Burglar Alarm

Nov.23, 2010 in New Circuits

The circuit illustrated here is used as an Burglar alarm. LDR is kept at such a place that when thief enters our house then a shadow will fall on the LDR. A small beam of light source is also needed to supply continuous signal to LDR. For best Light source we can use Laser diode which will work for few KMs. For home use Infra Red LED’s will be good and will be tricky to thief and works with same efficiency at night.
This circuit uses a popular timer I.C which is 555. I.C 555 is connected as comparator with pin 6 connected with positive supply, the output goes high-1 when the trigger pin 2 is at lower than 1/3 level of the supply voltage. Conversely the output goes low-0 when it is above 1/3. So small change in voltage of pin 2 is enough to change the output state of pin 3 from 1 to 0 and 0 to 1. The output has only two states high and low and can not remain in any intermediate stage. It is power by 9V battery for portable use. The circuit is economic in power consumption. Pin 4,6& 8 is connected to the positive supply and pin 1 is grounded.
To detect the present robber we have used LDR and a source of light.
LDR is a special type of resistance whose value depends on the brightness of the light which is falling on it. It has a resistance of about 1 megaohms when in total darkness,but a resistance of only about 2-5 k ohms when brightly illuminated. It responds to a large part of the light spectrum.
The source of light and LDR is so adjusted with a reflector that light will directly fall on the LDR but when robber enters inside then it will block the beam of light and LDR will be under darkness.
We have made a potential divider circuit with LDR and 100 K variable resistance connected in series. Voltage is directly proportional to conductance so more voltage we will get by this divider when LDR is getting light and low voltage in darkness. Sensitiveness can be adjusted by variable resistance. Divided voltage is given to pin 2nd of 555. As soon as LDR gets dark the voltage of the pin 2 drops 1/3 of the supply voltage and pin 3 gets high and Buzzer Beeps.
For Demo we have used simple LED for LED1 may be Red or White Color

Burglar Alarm Circuit Diagram
LED = Light Emitting Diode
LDR = Light Dependent Resistance
IC = Integrated Circuit

Components:-
1) 9V battery with snap
2)LDR
3)Variable resistance 100K ohms
4)Resistance 470 ohms
5)LED
6)IC 555
7)Switch

Electronic Eye

Nov.23, 2010 in New Circuits

ELECTRONIC EYE PROJECT
THEORY AND CIRCUIT DIAGRAM
Electronic eye has much use in this electronic age. Also Known as magic eye. It can be used as an automatic guest indicator at the door, If fitted on the bottom of the door entrance. Once it is installed at the door there is no need to install a call bell. It can also be used at homes or in banks as a burglar alarm.
Fix the LDR to the wooden door or a locker to be protected in such a manner that when anybody tries to open it, a shadow falls on the LDR and the circuit gets activated and produce a pleasant sound through the buzzer.
This electronic eye circuit uses NOT gate from CMOS I.C CD 4049. CD 4049 contains 6 independent NOT gate in one package; we have used here (a) one only. NOT gate output goes high(1) when the input pin 3 is at lower then 1/3rd level of the supply voltage. Conversely the output goes low (0) when it is above 1/3rd level. So small change in the voltage of pin-2 is enough to change the level of output (pin-3) from 1 to 0 and 0 to 1. The output has only two states high and low and can not remain in any intermediate stage. It is powered by a 9V battery for portable use. The circuit is economic in power consumption. Pin 1 is connected to the positive supply and pin 8 is grounded.
To detect the present of an object we have used LDR and a source of light. LDR is a special type of resistance whose value depends on the brightness of the light which is falling on it. It has resistance of about 1 mega ohm when in total darkness, but a resistance of only about 5k ohms when brightness illuminated. It responds to a large part of light spectrum.
We have made a potential divider circuit with LDR and 220 KΩ resistance connected in series. We know that voltage is directly proportional to conductance so more voltage we will get from this divider when LDR is getting light and low voltage in darkness. This divided voltage is given to input of NOT gate.
As soon as LDR gets dark the voltage of input not gate drops 1/3rd of the supply voltage and pin 2 gets high and LED or buzzer which is connected to the output gets activated.
Advantage of using Logic gate is that data can be easily send to other digital interface device ie one can easily fed data to computer using parallel port or for further processing .

Circuit Diagram of Electronic Eye
Part List :
IC 4049, LDR, Resistance 220 K, Buzzer, LED, 9V Battery with Snap and a Switch.

