Schematic Diagram: alarm

Showing posts with label alarm. Show all posts

Thursday, November 13, 2014

Burglar Alarm Using LDR and BC 548

Description Circuit showing a Burglar Alarm.Here we have used a ldr and a switching transistor for making this circuit
.When the light coming towards the ldr during the period the ldr have low resistance so the buzzer will on.When the light going away the ldr during the period the ldr have high resistance so the transistor will off.Here you need a 12 volt power supply

Components Required Resistor

10 k(preset)

Transistor
BC 548

LDR
Buzzer

Source by : http://www.electronics-circuits.in/2012/03/burglar-alarm-ldr-bc-548.html

Friday, November 7, 2014

Motorbike Alarm

This simple to build alarm can be fitted in bikes to protect them from being stolen. The tiny circuit can be hidden anywhere, without any complicated wiring. Virtually, it suits all bikes as long as they have a battery. It doesnt drain out the battery though as the standby current is zero. The hidden switch S1 can be a small push-to-on switch, or a reed switch with magnet, or any other similar simple arrangement. The circuit is designed around a couple of low-voltage MOSFETs configured as monostable timers. Motorbike key S2 is an ignition switch, while switch S3 is a tilt switch. Motorbike key S2 provides power supply to the gate of MOSFET T2, when turned on.

When you turn ignition off using key S2, you have approximately 15 seconds to get off the bike; this function is performed by resistor R6 to discharge capacitor C3.

Thereafter, if anyone attempts to get on the bike or move it, the alarm sounds for approximately15 seconds and also disconnects the ignition circuit. During parking, hidden switch S1 is normally open and does not allow triggering of mosfet T1. But when someone starts the motorbike through ignition switch S2, MOSFET T2 triggers through diode D1 and resistor R5. Relay RL1 (12V, 2C/O) energises to activate the alarm (built around IC1) as well as to disconnect the ignition coil from the circuit. Disconnection of the ignition coil prevents generation of spark from the spark plug. Usually, there is a wire running from the alternator to the ignition coil, which has to be routed through one of the N/C1 contacts of relay RL1 as shown in Fig.1 Fig.2 shows the pin configurations of SCR BT169, MOSFET BS170 and transistor BC548.

Circuit diagram :

Motorbike Alarm Circuit Diagram

Motorbike Alarm-Pin Configurations :

Pin configurations of BT169, BS170 and BC548

Also, on disconnection of the coil, sound generator IC UM3561 (IC1) gets power supply through N/O2 contact of relay RL1. This drives the darlington pair built around T3 and T4 to produce the siren sound through loudspeaker LS1. To start the vehicle, both hidden switch S1 and ignition key S2 should be switched on. Otherwise, the alarm will start sounding. Switching on S1 triggers SCR1, which, in turn, triggers MOSFET T1. MOSFET T1 is configured to disable MOSFET T2 from functioning. As a result, MOSFET T2 does not trigger and relay RL1 remains de-energised, alarm deactivated and ignition coil connected to the circuit. Connection to the ignition coil helps in generation of spark from the spark plug. Keeping hidden switch S1 accessible only to the owner prevents the bike from pillaging.

Tilt switch S3 prevents attempt to move the vehicle without starting it. Glass-and metal-bodied versions of the switch offer bounce-free switching and quick break action even when tilted slowly.

Unless otherwise stated, the angle by which the switch must be tilted to ensure the contact operation (operating angle), must be approximately 1.5 to 2 times the stated differential angle. The differential angle is the measure of the just closed position to the just open position. The tilt switch has characteristics like contacts make and break with vibration, return to the open state at rest, non-position sensitivity, inert gas and hermetic sealing for protection of contacts and tin-plated steel housing. If you find difficulty in getting the tilt switch, you may replace it with a reed switch (N/O) and a piece of magnet. The magnet and the reed switch should be mounted such that the contacts of the switch close when the bike stand is lifted up from rest.

Sunday, September 21, 2014

Alarm Equipped Digital Clock LM5860 circuit and explanation

The LM8560 is alarm equipped digital clock Integrated Circuit with built-in driver capable of directly driving LED display equipment. As Intehrated Circuit himself the VDD pin for the LM8560 is graded to withstand a voltage of 15V.

