555 Timer IC Tutorials

Cell Phone Signal Jammer Circuit using 555 Timer IC

Cell Phone Signal Jammer Project Description:


Cell Phone Signal Jammer using 555 Timer IC– In this tutorial, you will learn how to make your own low-cost Cell Phone Signal Jammer using the NE555 Timer IC and some other electronic components.  This is only for educational purposes and that’s the reason this Cell Phone Signal Jammer has a small range.

Before you start building this project make sure you have the basic knowledge about the 555 Timer IC, Transistors, Capacitors, and Resistors.


In most places actively blocking any kind of communications is illegal. So if you plan on using this circuit make sure you check your local Laws and Regulations. This DIY Cell Phone Signal Jammer Project is only for the Educational Purposes.

Amazon Purchase Links:

Super Starter kit for Beginners

Variable Supply:

Digital Multimeter:

PCB small portable drill machine:

*Please Note: These are affiliate links. I may make a commission if you buy the components through these links. I would appreciate your support in this way!

What is a Cell Phone Signal Jammer?

A mobile phone jammer or blocker is a device which deliberately transmits signals on the same radio frequencies as mobile phones, disrupting the communication between the phone and the cell-phone base station, effectively disabling mobile phones within the range of the jammer, preventing them from receiving signals and from transmitting them. Jammers can be used in practically any location, but are found primarily in places where a phone call would be particularly disruptive because silence is expected, such as entertainment venues.

Because they disrupt the operations of legitimate mobile phone services, the use of such blocking devices is illegal in many jurisdictions, especially without a licence. When operational, such devices also block access to emergency services.


Since these jammers actively broadcast radio signals, they may or may not be legal to possess or operate based on the specific laws of the area one is in.

United States:

 Cell phone blocking devices are used by federal officials under certain circumstances. Privacy rights of property owners may affect the policy and application of law within buildings. For radio communications, it is illegal to operate, manufacture, import, or offer for sale (including advertising) (Communications Act of 1934). Blocking radio communications in public can carry fines of up to $112,000 and/or imprisonment of up to one year. The Homeland Security Act of 2002 may override the Communications Act of 1934.


Illegal to use without permission. The individuals or institutions must get No Objection Certificates (NOCs) before installation of such devices.

United Kingdom:

Illegal to use, but legal to own. Having been proposed by prison inspectors, installation and use in jails has been legal since the end of 2012.


Illegal to operate, supply, or possess unless the user has a PMTS C telecommunications licence under the Radiocommunications (Interpretation) Determination 2000.


Illegal, but installation in jails has been proposed.


Illegal under sections 4, 9, and 10 of the Radiocommunication Act, except by federal law-enforcement agencies who have obtained approval.


Illegal, according to the European Commission’s “Interpretation of the Directive 1999/5/EC”.


Legal until 2012 in movie theaters, concert halls and places with performances, but illegal since 2012.


Illegal by law except for security and military agencies, and usage in jail, theatres, mosques, schools etc. with prior permit and jamming strictly limited to the firm perimeter with zero leakage.


Illegal to use without permits.




Illegal both to own and use, according to the Penal Code offenders are punished with imprisonment up to four years. Can be used under strict authorization in exceptional cases by Italian law enforcement agencies, such as Polizia Di Stato and Carabinieri.

New Zealand:

Illegal to sell, manufacture, or use. Legal inside jails by Department of Corrections.


Illegal to manufacture, import, use or sell radio jamming equipment other than by or for supply to a permitted person.

South Africa:

Illegal. No organisation is allowed to jam cellular signals, and any device which is used to jam signals is illegal.


Illegal. Legal inside jails, prisons, and for military use.


Legal, planned to be used in schools.

Components needed for the Cell Phone Signal Jammer:

NE555 Timer IC

BF495 Transistor

2PF Ceramic Capacitor

4.7PF Ceramic Capacitor

3.3PF Ceramic Capacitor

47PF Ceramic Capacitor

30PF Variable / Trimmer Capacitor

1uF 63V Electrolytic Capacitor

10K Resistor

6.8K Resistor

82K Resistor

220E Resistor

5.6K Resistor

24 AWG Copper Wire

3 Pin Mini Slide Switch (SPDT)

3mm LED (Green)

2Pin Male Header Connector

9V Battery Connector

9V Battery

Cell Phone Signal Jammer Circuit Diagram:

Cell Phone Signal Jammer

Cell Phone Jammer Circuit Explanation

If you know about the 555 Timer IC and how to use it then I don’t think so it would be difficult for you to understand. For any signal jammer circuit, there are three main parts in the circuit and when combined together the output of that circuit will work as a jammer. These three main circuit parts are

RF amplifier.

Voltage controlled oscillator.

Tuning circuit.

The entire cell phone signal jammer circuit can be powered up using a 9V battery. The Switch S1 is used to turn ON and turn OFF the cell phone jammer. In the above circuit the 555 Timer is used as the Frequency generator. The output of the 555 timer is fed to the amplifier circuit through a 1uf electrolytic capacitor. This capacitor blocks the dc and allow the AC signal to pass which is amplified by the Transistor Q1. The amplified signal is then given to the antenna through a 4.7pF capacitor.

Cell Phone Signal Jammer PCB board:

Cell Phone Signal Jammer

Components Placement “Silkscreen”:

Cell Phone Signal Jammer

Cell Phone Jammer Making:

First Coil-  4 turns 5mm of 24 AWG wire. I used a screw driver of making this coil.

Cell Phone Signal Jammer

Second Coil- 3 turns 5mm of 24 AWG wire.

Cell Phone Signal Jammer

Third Coil- 15 turns 5mm of 24 AWG wire.

Cell Phone Signal Jammer

Cell phone Jammer PCB board:

For the PCB design transferring, Etching, and Drilling watch my video tutorial.

Cell Phone Signal Jammer

After fixing all the electronic components, finally, I completed the soldering. I doubled checked all my connections using a digital Multimeter, and luckily there were no solder bridges.

Cell Phone Signal Jammer

Cell Phone Jammer Final Look:

Cell Phone Signal Jammer

The final step was to connect the 9V battery connector. I used a 9V battery for powering the circuit.

Cell Phone Signal Jammer

When I placed the cell phone next to the cell phone jammer the mobile phone signal was successfully jammed. I don’t claim that this is the best cell phone jammer ever built, but for the beginners this is just fine. You can play around with the values of resistors and capacitors to increase the range. Because the one we just built has small range.


Engr Fahad

My name is Shahzada Fahad and I am an Electrical Engineer. I have been doing Job in UAE as a site engineer in an Electrical Construction Company. Currently, I am running my own YouTube channel "Electronic Clinic", and managing this Website. My Hobbies are * Watching Movies * Music * Martial Arts * Photography * Travelling * Make Sketches and so on...


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