Arduino radar using sound waves

A radar system uses high frequency radio waves for object detection. A high-power RF pulse is transmitted into space and its echo reflected off from an obstacle is recorded. By computing the time elapsed between the transmitted and reflected pulses, and knowing that the electromagnetic wave propagates at a constant speed of light, the radar computes the distance of the obstacle. Because the speed of radio waves is so high, the time lapse is usually very small, and therefore requires sophisticated electronics for range detection. The time lapse would be easier to detect if the waves with lower propagation speeds were used, for instance, sound waves that travel at a much slower speed (~ 340m/sec in air) than light.

Dejan Nedelkovski from How To Mechatronics illustrates the principle of radar using ultrasonic sound waves. In his project, he used an HC-SR04 ultrasonic ranging sensor module for measuring distance to an object, similar to the echolocation technique used by mammals like dolphins and bats. The HC-SR04 is a fully-integrated module with onboard transmitter, receiver, and control circuit. It can measure an object distance ranging from 2cm – 400cm with an accuracy of 3mm. The HC-SR04 sensor is mounted on a servo motor for scanning the surrounding. An Arduino board is used to control the angular position of the servo during scans. The echo data output from the ranging sensor is received by Arduino and is sent to a computer along with the angular positions along the scan through a USB port for post processing.

Arduino radar using sound waves
Arduino radar using sound waves

On the computer side, a PC application was developed using the Processing platform to retrieve the radar echo data, combine it with the angular position data, and visualize the radar signature on the screen. Check out the following video to see this radar in action.

Using VL53L0X With Arduino to Measure Height

Usually, when measuring a child’s height at home, a mark is drawn on the wall then the height is measured using a measuring tape. This process is not always easy and it may has low resolution. In an attempt to simplify this procedure, a new project was developed using an Arduino and a distance sensor.


The main parts which were used in this project are:

  1. Arduino Nano, the microcontroller which will read sensor’s values and display the results on the screen.
  2. MPU-6050, 3 axis gyroscope with 3 axis accelerometer
  3. VL53L0X, Distance Sensor
  4. RGB backlight LCD 16×2
  5. Wooden box and acrylic plate.

VL53L0X is a laser-ranging sensor that uses Time Of Flight (ToF) measurements of infrared pulses for calculating the distance of the facing surface. It can measure distances up to 2 meters with a resolution of 1 mm. This sensor works over an input voltage range of 2.6V to 5.5 V, and the measured values can be read through an I²C interface.

VL53L0X Sensor - Image courtesy of Pololu
VL53L0X Sensor – Image courtesy of Pololu

To get the best result, Vl53L0X must be attached on the bottom of the box as shown in this figure.


MPU-6050 is a low power, low cost, and high-performance motion tracking device, it contains 3-axis gyroscope and a 3-axis accelerometer with an onboard Digital Motion Processor (DMP™) which can be programmed with firmware and is able to do complex calculations with the sensor values and uses I²C interface. This sensor is used here for detecting the horizontal direction and for measuring X and Y axis acceleration.


This project has two working modes, Normal Mode and Measurement Mode.

In the Normal mode, the height is always displayed on the LCD, and the color of the LED indicates whether the measurement is horizontal or not. While in the Measurement mode, a button should be held while putting the device on the head, the LED will light blue and the value of the height will caught when the horizontal state is detected.



The code and more information about this project are available here.

Essential 10 Arduino DIY Arduino board schematics


James @ has compiled a list of the most popular Arduino boards including schematics and PCB. You can download the files here.

Arduino is now a very popular open source development boards, many people are using the Arduino Development Board to develop interesting, creative product prototypes. Do it yourself DIY Arduino Development Board, isn’t it more fun? Want to DIY Arduino Development Board, must have been around schematics and PCB, specially collected 10 Arduino Development Board and expansion board circuit diagram and PCB project files, easy do it yourself DIY, information collected is not easy, let me see and cherish!

