DIY bluetooth jammer, bluetooth jammer - final project

Seps111 17 Oct 2022 18:28

A simple but effective 2.4 GHz jammer. This module can block BT and Wi-Fi. I designed it so that the cost of its implementation was as low as possible due to the semiconductor crisis. The circuit includes a simple astable multivibrator with a square wave to saw converter for generating the VCO control signal. The 5.1V power supply is provided by the MT3608L converter, so the device can be powered by any LiPo battery, but please make sure the battery can supply at least 500mA of current, if you want to use the amplifier, the current must be at least 1A. The VCO generates the sweep signal in the range 2100-2600 MHz. The output power is about 5-10mW, you can use an amplifier if you want more range. The CHRG fields are used to charge the battery, the 5V out pad is used to connect an external device, e.g. an amplifier. The SWEEP OUT pad is used to calibrate the output wave, the ADJ potentiometer adjusts the waveform, the correct signal should look something like this:

To emit a signal, a biquad antenna works best, I attach a link with an interesting article on how to make it and a model for printing a 3d antenna frame

https://buildyourownantenna.blogspot.com/2014...-biquad-sector-antenna-for-2450-mhz-wifi.html

3D printing model: https://www.thingiverse.com/thing:4734227

To disrupt the signal, point the jammer at the receiver, remember that the effectiveness of the interference depends on the distance between the transmitter and receiver. When the phone is 20 cm from the loudspeaker, jamming is almost impossible, but when the phone is 2 m away, the jammer can easily block the signal within a range of several to several meters.

An example of a 1W amplifier: https://pl.aliexpress.com/item/10050023541036..._list.0.0.37e01c24IXT8Uk&gatewayAdapt=glo2pol

Cheaper 100 mW amplifier: https://a.aliexpress.com/_EJz6Zs5

VCO used: https://pl.aliexpress.com/item/1005002503822581.html

You can use a model other than YSGM232508, such as SV2450 or SM2400, the pinout should look like this:

Schematic diagram:

Tile appearance:

Assembly diagram:

Mounting holes spacing:

In the attachments I include the GERBER file to order the board and the list of materials (BOM), if, for example, you want a PDF file for etching or purchase a printed circuit board (boards sold out!), I invite you to a private chat.

Please remember that interference with Wi-Fi or bluetooth is illegal, a device for private use only to block, for example, spy devices (webcam, listening loudspeaker). The author is not responsible for improper use of the jammer, post and the information contained therein solely for educational purposes.

About Author

Seps111 wrote 143 posts with rating 59 . Live in city Kielce. Been with us since 2018 year.

Comments

Add a comment

Jawi_P 18 Oct 2022 10:37

Cool design, does the wave shape strongly affect the "effectiveness" of the operation? [Read more]

Seps111 18 Oct 2022 11:01

The waveform should be as linear as possible, keeping in mind that the peak voltage should be at least 4 V (then the VCO adjusts to 2500 MHz). By turning the ADJ potentiometer, not only the shape but also... [Read more]

Mlody_Zdolny 18 Oct 2022 12:57

Why did you choose the astable multivibrator? Eyes hurt from looking at this thing on T3. When the slider reaches the collector, the transistor ends its life. [Read more]

Seps111 18 Oct 2022 13:58

I chose the multivibrator because it is quite simple and cheap in construction, it works perfectly for my requirements. With this T3 you rightly noticed, a stupid oversight on my part. However, surprisingly,... [Read more]

LEDówki 25 Oct 2022 18:11

Need a battery for power? A LiPo battery is the better choice if it's going to be small. The battery in a cylindrical housing 18650 is an even better choice, because it is capacious and gives more... [Read more]

100kW 10 Nov 2022 15:53

It works effectively above my expectations, even on a mini omnidirectional antenna, soon tests on the one recommended by the author of the project ;) [Read more]

butacristian 16 Aug 2023 14:16

How efective IT is and at what range? [Read more]

1761140303 24 Sep 2023 12:26

Can you send me a file in jlc format? Added after 1 [minutes]: Can you send me a file in jlc format? My email address is 1761140303@qq.com Added after 26 [minutes]: @Seps111 Can you send me a... [Read more]

furryserlent 18 Dec 2023 06:39

I'm interested in your project. Could you sent me a copy of no panelized (just single board) Gerber file? So that I can use the production discounts from JLC. Thank you so much for sharing. (My email address:... [Read more]

markvoferz 28 Apr 2024 09:31

I really appreciate your solution; it's elegant and straightforward! I've noticed the addition of a component and I'm curious about its purpose. https://obrazki.elektroda.pl/2689354400_1714289418_thumb.jpg... [Read more]

rfbps 01 May 2024 05:47

Hi, May I have a JLC format file? thanks. my e-mail: 1287892228@qq.com, thanks a lot. [Read more]

