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Category Archives: Tips and Tricks

H-Bridge to drive white LED arrays directly from the AC mains supply

Posted on August 23, 2013 by R-B Leave a comment

The classical H-bridge circuit is widely popular in driving DC motors in robotics applications. This article talks about a novel application of the H-bridge circuit for driving white-LED arrays directly from the AC mains in full-wave current-limited mode to realize an excellent flicker-free, energy-efficient solid-state lamp. The circuit controls and maintains the LED excitation current in both negative and positive half cycles of the excitation voltage to a constant level by way of electronic switches operating alternately during the positive and negative excursion of the excitation voltage.

Low-cost thermostat design for cooking appliances using PIC10F204

Posted on August 20, 2013 by R-B Leave a comment

Countertop cooking appliances, such as electric ranges and skillets, use an adjustable thermostat to vary the heat output. In traditional appliances, a mechanical thermostat was used in series with the heating element to control the current through the element. While this technique is inexpensive, it is less accurate and less reliable over time because the mechanical components wear out. This application note from Microchip describes a low-cost microcontroller-based design which eliminates these drawbacks. The solution uses the PIC10F204 microcontroller, which gathers user inputs from a potentiometer and control current to the heating element via a triac. The application note also

Data recovery from a dead SD card using Arduino

Posted on August 19, 2013 by R-B Leave a comment

A Secure Digital (SD) memory card is the most standard memory card for use in mobile electronic devices, such as cell phones, digital cameras, GPS devices, and tablet computers. Communication with an SD card can be done in one of two modes: the SDIO mode and the SPI mode. By default, the SD card operates in the SD mode, which is much faster than the SPI mode and is thus more preferable in the portable devices for achieving high-speed data transfer. If you have a damaged SD card that contains valuable information, this example shows you might have a chance

Implementing digital filters using PIC18F microcontrollers

Posted on August 12, 2013 by R-B Leave a comment

Microchip’s PIC18 family of microcontrollers are popularly known for their logic and controlling functions. In addition, these microcontrollers have builtin hardware multipliers and multiple file pointers. These features, along with the built-in analog-to-digital converter (ADC), make PIC18 microcontrollers a competent choice for applications where logic and controlling functions are combined with signal processing applications. This application note demonstrates how the PIC18 family of microcontrollers can be used to implement digital FIR and IIR filters.

Interfacing AC power lines with PIC microcontrollers

Posted on August 9, 2013 by R-B Leave a comment

Applications like automatic power factor correction, power measurement, and power line monitor require interfacing the high voltage AC power lines to microcontrollers. This application note from Microchip describes a simple method for measuring parameters from the AC power line by using only one external resistor, and is more reliable than using a bulky and expensive transformer. This method takes advantage of the input static protection circuitry that exists on I/O pins of a CMOS PIC16C5X. These protection circuits are designed to short the inputs to the power supplies when a large overvoltage is applied, thus protecting the chip from static

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