The post describes a simple homemade RF signal jammer circuit that can be used for jamming any RF signal within a radial range of 10 meters. The idea was requested by one of the interested readers of this blog.
Technical Specifications
I am not a large business interest, but am in need of a circuit which would not only help me, but eventually be welcomed by just about everyone now alive.
I am in need of a circuit which will jam RFsignals. I realize jammers are illegal when they disrupt cellphone communication and commercial enterprise. I am only looking to jam (1.) remotely controlled harassment devices and (2.) spyware within the confines of my property. Jamming range limited to around a 25' x 25' area.
There is a growing community of victims of electronic harassment. We all experience an invasion of our personal lives/finances and private conversations, and are sometimes physically stalked and attacked.
Due to the nature of electronic harassment, it will take time for justice and protection to catch up and solve the problem. As for electronics, some circuits to control the misuse of flux & solder are long overdue in the marketplace.
Up until now, most of the interest has been placed on projects of invasion and abuse, such as those contained on many different website
I am not overly skilled in electronics, and only come to it in self defense. I am self taught and can follow a schematic and complete a project, and am slowly gaining understanding of the underlying theory.
Please advise regarding your interest to help, and your financial requirements. I look forward to hearing from you.
Circuit Diagram
Introduction
A simple looking RF signal jammer circuit can be seen in the above diagram, which may be capable of jamming all sorts RF signal within the range of 5 to 10 meters.
The circuit can be made suitable with any desired frequency to be jammed by merely using different sets of L1/L2 and by tweaking the 22pF trimmers accordingly.
The frequency that could be jammed using this circuit could be well in the range of 50 MHz to 1Ghz, however making it compatible with frequencies above 500 MHz could get much complex and parameters much critical owing to the fact that higher frequencies require shorter interconnections and may involve other stability issues.
The present design can be used for jamming FM radio stations situated in the within 40 meters radial distance or even higher.
The circuity of the proposed RF signal jammer is basically made of two distinct stages:
RF Circuit Stages
The one comprising T1 and the associated parts form the RF oscillator stage while the other stage consisting of T2 and the complementing parts for amplifying and transmitting the low voltage oscillations from T1 into the air.
The above strong RF carrier signals transmitted by T2 may be appropriately modulated with any external frequency such as an audio or speech by feeding the signal across the terminal indicated "Test".
The circuit is highly stable and doesn't falter with varying input supply voltages due to the presence of the 78L05 voltage regulator at the base of T1 which clamps the base of T1 with a constant biasing current making sure that the oscillations created by the T1 stage stays very stable and consistent.
The above feature is perfectly complemented by the T2 stage which accepts the oscillations from the T1 stage and amplifies and transforms the signals with much higher current so that the signals are able to travel across larger radial distances in the air.
However in order to implement an optimal transmission of the signals, 50 OHM impedance antenna must be used with the output of the circuit.
This could be any ordinary aluminum dipole yagi antenna. A simple flexible wire measuring about a meter would also do but would reduce the transmission strength by about 60 % making the unit much inefficient as far as the transmission range is concerned.
How to Peak the Resonance
The performance of the RF jammer could be highly improved by adjusting the presets to produce peak resonance. This can be done with the following points:
- Connect a 0 - 10V DC voltmeter across the point "test" and the ground line.
- Adjust the right side 22p trimmer such that the meter reads around a maximum of 3V on the meter.
- This might disturb the initial frequency of the system that you might have set for the jamming purpose.
- So go back to the left side 22p trimmer and fine tune it again to set the desired frequency back into place.
Your peak resonance for the circuit is set now, and you can expect maximum efficiency from it.
RF Jammer Coil Specifications
For making the RF jammer compatible with other frequencies, the coil L1 and L2 must be shortened in terms of their number of turns and/or also the diameter...this will need some experimentation until the right frequency is determined.
The adjoining trimmers may also tweaked for getting an optimal response from the jammer circuit or until a perfect jamming is achieved through the circuit.
A good quality, well designed PCB is strictly recommended for constructing the RF jammer circuit
For jamming standard FM broadcasts within a range of 50 meters, L1 and L2 may be built as indicated in the following images:
PCB Etched RF Coil
The above image shows the construction L2 using a 7 turn, 1mm super enameled copper wire with a diameter of approximately 5 to 6mm (internal)....see how the tap is extracted from the relevant end of the coil.
