Zx Lee

Personal Blog on Electronics and Programming


July 2013

4×4 Matrix Keypad

Tired of using normal push buttons as input to your system? You should consider including a matrix keypad. Matrix keypad is widely use in our daily life. Often, matrix keypad is available in 3×4 or 4×4. For your information, matrix keypad is a good substitution to normal push button. Matrix keypad offers more input to the microcontroller with lesser I/O pins required as compared to buttons. Consider your system needs 16 inputs, you requires only 8 I/O pins with keypad instead of 16 I/O pins. So you can actually use the extra 8 pins for other functions. Continue reading “4×4 Matrix Keypad”


DIY Printed Circuit Board (PCB)

Today we going to discuss on how to make your own printed circuit board (PCB). Making a home-made PCB is easy with toner transfer method. But first, let us understand more what is a PCB. A PCB is used to mechanically support and electrically connect electronic components using conductive pathways.

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RF Module (Part 2)

If you haven’t check on the first part on RF module explanation, you might want to read it before proceed with RF using library. Here we going to discuss how to implement VirtualWire library with low cost RF module. VirtualWire library does not use the Arduino UART pin (digital pin 0 and digital pin 1).

You can download the VirtualWire library here.

Before we look into the code, let us see some of the functions.

Continue reading “RF Module (Part 2)”

RF Module (Part 1)

Ever wonder how to implement wireless control on your project without spending too much of money? It is possible with cheap radio frequency (RF) module, consists of transmitter (Tx) and receiver (Rx). The RF module has to be used in pairs which are of the same frequency. Frequency of low cost RF module available are 315MHz and 433MHz.

Continue reading “RF Module (Part 1)”

RC Servo Motor

RC servo motor is commonly as actuator which requires precise control of angular position. An example of application of servo motor is robotic arm. Inside a servo motor, there is a motor, gearbox, potentiometer and control circuit. The potentiometer is used to measure the position of the shaft and the control circuit will control the shaft accordingly.

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7 Segment Display

7 segment display is widely used in applications such as digital clock, electronic meters and much more. 7 segment can offers display of decimal numbers and some alphabet. So 7 segment display can be used to display both decimal numbers (0-9) and hexadecimal numbers (0-F).

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Ultrasonic Sensor HC-SR04

Ultrasonic sensor is a sensor that works on principle similar to radar or sonar. It generates high frequency sound and calculate the time interval between the sending of signal and the receiving of echo. Therefore, ultrasonic sensor can be used to measure distance. HC-SR04 ultrasonic sensor consists of a transmitter, a receiver and a control module.

Continue reading “Ultrasonic Sensor HC-SR04”

Liquid Crystal Display (LCD) HD 44780

Hitachi HD 44780 LCD controller is one of the most common used character LCD. It is available in variety of size such as 8×2, 16×2 or 20×4. This kind of LCD controller is easy to interface and there are also many libraries made for this controller.

Continue reading “Liquid Crystal Display (LCD) HD 44780”

Voltage Regulator LM7805

Voltage regulator is a device used to provide a constant output voltage. Most of the circuits uses 5V supply. With a voltage regulator, LM7805 you can make your own 5V supply easily.

Lets look at voltage regulator 78xx family. The xx specifies the output voltage of voltage regulator. For example, 7805 means 5V output voltage, 7812 means 12V output voltage. There is also 79xx family which provides negative output voltage. 7905 would provide a -5V output voltage.

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