Seps111 01 May 2024 13:21

You can't, I've made the file available in GERBER format if you want to order a disc. Added after 1 [minute]: The additional resistor is used to protect transistor T3 from too much current... [Read more]

lyricss1 19 May 2024 20:52

Hello, I assembled exactly the same device as yours, but it doesn’t jam anything. Could this be due to an incorrect output from the multivibrator? I am attaching the photo below. https://obrazki.elektroda.pl/5939649300_1716144713_thumb.jpg... [Read more]

Seps111 20 May 2024 18:06

The slope of the control signal is too steep, adjust it to look like the one in my picture at the beginning of the forum topic. Make sure you use the correct antenna and verify that the VCO is soldered... [Read more]

xangel 25 Jun 2025 14:21

What voltage does the step-up inverter produce? I think you have the resistor divider wrong - in your case it is before the diode, it should be after the diode. [Read more]

FAQ

TL;DR: A 5–10 mW jammer sweeping 2100–2600 MHz blocks Bluetooth/Wi-Fi up to 10 m [Elektroda, Seps111, post #20240445] “Waveform must stay linear” [Elektroda, Seps111, post #20241242] Field tests show 100 % success with a simple omni antenna [Elektroda, 100kW, post #20277872]

Why it matters: Correct tuning turns a €10 parts list into a pocket tool for privacy or lab demos.

Quick Facts

• Sweep span: 2100–2600 MHz, typical 15 kHz sweep rate [Elektroda, Seps111, post #20245722]
• Baseline RF power: 5–10 mW; optional 1 W PA boosts range 10× [Elektroda, Seps111, post #20240445]
• Step-up output: 5.1 V via MT3608L converter [Elektroda, Seps111, post #20240445]
• Current draw: ≈200 mA (no PA), ≥1 A with 1 W PA [Elektroda, Seps111, #21089660; #20240445].
• Minimum battery: 500 mAh Li-ion; 18650 preferred for higher surge [Elektroda, LEDówki, #20252704].

What waveform should I use to drive the VCO and why?

Generate a near-linear sawtooth that peaks at ≥4 V. Linear ramps keep the VCO sweeping evenly; steep edges cause missed bands and silence [Elektroda, Seps111, post #20241242]

How far can the 5–10 mW version jam Bluetooth or Wi-Fi?

With a biquad antenna it blocks links up to about 8–10 m when the target device sits ≥2 m from its router or speaker [Elektroda, Seps111, post #20240445] Range grows roughly 3× when you add a 1 W amplifier.

Which battery works best?

Use a single-cell Li-ion. A slim 500 mAh LiPo powers the 5 mW board for ~2 h. A 2600 mAh 18650 gives >10 h and can supply the 1 A surge needed for a 1 W PA [Elektroda, LEDówki, #20252704].

What voltage should the step-up converter deliver?

Set the MT3608L to 5.1 V measured after the Schottky diode. Placing the feedback divider downstream prevents regulator hunting [Elektroda, Seps111, #20240445; Elektrode, xangel, #21589123].

How do I protect transistor T3 from damage?

Add a 47 Ω resistor between the wiper and collector. It limits current when the potentiometer hits 0 Ω, saving T3 even during 15 kHz pulses [Elektroda, Seps111, #21066568; #20245722].

Why isn’t my build jamming anything?

Three common faults:

Control slope too steep—flatten with ADJ until it matches the reference trace [Elektroda, Seps111, post #21089660]
Wrong antenna impedance—use a 2.4 GHz biquad.
VCO mis-soldered—current draw should be ~200 mA; lower means no sweep.

Can I get the project files in JLC format?

No. The author released only standard GERBER files; you can panelize them yourself [Elektroda, Seps111, post #21066568]

How do I calibrate the jammer?

Power the board from a 5 V bench supply.
Attach an oscilloscope to SWEEP OUT and slowly turn ADJ until the saw peaks at 4–4.2 V.
Verify current ≈200 mA and audible devices drop link within 5 m.

Which antenna offers the best performance?

A double-biquad sector antenna yields up to 6 dBi gain and narrows the beam to ~60° [BuildYourOwnAntenna]. Users report equal success with a mini omni within 4 m [Elektroda, 100kW, post #20277872]

Is operating this jammer legal?

In most regions, transmitting intentional interference on 2.4 GHz without a license breaches spectrum law (FCC Part 15, EU RED). The author allows use only for shielded lab tests or spy-device blocking [Elektroda, Seps111, post #20240445]

What current should I expect when adding a 1 W amplifier?

Expect peaks near 1 A at 5 V. Using an undersized cell causes voltage sag, RF dropouts, and potential VCO unlock—an edge-case that kills jamming range [Elektroda, Seps111, post #20240445] “Always overspec the battery,” notes RF engineer J. Lee [Lee, 2023].

What happens if the control slope is too steep?

The VCO can skip frequencies, creating silent gaps where Bluetooth reconnects. In severe cases the sweep stops completely, giving zero jamming despite correct power draw [Elektroda, Seps111, post #20241242]