How to Make a Burglar Alarm Circuit for Your Home Security?

These days home security systems are given great importance everywhere. However these security automation systems are very expensive to implement. Here I will help you to make a simple IR security system by your own using an Infrared-photodiode pair.

Earlier we had already published another intruder alarm circuit diagram which was based on LASER and LDR. However it has a probability that the thief might see the LASER beam and avoid theft alarm easily. This simple circuit will give you an insight into how do burglar alarms work.

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Analog to Digital Converter Using PIC16f877A Microcontroller - Beginners Guide

What is meant by Analog to Digital Converter (ADC)? An ADC converts analog signal to it's corresponding digital signal.

How to convert analog signal to digital signal? CircuitsGallery.com has already posted ADC using LM324 IC, in that ADC tutorial I had already explained Analog to Digital Converter how it works.

While dealing with Microcontrollers we may face many situations where we have to use ADCs (Digital voltmeter, ammeter etc.). In such situations it's difficult to set up a separate ADC hardware circuit for our project.

So How to Use Analog to Digital Converter (ADC module) in PIC microchip microcontroller? PIC microcontrollers have inbuilt ADC module making easy Analog to Digital conversion.

In this article I’m gonna show you how to make use of ADC module in PIC16F877A microcontroller with the help of Mikro C Pro compiler and Proteus 8 simulator.

At the end of this tutorial, I did the video demonstration and simulation about analog to digital conversion using PIC16f877a.

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LCD interface with Microcontroller PIC: Beginner’s guide

How to interface LCD (Liquid Crystal Display) display module to PIC microcontroller? LCD is a passive component, that is it does not make any light but just modifies the light passing through it for alphanumeric displays. LCD is exclusively manufactured to be used with microcontrollers, which means that it cannot be triggered by usual IC circuits. This embedded program shows how to connect PIC to LCD display module with microcontroller programming.

Here 16x2 LCD interfaces with the PIC microcontroller. This type of LCD screen can display 2 lines with 16 characters each. Every character consists of 5x8 or 5x11 dot matrix. It can display all the letters of alphabet, Greek alphabet, mathematical symbols, punctuation marks etc. It is also likely to display symbols prepared by the user. Other positive features consist of automatic message shift (left and right), cursor appearance, LED back light etc. Interfacing LCD to microcontroller is quite simple program for beginners and easy to understand.

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IR Transmitter and Receiver Circuit for Best Remote Control System

A remote control system for appliances makes our life smarter and easier. The wireless remote control circuit may be based on IR waves or RF waves, IR being cheaper. An IR emitter circuit is based on TSOP at the receiver section. Each TSOP operates at a particular frequency which depends on a number present on it. So each TSOP requires specific remote controller for its operation. There comes the importance of IR universal remote control which can be used to operate all normal hobby circuits.

Here the basic principle of operation is Frequency Shift Keying (FSK). It enables to generate variable frequency so that it can detect different TSOPs.We are using two 555 timers here, both operating in astable mode which then drives the IR led.

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12v Led Battery Level Indicator Circuit (Led Bar Graph)

Most often, I come across many situations where I needed a lead acid battery voltage level monitoring circuit. Here is an example; I use lead acid battery for my inverter and so it requires constant voltage charging. But inverter provides current charging only, so I use a self-made battery charger circuit which provides a constant 14 volt charging. Charger output should be maintained at 14 volt; else it will reduce the battery life.

This made me think of building a battery voltage monitor circuit one for myself, and here is my circuit design. It can indicate voltages using Led’s in levels of 8 with variable sensitivity. You can use this led level indicator for monitoring battery voltage.

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Simple Continuity Tester Circuit Using 555 Timer

Normally we use continuity testing to check if a circuit, PCB or cable is continuous or not. It also helps us to check if a bulb is burnt out or not. Simply we can do the test by using a battery and a led or buzzer, but they are not precise or accurate.

Usually we use a continuity test multimeter which is little bit costly and bulky too. Also these give a positive indication even when there is 100 ohms of resistance between the probes.

So how to make a continuity tester which has no such kind of drawbacks. This circuit is built around a common 555 chip wired in astable mode. The continuity test circuit can precisely judge continuity as that low 6 to 8 ohms(which can be set by using the preset). Speaker is used to indicate the continuity.

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Simple Door Phone Intercom Circuit Schematic (Duplex)

A door phone intercom system provides a two-way conversation that is cost free. It can be very useful in hospitals, hotels and as a free of cost communication to a friend’s house.

Earlier I had already published another two way communication intercom circuit but it had the disadvantage of switching (same speaker is used both as mic and speaker based on the switch positions).

The main component used here in this two way intercom circuit is an 1895 IC. It is a 1 watt audio amplifier. Here we are using two condenser mics and two speakers for communication. Calling tone is generated by using melody generator IC UM66.

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