LM8560 digital clock circuit has many features like:

Single chip P-channel ED MOS LSI.
LED direct drive using time division (duplex configuration).
Wide operating power supply voltage range.
Built-in alarm function with 24-hour control.
Supports changeover between 12-hour AM/PM and 24-hour displays
Built-in battery backup CR oscillator.
Built-in automatic fast forward function for hour and minute settings.
Built-in sleep timer function (maximum intervals of 59 minutes or 1 hours and 59 minutes).
Built-in snooze function supporting repeat use.
Equipped with power failure display function.
900Hz output for alarm tone .

Using LM8560 circuit you will have many advantages , because of integration in one package of all features you can use it in small clock alarm radio circuits or in a simple clock alarm circuit. For LM 8560 clock alarm circuit you can use a positive or negative power supply maximum 15 volts.

Thursday, September 18, 2014

Simple Home Alarm System Home Alarm System

Simple Home Alarm System

This Home Alarm System is simple, secure, fast and cheap. Its only few components with maximum security with Rolling Code TX and Shock Sensor with variable sensitivity. The alarm module can be assembled in only 2 hours and it dont need manual preset.

Home Alarm System with this characteristics is the most cheap system and the total cost could be reduced using a normal external sounder (escl. AG8).GSM module will be add in the future for a remote control.

The blue led connected to the pin RA3 of micro controller is used like a memory to know if the home alarm system has been activated by an event and its reset after a reactivation. The red led connected to the power supply before the 1N5406 diode is used to check the power supply connection. Of course the other 3 micro led red near the relays are used to check the output state.

Here you can download the last version of The Home Alarm System date 10 July 2007:

source
binary (hex)

Sunday, September 14, 2014

Mains Supply Failure Alarm

Whenever AC mains supply fails, this schema alerts you by sounding an alarm. It also provides a backup light to help you find your way to the torch or the generator key in the dark. The schema is powered directly by a 9V PP3/6F22 compact battery. Pressing of switch S1 provides the 9V power supply to the schema. A red LED (LED2), in conjunction with zener diode ZD1 (6V), is used to indicate the battery power level.

Resistor R9 limits the operating current (and hence the brightness) of LED2. When the battery voltage is 9V, LED2 glows with full intensity. As the battery voltage goes below 8V, the intensity of LED2 decreases and it glows very dimly. LED2 goes off when the battery voltage goes below 7.5V. Initially, in standby state, both the LEDs are off and the buzzer does not sound. The 230V AC mains is directly fed to mains-voltage detection optocoupler IC MCT2E (IC1) via resistors R1, R2 and R3, bridge rectifier BR1 and capacitor C1.

Illumination of the LED inside optocoupler IC1 activates its internal phototransistor and clock input pin 12 of IC2 (connected to 9V via N/C contact of relay RL1) is pulled low. Note that only one monostable of dual-monostable multivibrator IC CD4538 (IC2) is used here. When mains goes off, IC2 is triggered after a short duration determined by components C1, R4 and C3. Output pin 10 of IC2 goes high to forward bias relay driver transistor T1 via resistor R7.

Mains Supply Failure Alarm Circuit Diagram

Relay RL1 energises to activate the piezo buzzer via its N/O contact for the time-out period of the monostable multivibrator (approximately 17 minutes). At the same time, the N/C contact removes the positive supply to resistor R4. The time-out period of the monostable multivibrator is determined by R5 and C2. Simultaneously, output pin 9 of IC2 goes low and pnp transistor T2 gets forward biased to light up the white LED (LED1).

Light provided by this back-up LED is sufficient to search the torch or generator key. During the mono time-out period, the schema can be switched off by opening switch S1. The ‘on’ period of the monostable multivibrator may be changed by changing the value of resistor R5 or capacitor C2. If mains doesn’t resume when the ‘on’ period of the monostable lapses, the timer is retriggered after a short delay determined by resistor R4 and C3.