Essential 10 Arduino DIY Arduino board schematics – [Link]

Reverse engineering a server CPU voltage regulator module


Andy Brown wrote a detailed article on reverse engineering a CPU voltage regulator:

A recent ebay fishing expedition yielded an interesting little part for the very reasonable sum of about five pounds. It’s a voltage regulator module from a Dell PowerEdge 6650 Xeon server.
I originally bought this because I had the idea of salvaging parts from it to use in another project. These are high quality modules that will have very good inductors and sometimes an array of high value ceramic capacitors that could be re-used (ceramics of at least 22µF at 16V and above are rather pricey at the moment). So the VRM arrived and I was rather impressed with the build quality and decided to have a go at reverse engineering it.

Reverse engineering a server CPU voltage regulator module – [Link]

Sonicare toothbrush teardown: microcontroller, H bridge, and inductive charging


Ken Shirriff did a teardown of a Sonicare electric toothbrush:

The photos below show the top and bottom of the toothbrush internals. I expected to find a simple, low-cost mechanism, so I was surprised at how much complexity there was inside. The vibration mechanism (right) is built from multiple metal and plastic parts screwed together, requiring more expensive assembly than I expected. The circuit board is literally gold-plated and has a lot of components, even if it doesn’t quite reach Apple’s level of complexity. Overall, the toothbrush’s internal design is high quality (except, of course, for the fact that it quit working, as did an earlier one).

Sonicare toothbrush teardown: microcontroller, H bridge, and inductive charging – [Link]

LT3086 – 40V, 2.1A Low Dropout Adjustable Linear Regulator with Monitoring and Cable Drop Compensation


Graham Prophet  @ discuss about LT3086 LDO.

The 40V, 2.1A low dropout linear regulator (LDO) includes current monitoring with externally settable current limit and temperature monitoring with external control of thermal limit temperature. The device includes a programmable power-good status flag, cable drop compensation and easy paralleling. The current reference in the LT308x LDO family provides regulation, independent of output voltage.

The new 800V CoolMOS MOSFET from Infineon


Thomas Scherer @ shares the news about a CoolMOS Mosfet from Infineon.

The latest 800V CoolMOS P7 800V MOSFET from Infineon is based on their superjunction technology. The device is available in twelve classes of RDS(on) beginning with  0.28 Ω and in six package options. It is particularly suited to high voltage switching applications, flyback applications including adapter and charger, LED lighting, audio SMPS, AUX and industrial power.

The new 800V CoolMOS MOSFET from Infineon – [Link]

230V AC dimmer, mains isolated, using PIC12F629


This is a very simple mains isolated dimmer with a triac output (phase control). It uses timer0 to do the timing.

There is no user interface, the value of the triac ignition delay after a zero crossing is defined by setting the reload value of timer0 (Tmr0) in the software directly. This value can e.g. be derived from a user interface or sensor or some algorithm. In the example it is stepped trough a number of values sequentially.

230V AC dimmer, mains isolated, using PIC12F629 – [Link]


Short circuit tracer uses low power


shares his design idea on

This Design Idea presents a low power short circuit finder that capitalizes on the ear’s sensitivity to changes in frequency. The heart of the circuit is a voltage-to-frequency converter (based on Linear Tech’s AN45, Figure 13, by Jim Williams), which converts millivolt-level DC voltages to a wide range audio frequency output.

Short circuit tracer uses low power – [Link]

L293D Motor Direction Controller


baelza.bubba @ show us how to build a DC motor direction controller using L293D.

I designed this DC Motor Direction Controller so that I could give direction control to DC motors that I am building into mini tools (drill, lathe, table saw, solder smoke extractor, etc.). While, I don’t need direction control for all of the tools that I’m building, it IS necessary for some. Plus, who doesn’t want to spin their DC motor backwards?

L293D Motor Direction Controller – [Link]