The following image shows how L1 can be designed by etching the tracks on the PCB itself or the same could be built using pieces of diode leads as explained in this FM wireless MIC circuit
Parts List
TR1 = BC547
TR2 = 2N2369
rest are furnished in the diagram.
How to increase the range of the jammer
Would it be possible to tune it to the 125-135 kHz range ?
yes, by using larger value for the 22pF trimmer
I was wondering, if by using a 555 or some other IC one could simplify the circuit. Furthermore, in my case I would like to selectively focus on a specific frequency range, could that perhaps be used to simplify it further ?
Transistors are better suited for high frequency switching and transmission, so I don’t think IC 555 will be appropriate for this application.
Swag
I am a X-Wife of a genuine intelligent manipulative Criminal that has made his way into my Home while having Major Surgery, & had placed what appears to be a Spy Listening Device in the South side of my Kitchen. My Son mistakenly allowed him in the House. This Device has excellent back feed Reception that appears to go directly to him. I can always tell when he has came home because the Home Noises start to occur. I want to completely Block this Man forever. He is currently under Criminal Investigation for attempted Arson, & Theft of X 2 Boats & a Pop Up Camper. I honestly beleive he wants any Heads Up that may prevent his apprehension by Law Enforcement. I have not spent Money on a Jammer Device due to the uncertainty that it would work to Block the Sound transmission to & fro. What is your recommendation? I was told by an Electrician that Magnets would skew the Device, but, thus far, these Magnets do not appear to have done the Job. I would appreciate any helpful guidance for how to begin to tackle this resistant X-Husband. Thanks, Maureen L. Walker
Hi Maureen,
I assume the frequency of the device is in the lower Mhz FM range. If it is so then the above circuit can be effectively customized to jam the device.
But the challenge is to first know the frequency of the device, which can be a difficult thing to do. Once the frequency is known it can be blocked using the above explained jammer circuit!
Another option would be to trace and locate the device and then simply destroy it manually. The tracing could be done through the following circuit. One has to build it and start scanning the walls and other intricate places until the LED lights up indicating the possible location of the bug
https://www.homemade-circuits.com/bug-detector-circuit-rf-sniffer-circuit/
You are getting sound from it? It isn’t a very good device. Fact: A cheap device that is there long term must be powered from an electrical circuit nearby. Find the circuit breaker for that area, and shut it off. Have someone with really good hearing listen in the area while you turn the breaker on and off (probably every couple minutes as it will work off of a power supply and take time to discharge). The device may well make noise as it powers on and off. If not, have someone check the nearby outlets for added wires. A small device wire will be much smaller than regular house wiring.
Dear,
I need to interfere with a GPS tracker that I install my boss in my car.
Please, could you tell me how to modify this circuit to reach the 1.5 Ghz frequency?
Regards,
sorry I don’t know how to do it….
I need to jam frequency from 0-30 MHz, on 5,9,16,20,24,28 MHz. Can I do this according this link http://www.instructables.com/id/RF-Jammer/step5/Future-modificationsenhancements/ , what electronic parts "determines" max. output that jammer can offer.
Tnaks for answer, Robin.
according to the specifications of the circuit in the article it may be possible to jam those frequencies…but I cannot suggest about the parts or method, because it haven't studied the article completely..
kindly help which transistors T1 and T2 to be used and turns of coils in both inductance which I was unable to find in above description
I'll upadte the info soon in the article itself.
Sir, We have 10 different frequencies used by cellphone providers in sweden. Does it mean that I have to build 10 different jammers to be sure that no traffic can pass? Thanks in advance
Asbjorn, all the mobiles will be jammed together which are within the range of the jammer frequency…using a single jammer circuit
yes i know that.. i olready had one circuit but there battery drainage occurs mostly and signal strength was bit slow….. swagatam in the above circuit whats the value of inductors L1 and L2??
Aqib, the values were not measured, I only have the turn data, both the coils are 5 turns, 5mm diameter using 0.8mm super enameled copper wire
swagatam thanks for this circuit… but i just want to know can i buy these parts online ?… as trimmers and inductors are not avalaible here…. or can i buy these parts from you ?
Aqib, yes you can get everything mentioned above from any reputed online electronic store.
However please note that converting the above jammer design to a GHz range could be an extremely complex job, please proceed only if you are entirely sure about the concept and the outcomes.