Introduction: NowGuard Security System

This instructable was created in fulfillment of the project requirement of the Makecourse at the University of South Florida (

This in the NowGuard security system, a rapid deployment security system great for simple security needs.

Step 1: Lets Begin...

* All of the parts in this project were fabricated in Autodesk Inventor and printed using a 3D printer. Maker should have some knowledge of 3D printing to modify and edit parts as necessary. In addition some parts of the build may require some soldering, experience there will be useful as well.

Materials Required:

  • 1 Arduino board along with USB cable
  • 1 HC-SR04 Ultrasonic Sensor
  • 1 RGB LED light
  • 1 Adafruit audio fx mini sound board - wav/ogg trigger - 2mb flash
  • 1 Adafruit mini spy camera with trigger for photo or video
  • 1 4Ohm 3W Full Range Audio Speaker
  • 1 2 Watt Audio Amplifier
  • 1 3.3x2.2 in. bread boardD
  • 1 Push Button
  • 3 SG90 Micro Servo Motor Mini
  • Many jumper cables - male to male, male to female, female to female
  • Hot glue gun
  • Wire Stripper
  • Soldering tools

Step 2: Control Diagram

The now NowGuard Operates as a security that uses an ultrasonic sensors to detect the presence of a person or object within specified ranges set by the user. For my project they are three ranges far, medium, and close, depending on which range the person or object is detected in the Nowguard sends a warning message or sets of an alarm in conjunction it also takes a picture or video every time it detects something and saves it on an SD card for later review.


The servo connected to the sensor at the top, when powered on scans an area between 0 and 180 degrees. Based on the the three ranges set in the code, when the NowGuard detects something or object within one of the ranges, the sensor stops in the angle position in which it detected the object, and then the servo connected to the camera moves to the same angle position. (As this point sensor and camera are facing the same direction). The camera takes a picture and the system plays a warning message Ex. "Please Step Back", continuously until the object has moved out of the scanning range. Once the object has moved the sensor returns to scanning the area.

Step 3: Time to Print.

CAD files used for printed parts attached, download and modify/redesign to your needs.

Step 4: Wiring

Like in the image above i would recomend placing all parts and wires on a work table table to make and keep tack of connections. There are 3 servo motors label them with a piece of tape and sesginate them.

Ex. I numbered/named them based on the part they moved .. Servo #1 camera, Servo #2 Sensor, Servo #3 Shaft.

Arduino Pin Connections: From Arduino to --> Item specified

RX0. -

TX1. -

2. Sensor Servo input

3. Shaft Servo input

4. Camera Servo input

5. Pin 1 of sound board "Range0"

6. Pin 2 of sound board "Range1"

7. Pin 3 of sound board ''Range2 "

8. Camera Trigger

9. Trigger Pin HC-SR04

10. Echo Pin HC-SR04

11. Red Pin of RGB LED

12. Greed Pin of RGB LED

13. Blue Pin of RGB LED

A0. Wire Connected to A1

A1. Wire connected to A0

A2. Push Button // Push button is wired with pull up resistor to prevent bouncing

A3. Push Button

A4. - Pin 0 of soundboard

A5. -

Ensure a parts are powered by being connect to +5 V and ground.

**In regards to the image with the speaker, omitting the connections to the Arduino, that is how the sound board should be wired to amplifier. Reference Adafruit PDF.

Step 5: Arduino Sketch

Download the Arduino sketch to your Ardunio board.

Step 6: Assembly 1.

Now that the connections have been made sketch up loaded, and operation has been achieved and understood. Its now time to repeat the process but now including actual parts.

  1. Lets Star with the ultrasonic sensor and its enclosure, you will notice that it does no fit with the pins still attached. (Soldering starts now) Remove/cut the pins. Obtain 4 pieces of wire about 12 inches long each(can cut access later) With wire stripper expose copper and then feed each wire into one of the 4 small holes in the "sensor cover" part. After proceed to solder the wires to the HC-SR04. The HC-SR04 should now fit snug and you can place the back cover on.
  2. Connect the shaft and the Sensor holder. Insert the sensor servo, feeding the wire through the shaft.
  3. Feed the wires connected to the HC-SR04 though the sensor cap, around the "sensor servo" and then through the shaft.
  4. Close the cap, and firmly press sensor enclosure sensor against shaft of the servo motor to ensure good connection. ( you can you hot glue to help ensure tight connection.)

At this point the moving shaft and the rotating sensor is complete, set aside.

Step 7: Camera and Sound Board

Camera Operation:

"... Connect the red wire to 3.7V-5VDC and the black wire to ground. Then use the white wire to control the camera. When touched to ground for under half a second, the camera will take a photo and stick it in a PHOTO folder on the SD card, numbered from PIC000.jpg up to PIC999.jpg. The red LED will blink briefly. When the trigger wire is touched for over a half second, it will start taking a video clip with audio from the mini microphone. The LED will stay on during the entire recording. Touch it again for half a second+ to stop."


480p video and 1280x720 photo module, with a driver board that is about 1 square inch in size, with a microSD card holder.

Sound Board Operation:

For set up and operation of the sound board and how to get your custom audio files on it download the Adafruit sound board PDF that I've attached, attached are also the audio files I used for reference.


For application in the NowGuard the power, ground, and trigger wires attached to the camera are to short and need to extend so that they can extend through the camera holder and into the main box, you will need to either solder or strip and tie a new set of wires about 8'' for connection and free movement. (green, orange, and red wires seen coming from the top)

Step 8: Assembly 2

Proceeding to the main body(Be sure to reference images) ..

  1. Secure Bread board and Arduino to bottom of box with hot glue.
  2. Feed USB cable through cable 'cable hole' and connect to Arduino board.
  3. Attach push button and secure with hot glue.
  4. Secure the "shaft servo" to the bottom of the box top aligned with the hole for the servo shaft, do the same for the RGB LED inserting from the top an gluing at the bottom.
  5. Glue the Speaker to the box top, aligned with the speaker grill.
  6. Glue the sensor servo to the bottom o the box aligned with the hole for the camera stand.
  7. Reestablish all connections discussed in the wiring diagram step.
  8. Guide camera through "camera stand" and connector to bread boards
  9. Secure placement of camera in camera colder and place cover.
  10. Secure cover to main box with screws.

Step 9: Finish

Now that the main assembly is complete, its time to make make your now guard system look legit. I decided to cover mine with a simple and carbon fiber vinyl wrap and used some red crafting tape for the trimming. Gold metallic paint was used to paint the badge and white to trace the letters.

Have fun with your newly constructed NowGuard Security System!