts of your body will be on too close distance or can leads to death due to high voltageHere is video with some microwave oven experiments:

author: Whales
author_rank: Super Contributor
timestamp: December 10, 2023, 09:53:16 pm
content: Please don't do that stuff with microwave ovens. They output dangerous quantities of RF if you run them exposed (enough to cause blindness and burns).

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 11, 2023, 12:11:11 am
content: Ahh the Kresoan people, sadly they will die young.

author: coppercone2
author_rank: Super Contributor
timestamp: December 11, 2023, 08:42:37 am
content: they may actually vastly increase their chances of survival by having a wireless jammer, being in Ukraine, if used responsibility, whatever that might be, no idea actually, scary stuff. that seems like mosquito spray in the jurassic era

author: DavidAlfa
author_rank: Super Contributor
timestamp: December 11, 2023, 12:09:05 pm
content: But their "magnificient" magnetron jammer is crap, close to the free energy videos level, well, like most of their videos, lots of these people seem to have some mental issues and strange behaviour.A simple cone antenna can only do so much, so the range was very short, so short that you would need to enter the facilities to cause any effect, at that point, in the one in a million chance enemy didn't see you and consequently shot/nad'ed/shell'ed, you could simply destroy the equipment with a hammer, saving all the effort.Perhabs with a more sotisficated high gain directional design, so the power concentrates on a very sharp beam.

author: AndyBeez
author_rank: Frequent Contributor
timestamp: December 11, 2023, 12:27:13 pm
content: That circuit is a standard tone for tuning the IF cores on old ferrite and wax FM radios, or for testing test equipmentIf you want toprankWIFI, a cost effective method is to Spoof Jam - which is swamping the known WiFi channel with a stronger signal, often from a 1000mW industrial WiFi repeater. Then create a wireless interface that emits the same SSID, BSSID/MAC and security protocol. Client devices will be somewhat confused.Practical? Yes. Funny? Maybe. Legal? Unlikely. Gets your ass kicked by your mates when they discover the evil genius behind the prank?

author: MathWizard
author_rank: Super Contributor
timestamp: December 30, 2023, 07:01:30 am
content: What if you put the phone in the microwave, I bet that's on youtube.When I was younger, I always wanted to make a TV remote control jammer/scrambler, IDK if they still work or if basic remote IR signals have evolved since the 90's.

author: p.larner
author_rank: Frequent Contributor
timestamp: December 30, 2023, 11:21:12 am
content: years ago i noticed everytime i used my microwave oven the wifi dropped connection,on investigation the oven had a hole rotted out under the platter,it went in the bin.