Raspberry Pi I/O capabilities can be expanded by adding one or cascading a number of shift registers. In this design 74HC595 example is shown. 74HC595 is a very popular and relatively cheap IC. There are assembled modules based on this ...

This post is about building a 3-digit countdown timer based on Arduino MEGA. Up/Down counter also available at this link. The timer will wait for 3-digit number to be entered via 4x3 keypad and then start counting down to zero ...

LED Battery Level Indicator can be built using Arduino UNO board and 10 LEDs. Similar design that uses 2x16 LCD display can be found at this link. RGB LED variant is here. For Raspberry Pi version click here. I/O lines ...

When working with multiple 7-Segment displays a multiplexing scheme is required in order to simplify the design and save Raspberry Pi I/O pins. Such implementations shown in this design. As can be seen from a schematic diagram 2 7-Segment displays ...

MAX7219 is a serial input/output common-cathode display driver. It can interface the microcontroller to 7-segment numeric LED displays, bar-graph displays, dot matrix display or  individual LEDs. This IC has some very useful features like built in decoder, multiplex scan circuitry, ...

This post is about building a simple 0-5V 3 digit voltmeter using Arduino UNO compatible board and 4x20 LCD display. This design should also work on all similar boards, I’ve tested it on Arduino Mega and UNO boards.  No additional ...

Arduino Ohm Meter is one of the simplest circuits that can be built with minimal number of required components. As can be seen from design schematic a standard 2x16 LCD display and 3 resistors are all you need to complete ...

Solar power mobile charger can be built by tweaking digital power supply schematic. The Software/Hardware stayed almost the same as the original circuit.Current design has the same overcurrent protection and output voltage can be changed by pressing SW1. Voltage and Current ...

Here is another Arduino based design and this time I’ll show you how a 4-Digit Code Electronic Lock can be built with Arduino Mega or compatible boards. For similar design based on PIC16F877 click this link. The I/O I’ve used ...

3 Digit Dot Matrix Display with SPI interface is an advanced version of recently published 7x5 Dot Matrix Character Generator project. This design is more complex as it contains 4 microcontrollers. Three PIC16F88 were used to control 7x5 Dot Matrix Displays, ...