Friday, December 16, 2011

Mobile Phone Battery Charger

This battery charger circuit is for Sony Ericsson standard batteries, Li-Polymer type, with a nominal voltage of 3.6V and a capacity of 900mAh. But you can also charge Nokia batteries as well.

Charging lithium cells is fairly straightforward. You generate a well regulated voltage and ensure the charging current is sufficiently low so as not to cause overheating problems. Also, when the correct terminal voltage as been attained, it is important to shut down the charging process at that point.

Friday, December 9, 2011

Low Cost Capacitive Touch Switch II

In my previous post of capacitive touch switch, it gives the o/p as long as you touch it. Means it was only drive the load when you touch it, and when you remove your hand/finger then it was not able to drive the load. Tough that touch switch circuit can be used in various apps but does not meet my requirements. So by changing the circuit a little bit i am able to design a touch switch that behave like a normal switch i.e touch to on and touch to off.

Wednesday, December 7, 2011

Low cost Capacitive Touch Switch

Common designs for touch switch switches detect a decrease in resistance either when a user's fingertip connects a contact to the circuit's common ground. The circuit shown operates by sensing an increase in capacitance that results from touching a contact. Although a straightforward design might require a complex circuit, the design shown offers a low-cost approach that uses few components.

Friday, December 2, 2011

PICkit 2 Clone

There are many PIC programmer available, commercial and DIY devices. As Microchip introduces the new microprocessors the programming software got to be updated accordingly playing catch-up with the PIC manufacturer. That is the root of the problem with third-party PIC programmers. Microchip's PICkit 2 is the low cost ICSP programmer for Flash PICs with USB interface introduced by Microchip. Only subset of PIC microcontrollers is supported, but the list is including all the recent devices from PIC16, PIC18 and PIC24 families and certainly covers all the PICs you are most likely want to use. It is fully integrated with Microchip’s MPLAB IDE and allow not only program but debug applications as well.

Friday, November 25, 2011

Telephone Line Powered LED Lamp

This small and bright LED lamp is telephone line powered, means it uses the power of our telephone line. There are about -40v to -50v at telephone line, LM317T is used to adjust them according to our demand.

Wednesday, November 16, 2011

PIC Based Auto Dimmer

The operation of the dimmer is based on phase control; during a full cycle of an AC waveform, a thyristor will only allow a part of the waveform to be delivered to the load. Take a look at the following waveforms:


The only difference is that the waveform on the left will bright the lamp higher than the waveform on the right. That is because, on the left waveform, the triac will be conductive earlier than the triac shown in the right waveform.

Saturday, November 12, 2011

Serial Communication With PIC18F452

In this tutorial I will explain how to practically do a simple communication over RS232 interface. In this tutorial i ll send and receive the data using serial port, in two devices. Also you can control your home appliances using PC serial port with the help of PIC. RS232 is serial interface that means that data is transferred BIT by BIT at a time. Since data is transferred BIT by BIT so we need only a single wire two send data and an another one to receive data. One more common wire (called GND) is required between two separate circuit to enable current flow. So a total of three wire are required for communication.

Monday, November 7, 2011

LED Flasher

This LED flasher is based on 555 timer. One can use this flasher circuit either on bike/cycle or in police car!. The operating voltage of the circuit is 9v, but you can also use it at 6v. 

Two sets of six LEDs are used here, but you can extend it to 40 each set. Flash cycle is determine by the RC time constant. However by using the pot you can set the flash rate of your choice.

Saturday, November 5, 2011

LM3914 Based Battery Voltage Monitor

This voltage monitor is made to display the voltage of 12v battery (for UPS) on LEDs. For this purpose LM3914 is used. The voltage range decided to display is 10v to 13.5v for 12v battery. LM3914 is display driver that can be used in dot  mode or in bar mode; dot mode, with only one led is lit at a time, and in bar mode where it lights leds progressively when the voltage increases.

Thursday, November 3, 2011

UPS Battery Charger

The battery charger used in the ups are very slow in nature, means the charging current is low (about 1 - 2 A). So they required a lot of time to charge a high AH batteries. This charger is build around LM338 that can charge the battery with 5a current and fast in nature.

This circuit has Auto cut off facility also. This High current charger can be used for the Fast charging of sealed lead acid batteries. This charger can give 5 Ampere current for quick rejuvenation of the battery. It uses an Adjustable voltage regulator so that 6 volt and 12 volt batteries can be charged. When the battery acquires full charge, charging process will be terminated.

Thursday, September 22, 2011

Contact less IR tachometer using PIC16F628A

Tachometer is a device that gives the information about the rotational speed of any shaft or disc. It usually measures the speed in revolutions per minute (RPM). 
I want it to measure the speed of motor so for this i searched the net and found various design but unfortunately they don't worked for me, don't know why?. So i decided to make my own tachometer using PIC16F628A micro-controller and LCD.

Wednesday, July 6, 2011

Persistence of Vision (POV) Coding using PIC16

In this section i will tell you about the POV coding using PIC16F877A in C language. Persistence of vision is the phenomenon of the eye by which an afterimage is thought to persist for approximately one twenty-fifth of a second on the retina.
My plan is to use the fan from PC power supply; for rotating purpose. Now first of all i want to tell the two things. 1st i don't have smaller MCU that is why me using 40 pin, you can also use 28 pin if you have any. 2nd due to my hardware design fault, actually soldering fault,  i missed the RB0 pin; so to compensate it i used RD0. You can change the coding if you want for your ease.

Tuesday, June 28, 2011

SIRC Decoding and Appliances Control

In this tutorial i will show you how to decode the Sony SIRC protocol and control the home appliances like bulb, fan etc with the Sony remote control. Infrared remote control has been around for a very long time now. Each manufacturer use different set of protocols. For example, RC80 is used by Panasonic, RC5 is used by Philips, and SIRC is used by SONY, which is one of the simplest to decode.

Modulation is used to prevent the other light sources interference. This modulation is center around different frequencies depending on manufacturer and varies from 32KHz to 56KHz. In the case of SONY, the modulation center is 38-40KHz which means we need a IR-receiver that can receive the modulation infrared light and convert it to a TTL signal for a PIC. There are a number of IR-receivers available, each having a specific center frequency that they are more sensitive too.You can use whatever you want just remember the pin outs; i am gonna use to local IR receiver.