Touch Switch

Oct.25, 2010 in New Circuits

Same Circuit can be use as Touch Alarm, Rain Alarm etc

THEAFS ARE ATTRACTED TO EXPENSIVE THINGS WHEN THEY COME IN OUR HOUSES. WE CAN PROTECT OUR PRODUCT OR THING BY MAKING THEM TOUCH PROOF OR WE CAN STOP ANY UNIDENTIFIED PERSONS ENTRY IN OUR HOUSE BY MAKING DOOR AND WINDOW TOUCH PROOF.THIS CIRCUIT ALERT US WHEN ANY THEAF COME TO STOLE PRODUCTS FROM OUR HOUSE OR TOUCH ANY METALLIC THING AT DOOR / WINDOW OR IN SIDE . WE CAN USE THIS CERCUIT TO PROTECT OUR CAR OR BIKE BY MAKING THEM TOUCH PROOF.
AS WE HAVE DISCRIBE ABOVE THIS PRODUCT GIVE ALARM WHEN ANY HUMAN BODY TOUCH ANY OF THE METTALIC THING WHICH ARE PROTECTED BY THIS CIRCUIT. THIS PROJECT IS WORKING ON TWO TRANSISTORS
WHICH MAKE COMPLIMENTORY PAIR DIRECT COUPLED AMPLIFIER. THIS CIRCUIT BASICALLY A AUDIO OSILATOR FOR OSILATION WE USE COLLECTOR OF TRANSISTOR BC558 WHICH IS CONNECTED TO THE BASE OF TRANSISTOR BC 548 VIA RESISTANCE 18 K .01 or .02 MFD CAPACITOR . TRANSISTOR BC-548 IS WORKING AS A PREAMPLIFIER.
WHEN ANY HUMAN BODY TOUCH THE TOUCH SENSOR WHICH IS CONNECTED TO BASE OF TRANSISTOR BC-548. THIS TRANSISTOR CONDUCT WITH HUMAN SKIN CONDUCTANCE . WHEN TRANSISTOR BC-548 START CONDUCTING IT’S FORCED TO TRANSISTOR BC558 TO START CONDUCTING . SO WE GET ALARM SOUND FROM SPEAKER. WHEN WE TAKE BACK OUR HAND THEN DOES NOT CONNECTED TO BASE OF TRANSISTOR BC-548 . SO IT’S DOES NOT CONDUCT WE DO NOT GET THE ALARM SOUND.

Circuit Diagram of Touch Switch / Touch Alarm / Rain Alarm

The PVC single guitar stand

ORIGINAL SITE

This is my first Instructable and as customary I am just mentioning it. This is another guitar stand made of pvc. I have to admit I built it some time ago but I thought I would share with the community here. It's very simple, so instead of buying more pvc I took mine apart and documented the reconstruction.

Step 1The design

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There are other guitar stands on this site, but I wanted to design mine into a condensed, short and light stand that was sturdy at the same time. Triangles have the properties I was looking for so the design is based on such shape.

Build your own PVC guitar rack stand.

Cheap, Easy, and DIY

© 2011 by Departure Electronics. All rights reserved

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posted on June 20, 2011
by howtomakeaguitarrack
filed under acoustic, build, DIY, Do it yourself, guide, guitar, how to make PVC multiple guitar rack, Make, pvc, rack, Stand, Tutorial, walkthrough

INTRODUCTION

Mission

Unwilling to pay the $80 – $100 for a guitar rack made in China, I searched for a cheap do it yourself answer. The goal was to get parts from a local hardware store and put a guitar rack for multiple guitars together for less than $20. After scouring the internet, the guides I found were less than satisfactory. So I went on a mission to design and make the ultimate multiple guitar PVC guitar rack. Here is is a guide…

Completed Guitar Stand

I did it! I finished the guitar stand with the three elbows I needed, then gave it to my brother (he was very happy).

Posted by Technomancer at 3:23 PM

Rain Alarm

Nov.24, 2010 in New Circuits

GIVES BEEP WHEN WATER IS IN CONTACT WITH THE WIRE

Water is a conductor of electricity. When water is in contact with the probe then there is a flow of current which reaches to the base of Q1. Transistor Q1 is a NPN transistor which conducts. With the conduction of Q1 electron reaches to Q2 which is a PNP transistor .Q2 also conducts and current flows through the speaker. In a speaker there is inductive coil which causes motion in one direction and also produce induce current which is in opposite direction to the flow of current this induce current in the form of pulse flows through a capacitor, resistance and switches off Q1 and relax .this process repeats again and again till probe is in contact with water or we can say there is a oscillation in the circuit thus speaker diaphragm vibrates and gives a tone. Frequency of the circuit depends on the value of Speaker Coil impendence, Capacitor and Resistance Value.

Circuit Diagram of Rain Alarm