• Skip to main content
  • Skip to primary sidebar

Making Easy Circuits

Learn and build electronic circuits

You are here: Home / Sensors and Detectors / Transmitter Bug Detector Circuit

Transmitter Bug Detector Circuit

Last Updated on November 17, 2024 by Admin Leave a Comment

The Bug detector is a highly sensitive transmitter detector designed to detect transmitters with an output power as low as 10mW, even from a distance of approximately 15 feet. This ingenious device offers a simple and efficient solution for locating bugs and dealing with them effectively.

How it Works

Equipped with a sensitivity control, skilled operators can precisely pinpoint hidden transmitters. Additionally, a minor modification allows for the replacement of the LED indicator with a small meter, giving the project a more technical appearance without necessarily improving its performance.

With minimal power requirements, only about 4mA on standby and 10mA when activated, the Bug detector can be powered by a 9V pp3 battery for an extended period.

The entire project, excluding the optional meter, is expertly mounted on a 35 x 60mm PCB, ensuring easy integration into a compact enclosure during construction.

Circuit Diagram

The circuit diagram of the Bug detector is illustrated in Figure 1, while Figure 2 displays the component overlay of the PCB.

transmitter bug detector circuit
transmitter bug detector circuit PCB design

Constructing the device involves creating a coil L1 by meticulously winding six turns of 24 gauge enameled copper wire to a 5mm diameter, with the use of a drill bit as a former.

Proper soldering techniques are employed to ensure a solid joint.

It is essential to observe the correct polarity of diodes and IC during assembly, but otherwise, the construction process is straightforward. Although the preset resistor RV2 may be omitted and replaced with a wire link, its purpose will be described in the subsequent section.

The aerial, which can be either a few inches of ordinary flexible wire or a telescopic antenna, plays a crucial role in the Bug detector's functionality. For optimal results, a longer antenna is generally preferred.

How to Test

In the testing and usage phase, once all components and wiring are verified, connecting a battery to the project will initiate the Bug detector.

Adjusting the variable feedback resistors to their maximum resistance ensures maximum sensitivity, although it may cause the LED to flicker unexpectedly.

Fine-tuning the coarse control RV2 will eliminate random triggering.

Readers who desire greater sensitivity at lower frequencies (e.g., 27 to 50 MHz) can enhance the Bug detector by soldering a 5.5 to 65p variable capacitor across the coil or increasing the number of coil turns to alter the bandwidth.

Conversely, removing C1 and a few turns from the coil will enable coverage of the VHF/UHF spectrum.

Notably, while the prototype features a preset RV1, a panel-mounted potentiometer with a pointer-style knob is recommended for ease of use.

To employ the Bug detector effectively, a slow sweeping action should be adopted while traversing the room.

If no signal is detected, repeat the process while adjusting the aerial's position. It is worth considering that most bugs have a vertical aerial, so using oppositely polarized aerials (one flat and one upright) can significantly affect detection sensitivity.

Aligning the aerials in the same plane enhances signal detection.

Patience and practice are essential, as locating a transmitter may require adjusting the sensitivity carefully, especially when the bug is situated several meters away.

In conclusion, the Bug detector offers a reliable and user-friendly solution for detecting and dealing with transmitters covertly placed in the vicinity, making it a valuable tool for bug detection and security maintenance.

You'll also like:

  • 1.  How to Build a Soil Moisture Sensor Meter with Automatic Water Sprayer Circuit
  • 2.  How to Make a Simple Shadow Detector Circuit
  • 3.  Inductive Non Contact Current Sensor Circuit
  • 4.  Simple Smoke Detector Circuit
  • 5.  Simple Infrared Thermopile Sensor Circuit Explained
  • 6.  Automatic Day Night Triggered Car Headlamp Circuit

About Admin

Hey friends, Thanks a bunch for stopping by this site! I am an engineer with a Bachelor of Engineering in Electronics and Telecommunication. One of my passions is gathering information from all sorts of electronics books and tutorials. I then take that information and compile it into a language that is super easy to understand. My goal is to make those complex electronics circuit concepts and technical terms much more accessible for all the new and budding electronics engineers out there. I can also design customized circuit diagrams as required by the users.
If you have any questions related to this field, please do not hesitate to drop a comment! I am always here and ready to help you out with any queries you might have. I cannot wait to hear from you!

Reader Interactions

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Primary Sidebar

Categories

  • 3 Phase (4)
  • 8051 Microcontroller (1)
  • Arduino (11)
  • Audio and Amplifier (102)
  • Automation (8)
  • Battery Chargers (64)
  • Bicycle Projects (4)
  • Car and Motorcycle Projects (39)
  • Datasheets (10)
  • DIY Projects (5)
  • Electrical (15)
  • Free Energy (6)
  • Games Projects (2)
  • High Voltage (14)
  • Hobby Projects (30)
  • Household Circuits (2)
  • IC 555 Circuits (5)
  • Ignition Circuits (2)
  • Indicators (50)
  • Infrared (6)
  • Inverter Circuits (29)
  • Lights and Lamps (97)
  • Medical (8)
  • Meter and Tester Circuits (38)
  • Motor Driver (17)
  • New Circuits (56)
  • Oscillators (30)
  • Pets and Pests (5)
  • Power supply (80)
  • Protection Circuits (25)
  • PWM (9)
  • Remote Control (20)
  • Security and Alarm Circuit (48)
  • Sensors and Detectors (66)
  • Signal Processor (23)
  • Solar Controller Circuits (62)
  • SSR (3)
  • Temperature Controller (20)
  • Timer (25)
  • Transformerless (7)
  • Transmitters (12)
  • Tutorials (45)
  • UPS (2)
  • Voltage Regulators (57)
  • Water Sensor and Controller (29)
  • Home
  • Privacy Policy
  • Contact
  • Disclaimer
  • Copyright

© 2025 · Making Easy Circuits