Source: EFY Mag

Saturday, September 13, 2014

CAR ALARM REMOTE CAR STARTERS

Car alarm is an electronic device installed in a vehicle (car, truck, boat, motorcycle) in an attempt to discourage theft of the vehicle itself, its contents, or both. Alarms work by emitting high-volume sounds (usually a siren, Klaxon, pre-recorded verbal warning, the vehicles own horn, or a combination thereof) when the conditions necessary for triggering are met, as well as by flashing some of the vehicles lights, and (optionally) notifying the cars owner via a paging system and interrupting various electrical circuits necessary for the car to start.

Many Poeple get confused between an alarm and immobilizer. An immobilizer is an electronic device fitted to an automobile which prevents the engine from running unless the correct key (or other token) is present. This prevents the car from being "hot wired" after entry has been achieved.

Car Alarm Advantages:

Having an expensive aftermarket system in a car without an alarm is asking for trouble. Ive heard too many stories of people learning the hard way and losing a lot of money when they find out that their aftermarket audio system was not covered by their insurance. Car alarms may not be able to stop the thief but they do attract a lot of attention to the thiefs activities. Besides having an alarm system, here are a few other pieces of advice to keep your systems in a safe place.

* Dont drive through neighborhoods blasting the bass and calling attention to your system. Not only is this a courtesy to the residents but it also keeps the local hoods from scoping your ride as their next target.

* When parking your vehicle, try to park under lights and in an area where it is not hidden from view. Keeping it in the open reduces your chance of a thief breaking in to it. Thieves hate to be seen.

* Try to keep areas within the vehicle looking as stock or stealth as possible. Large aftermarket grilles are a nice advertisement that you have more than OEM equipment. Try to concentrate style in areas that are hidden from the exterior view, such as in the trunk.

Car Alarm Types:

There are two main types of car alarm activation methods. Passive and active. Passive alarms automatically enter an armed state after the ignition is turned off and the last door is closed. Active alarms require the user to press the transmitter button to arm and disarm the system. If you set your alarm to arm passively you can probably get a discount on your insurance. Check with your insurance provider. You may get a discount either way. Most good alarm systems can be configured as passive or active arming.

An alarm system should be put in at the same time or before a stereo system is put in. By waiting until after the system is in you run the risk of having it stolen before the alarm is installed.When shopping for an alarm, dont be cheap. A good quality unit can be purchased for about a hundred dollars if you shop around. For two hundred dollars you should get an alarm with some extensive features built in. Installation for the car alarm will run about one hundred dollars and up depending on how many extra features that you want hooked up and how fancy you want the installation to look. Keep the appearance on at least the same level as the stereo system, especially if you plan on competing in car sound off competitions.

If you want to install your own car alarm or remote car starters, make sure you read the manual carefully.

Car Alarm Features:

There are probably more features available on a car alarm than any other single category of equipment available for your system. There are new features constantly popping up on the market. Here are some of the most common.

Active Re-arm: After the alarm has been disarmed the system will automatically re-arm after a specified amount of time if a door is not opened. This is to prevent accidental disarming by the remote transmitter.

Air Horns: These are used on the interior or exterior to call more attention and cause pain to the thief if he makes it into the interior of the vehicle.Anti-Code Grabbing: A method employed to change the alarm code with every arm/disarm. The purpose of which is to defeat code grabbing equipment that can capture and resend your code to disarm the alarm at the thiefs leisure.

Friday, August 29, 2014

Refrigerator Door Alarm Wiring diagram Schematic

Do your kids leave the door to the refrigerator open? Or does your celery reach out to keep the door from closing properly when you turn your back? Heres a simple schema that beeps whenever the door is open for an extended period of time (which will also put a little pressure on the fridge loiterers in the house).

Simple Refrigerator Door Alarm Circuit Diagram

The photocell has a very high resistance in the dark which drops very low when the door opens and the light turns on. The 22 uF capacitor begins to charge and when the voltage reaches the zener voltage, the beeper sounds. Closing the door allows the capacitor to discharge through the 10 meg. resistor, resetting the beeper. The schema draws very little power when the door is shut and only draws significant current when the beeper is sounding. The transistor may be a single NPN darlington such as the MPS-A14 or two 2N4401s connected as shown. Other types will also work. The delay may be changed by changing the value of the capacitor. It may be a good idea to add a 10 uF capacitor across the battery.