Privacy Shield: The Ultimate Low-Cost Gadget to Find Hidden Cameras in Any Rental (ESP32 Project)

By CyberDudeBivash • September 28, 2025, 2:05 AM IST • DIY Tech & Privacy Guide

You’ve just checked into your Airbnb for a weekend getaway. The place looks great, but a nagging thought enters your mind: “Is someone watching?” It’s a chilling question, but in 2025, it’s a necessary one. The news is filled with horror stories of hidden cameras found in rental homes, hotel rooms, and changing rooms. Relying on just your eyes to find a camera lens the size of a pinhole is a losing game. Professional camera detectors can cost a fortune, but what if I told you that you could build your own powerful, dual-mode hidden camera detector for less than the cost of a pizza? Welcome to the **Privacy Shield** project. This is your complete, step-by-step guide to building a simple, low-cost, and highly effective gadget using a common ESP32 microcontroller. It’s the perfect weekend project to take back control of your privacy and give you peace of mind wherever you go.

Disclosure: This is a DIY project guide for educational purposes. It contains affiliate links to electronic components and other useful services. Your purchases through these links help support more projects like this!

The Complete Traveler’s Security Kit

Physical privacy is just one piece of the puzzle. Secure your entire trip with these essentials.

Project Components (AliExpress WW): Get all the affordable electronic components for this project—like the ESP32, LEDs, and wires—from a global marketplace.
Digital Privacy (TurboVPN): A must-have for any traveler. Use it to encrypt your internet connection on the rental’s Wi-Fi, protecting your data from snoops.
Device Security (Kaspersky): Protect your laptop and phone from malware that could be present on untrusted rental networks.
Secure Bookings & Payments (Tata Neu Super App): Manage your travel bookings and payments securely through a trusted, all-in-one app.

DIY Project Guide: Table of Contents

Chapter 1: The Science – How Hidden Camera Detectors Work

Our Privacy Shield is not magic; it’s based on two proven scientific principles for detecting hidden cameras.

Method 1: Detecting Lens Glint (Optical Detection)

Every camera, no matter how tiny, needs a lens. A lens is a piece of curved glass or plastic designed to focus light. This property also means it reflects light in a very specific and predictable way, a phenomenon called **retro-reflection**.

Our device uses a ring of ultra-bright red LEDs. When you shine this light around a room and look through a viewfinder, any camera lens in the light’s path will reflect a bright, sharp pinpoint of red light directly back at you. This “lens glint” is distinct from the duller reflections from other surfaces. It allows you to spot a lens hidden in everyday objects like a smoke detector, a digital clock, a USB charger, or even a picture frame.

Method 2: Detecting Wireless Signals (RF Detection)

Most modern spy cameras are wireless. They need to transmit their video feed to a receiver, and they almost always do this using a standard 2.4 GHz Wi-Fi signal.

Our device uses the powerful Wi-Fi radio on the ESP32 microcontroller to act as a passive scanner. It constantly sweeps the airwaves, listening for all nearby Wi-Fi networks. Hidden cameras often betray themselves in one of two ways:

They create their own, easily identifiable open Wi-Fi network for initial setup, often with a name containing “IPC” (Internet Protocol Camera) or a long, random string of characters.
They connect to the main rental Wi-Fi, but their constant broadcasting can be detected as an unusual, high-traffic client on the network.

By combining both optical and RF detection, our Privacy Shield gives you two powerful ways to uncover hidden surveillance.

Chapter 2: Building the Privacy Shield – A Step-by-Step Guide

Ready to build? This project is perfect for beginners. Let’s get started.

Part 1: The Shopping List (Components)

You can get all of these components for just a few hundred rupees. They are all commonly available from electronics suppliers.

**The Brain:** 1 x ESP32 Development Board (any model like the WROOM-32 will work perfectly).
**The Eyes:** 6-8 x Ultra-bright Red LEDs (5mm).
**The Power:** 1 x 3.7V LiPo Battery and a compatible TP4056 LiPo charging board. Alternatively, you can use a simple USB power bank.
**The Controls:** 1 x Small slide switch.

Pro Tip: The easiest and cheapest way to source all these parts is from a large global marketplace. You can find dozens of sellers offering ESP32 kits and all the other components on AliExpress WW.

Part 2: The Assembly (Wiring)

The wiring for the LED part of the circuit is very simple. We will wire all the LEDs in parallel to one of the GPIO (General Purpose Input/Output) pins on the ESP32, with a switch to turn them on and off.

[Simple wiring diagram image showing the ESP32, a switch, and the parallel LEDs connected to a GPIO pin and Ground]

Connect the positive (long) legs of all your LEDs together.
Connect the negative (short) legs of all your LEDs together.
Connect the ESP32’s `GND` (Ground) pin to the common negative legs of the LEDs.
Connect one of the ESP32’s GPIO pins (e.g., `D2`) to one terminal of your slide switch.
Connect the other terminal of the slide switch to the common positive legs of the LEDs.
Power the ESP32 via its USB port from your power bank or the LiPo battery module.

Part 3: The Code (Programming the ESP32)

We’ll use the free Arduino IDE to program our ESP32. The code has two functions: it blinks the LEDs for the optical scan and it continuously scans for Wi-Fi networks.

