Picture of Radio Jammer
This Item is a Radio Jammer. It sends out EM waves of a certain frequency.

Before you enter:
This item is illegal in certain locations. It is only demonstrating how these items work and what only a few dollars at a electronic store can build.

This also Not a Cell phone jammer. Jamming a Cell phone is similar on its principle, but totally a different build, you need a range from 800MHz to 900MHz. You need an OP amp and a few other parts and formulas

F = 1/(4*R1*C)*(R2/R3)
R3/R2 (noticed it flipped) is the frequency range

850MHz = 1/(4*R1*C)*(1/50MHzS)

You must know the fact that they are illegal in certain areas and MUST NOT rant about it and say they are illegal.
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Step 1: Precausion

This Item May Be Illegal In You Area, Check It Out Before You Build.
I am not Liable for any offenses.

Why This Works:
The Radio Jammer sends out a EM wave at a frequency. The wave is then broadcast throughout an area. Radios will receive this wave (when tuned to that frequency) and It will block the other wave that is broadcast from a station.

So far in my building, I have only been able to block 1 station using one OSCILLATOR.

Have tried adding 1.5v onto a 9v battery. This unexplainably let me listen to another channel on the channel I was blocking.

Step 2: What You Need

Picture of What You Need
What You Need:

An Oscillator, The heart of the Radio Jammer. The frequency you choose will be the frequency you jam. FM radio is in MegaHertz. Example, If you want to block 100.0, then use a 100Mh Oscillator. It may be a bit confusing. I have a 97.7 MHz that says 97M70000 and a 50 MHz that says 50.0000 MHz.

A 9 volt battery

A L.E.D.

An Antenna


An On/Off Switch

A Circuit Board (Optional, but recommended)

Soldering (Used with the Circuit Board)

Price list:
Oscillator: $2.50
9 Volt Battery: found it somewhere, but i think there maybe $1.00
L.E.D.: $0.10
Antenna: $1.00
Wiring: found in workshop, i got a lot for $1.00
On/Off Switch: $1.50
Circuit Board: $0.50
Soldering: $1.00

Total: $8.60
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eddiebee837 months ago

What about Their oscillators seem to range different frequencies, not just one frequency (per oscillator).

Tijil9 months ago

can only one frequency be jammed(blocked) at a time using a single oscillator?

jandmf9 months ago

Will this device work on CB base stations ? If so, what is the range in miles of radios that will be affected ?

eddiebee8310 months ago

Nice thread Barri. I have many questions as Im sure you get.

Could you use the original battery for the phone so you can just charge it over and over as well as the original antenna? (Im thinkin of going with a 125 oscillator.

Also what about spectrum tuners so you can change the frequency? Transko has them.

What type of wiring and why a circuit board, for the on off switch?

Sorry but I'm a complete noob here.

Parth4591 year ago
Parth4591 year ago
this would be great for a old walkie talkie of mine my mom doesnt ever get off her damn phone now i can make her... at least for a while.
TheIguana573 years ago
If I swapped the oscillator with say a 2.4GHz one, i could jam any wireless router or bluetooth headset operating on that frequency right?
That depends on power, frequency, harmonics and carrier. There are a number of factors. Overall if you are pumping enough power into the air on the same frequency or on a harmonic of the same frequency it is likely you could jam the channel. Also for all of you who asked, remember that an oscillator is simply a inductor and capacitor in its more basic form. What I would do is take a look at the construction of basic oscillators, stepper generators and radio jamming during times of war. For all intents most radio jamming is simply producing a signal on the same frequency that you want to jam at a higher power with more noise. AKA if you are trying to block a voice signal a good way to do it would be to copy several voices on a tape and send that as a signal.
Or just a really loud version of Never Gonna give you up by Rick Astley.
You might like to see this link, before you think about building jamming circuits.
srgntpwny1 year ago
if i put a 2.4 GHz oscillator in this would it block a 3g connection i would be in a situation where im using 4 AAA batteries
markee23 years ago
Nice instructables but oscillator is kinda hard to find. I got circuit here claims that can do the same... radio jammer, dont know what is the idea behind in this circuit. Anyone have idea if it is working or it will be working. circuit copied from:

fm jammer circuit.jpg
Oscillators aren't to hard to find but if you don't own one, like me this is an excellent circuit!!!!!!!!
I live in a place where it is illegal to use such things. The schematic look really strait forward and simple. I dont know if it would work but I am working on a Faraday cage so I can test such things legally
Da-Nargh3 years ago
Mr Barri-Kid, I thank you for teaching me how to eviscerate unwanted radio stations at work
Hello Da-Nargh,

I cannot locate any Oscillators as described here, can you point me in the right direction?

Your help or anyone's would be greatly appreciated.'

I need Mhz around the 107.6
barri_kid (author)  mattjoy3 years ago
I got mine at an electronic surplus store. radio shack may work. I don't know where you are though
Hi Barri_kid,

Sorry for my limited info, i am in Australia. The main electronic stores do not supply oscillators of this type. 4 pin... and none of the frequencies I need in my country.

or at least I cannot find them.. perhaps you can point me to an on-line store that supplies oscillators?

barri_kid (author)  mattjoy3 years ago
This may be useful

Usually I don't buy online, so I don't know if its good. I think I have heard of Newarc, or it may have been Newegg.
Hi Barri_kid,
thank you.. that links seems to have similar Oscillators..
Thank you for your help.
What frequency osc would I need to jam 660 AM?
WFAN sports radio. Co-workers blasts it all day!!
You would need a 660 megahertz oscillator
Joebo3 years ago
Good article. This is pretty strange that increasing the 9v battery by 1.5v let you eavesdrop on the channel your were blocking. try readjusting slightly and checking out what else happens... Please let us know. Thanks.
static3 years ago
After reading the instructable, and the comments, I really don't know what to make of it all
My ? is can u make it to block wifi signals. I totally understand everything you are doing, and how it works.
64bithero3 years ago
Where did you purchase your antenna?
I can't find anywhere selling them for less than $10 =\
does this block FM or AM??? Or both??!!!!
thepaul934 years ago
Will a 100Mhz oscillator only block 100Mhz. Or can it span out to 90-108Mhz?
barri_kid (author)  thepaul934 years ago
There is probably some tolerance to each oscillator. I can't say for certain that it will go from 90-108, but it probably will do +- 1Mhz. I haven't checked it out in a long time, so I don't really know if its +-1Mhz or larger.
So does that mean that this jammer will only block 100Mhz?
barri_kid (author)  thepaul934 years ago
In a short answer, it will block around maybe 98-102. There is no way to make it have a larger area by changing something electronically, at least to my knowledge.
Then i need to get myself one of these.
bobryk4 years ago
you can add a switch to route the current from the battery to another oscillator of a different frequency to have more than one choice. my family listens to lots of boring stations ; )
Bardouv4 years ago
would there be anyway to use an old stereo instead of phone? so that you'd be able to 'tune into' the station you were trying to block instead of just blocking one station.
barri_kid (author)  Bardouv4 years ago
Stereos are just a receiver, they don't do any transmitting. I understand what you are getting at, where if you want to block some channel you would just turn a knob to get to the certain frequency, but in order to change the frequency, you would need to change the oscillators frequency, which to my understanding would be to shorten or lengthen the crystal inside (which I don't think is going to happen).
ferguse4 years ago
where would you get an oscillator?
radio shack
arihant4 years ago
why you use a led???
so you know when its on
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