Setup your Arduino IDE: You’ll need to add the ESP32 board manager to your Arduino IDE. You can find many easy tutorials online for how to do this.

The Code:** Copy and paste the following code into a new sketch in the Arduino IDE, then upload it to your ESP32 board.

#include "WiFi.h"

// Define the pin the LEDs are connected to
const int ledPin = 2;

void setup() {
  Serial.begin(115200);
  pinMode(ledPin, OUTPUT);

  // Set WiFi to station mode and disconnect from an AP if it was previously connected
  WiFi.mode(WIFI_STA);
  WiFi.disconnect();
  delay(100);

  Serial.println("Setup done. Privacy Shield is active.");
  Serial.println("Scanning for Wi-Fi networks...");
}

void loop() {
  // Blink the LEDs for the optical scan
  digitalWrite(ledPin, HIGH);
  delay(150);
  digitalWrite(ledPin, LOW);
  delay(150);

  // Scan for Wi-Fi networks in the background
  int n = WiFi.scanNetworks();
  Serial.println("Scan complete.");
  if (n == 0) {
      Serial.println("No networks found.");
  } else {
    Serial.print(n);
    Serial.println(" networks found:");
    for (int i = 0; i < n; ++i) {
      // Print SSID and RSSI for each network found
      Serial.print(i + 1);
      Serial.print(": ");
      Serial.print(WiFi.SSID(i));
      Serial.print(" (");
      Serial.print(WiFi.RSSI(i));
      Serial.print(")");
      Serial.println((WiFi.encryptionType(i) == WIFI_AUTH_OPEN) ? " - OPEN" : "");
      delay(10);
    }
  }
  Serial.println("");

  // Wait 5 seconds before scanning again
  delay(5000);
}

Part 4: The Case (Putting It All Together)

Once everything is wired and programmed, place it in your project box. Cut a hole for the switch and a small hole to use as a “viewfinder” in the center of the LED ring. The LEDs should be facing out. Now your Privacy Shield is complete!

Chapter 3: The Hunt – How to Use Your Privacy Shield to Sweep a Room

Now for the fun part. You’ve checked into your room. Here’s your sweep methodology.

Step 1: The Optical Sweep (Lens Glint)

Turn off all the lights in the room. The darker, the better.
Power on your Privacy Shield. The red LEDs should start pulsing.
Hold the device up to your eye and look through the viewfinder hole.
Slowly and methodically scan the entire room. Pay extremely close attention to common hiding spots:
- Smoke detectors
- Digital clocks and alarm clocks
- USB wall chargers and power strips
- Picture frames, mirrors, and wall decor
- Indoor plants, speakers, and TVs
- Any small, unexplained holes in walls or furniture
Look for a bright, distinct pinpoint of red light reflecting back at you. If you see one, you have likely found a camera lens. Investigate it closely.

Step 2: The RF Sweep (Wi-Fi Scan)

Connect your Privacy Shield to your laptop via USB.
Open the Serial Monitor in the Arduino IDE (set the baud rate to 115200).
The device will automatically start scanning for and listing all nearby Wi-Fi networks every few seconds.
Look for suspicious networks. Red flags include:
- Networks with strange, long, random names (e.g., `A9-D4-C2-F1-8B-3A`).
- Networks that are “OPEN” (unsecured).
- Networks that have a very strong signal strength (RSSI close to 0) but don’t belong to the main hotel/rental Wi-Fi.

If you find a suspicious network, you can use a Wi-Fi analyzer app on your phone to try and pinpoint its physical location by walking around the room and watching the signal strength.

Chapter 4: Beyond the Gadget – Your Full Digital Self-Defense Plan

The Privacy Shield protects your physical space, but you must also protect your digital space when you travel.

Use a VPN. Always. The Wi-Fi in your rental is an untrusted network. The owner or other guests could potentially snoop on your traffic. A VPN is non-negotiable. A simple, one-click app like TurboVPN will encrypt all your internet traffic, making it completely private.

Chapter 5: Extended FAQ for DIY Privacy Enthusiasts

Q: Why use an ESP32 instead of a simpler microcontroller?
A: The ESP32 is the perfect choice because it’s not just a microcontroller; it has a built-in, powerful Wi-Fi and Bluetooth radio. This allows us to create a dual-mode detector (optical and RF) with a single, low-cost board.

Q: Could I add a screen to this project?
A: Absolutely! This is a great next step. You could add a small OLED screen (like an SSD1306) to the project and modify the code to display the Wi-Fi scan results directly on the device, making it fully portable without needing a laptop.

Q: I love this project! Where can I learn more about building things like this?
A: The world of DIY electronics and microcontrollers is incredibly rewarding. A fantastic place to start is by learning the fundamentals of electronics and programming. Online learning platforms like Edureka offer comprehensive courses on everything from basic programming to advanced IoT development that can take you from a beginner to a confident creator.

Join the CyberDudeBivash Community

Want more DIY tech projects, privacy guides, and security tips? Subscribe to our newsletter for regular updates. Let’s build a safer digital world together. Subscribe on LinkedIn

Related Personal Security Guides from CyberDudeBivash

#CyberDudeBivash #DIY #ESP32 #Privacy #HiddenCamera #TravelSecurity #CyberSecurity #TechProject #Arduino

Cyberdudebivash