Forum Diagram: alarm

Showing posts with label alarm. Show all posts

Friday, November 14, 2014

SENSITIVE OPTICAL BURGLAR ALARM

This optical burglar alarm uses two 555 timer ICs (IC1 and IC2). Both the ICs are wired as astable multivibrators. The first astable multivibrator built around IC1 produces low frequencies, while the second astable multivibrator built around IC2 produces audio frequencies.General-purpose Darlington photo-transistor T1 is used as the light sensor. To increase the sensitivity of the circuit, NPN transistor T2 is used.

Place phototransistor T1 where light falls on it continuously. Phototransistor T1 receives light to provide base voltage to transistor T2. As a result, transistor T2 conduct to keep reset pin 4 of IC1 at low level. This disables the first multivibrator (IC1) and hence the second multivibrator (IC2) also remains reset so the alarm (LS1) does not sound.

Circuit Diagram

When light falling on Darlington phototransistor T1 is obstructed, transistor T2 stops conducting and reset pin 4 of IC1 goes high. This enables the first multivibrator (IC1) and hence also the second multivibrator (IC2). As a result, a beep tone is heard from speaker LS1. The beep rate can be varied by using preset VR1, while the output frequency of IC2 can be varied by using another preset VR2.

This circuit works off a simple 6V-12V DC power supply.

Parts List

Resistors (all ¼-watt, ± 5% Carbon unless stated otherwise)

R1, R5 = 1 KΩ

R2 = 100 KΩ

R3 = 4.7 KΩ

R4 = 10 KΩ

VR1 = 1 MΩ

VR2 = 100 KΩ

Capacitors

C1 = 1 µF/16V

C2 = 0.01 µF

C3 = 0.047 µF

C4 = 0.01 µF

C5 = 47 µF/25V

Semiconductors

IC1, IC2 = NE555

T1 = 2N5777 Photo Transistor

T2 = BC547

LED1 = RED LED

Miscellaneous

LS1 = 8Ω / 0.5W

Sunday, November 2, 2014

BURGLAR ALARM USING IC TIMER 555 556 ELECTRONIC DIAGRAM

BURGLAR ALARM USING IC TIMER 555/556 ELECTRONIC DIAGRAM

circuit diagram of burglar alarm using IC timer 555/556 is functioned as an alarm to prevent thief entering your house. The alarm would produce loud sound when a thin wire connecting resistor R1 with IC pin no 4 is broken. Thin fiber is used as the wire. The thinner the wire, the more responsive the alarm. This circuit needs 5-15V power supply, buzzer is used as a speaker. Here is the circuit schematic :

Parts list :

Resistor R1 : 10k
Resistor R2 : 68k
Resistor R3 : 1k
Polar capacitor C1 : 1uF/15 B
Capacitor C2-C3 : 0.01uF
IC Timer : NE555

Thursday, October 2, 2014

Tilt Sensor Alarm Circuit

This is a design for simple circuit of the tilt sensor alarm presented here can be fabricated using readily available inexpensive components. The circuit is a true transistor based design. Home made Tilt sensor for this circuit is an ordinary little glass/plastic bottle with two metal needles inserted through its cap, and a small quantity of water inside. A 9V alkaline battery is enough for powering the whole circuit. Here’s the figure of the schematic circuit;

In this figure shows that this circuit is based on two transistor as main control. There are BC 557 and BC 547. Usually, transistor T1 is in inactive state. When the sensor assembly is tilted, both needles inside the sensor (bottle) are short circuited by the water and a positive voltage is available at the base of T1 and it becomes active. Activation of T1 causes the activation of next transistors T2 and T3. After this, T2 supplies constant bias for T1 to make it latched and T3 triggers the SCR(T4) which in turn energizes the active piezo-sounder(BZ1). Once activated the circuit can be deactivated by depressing the power/reset switch S1. Preset pot P1 is deliberately added here to adjust the circuit sensitivity. This may become necessary if you are trying a different (readymade) tilt sensor. Similar, SCR(T4) and piezo sounder (BZ1) may be replaced with near equivalent parts. Resistor R3 (100-150 Ohm) is optional.

Tuesday, September 16, 2014

Overheat Detector Alarm Switch

At the heart of this circuit is a precision integrated temperature sensor type LM35 (IC1), which provides an accurately linear and directly proportional output in mV, over the zero to +155 degrees C temperature range. The LM35 develops an output voltage of 10 mV/K change in measured temperature. Designed to draw a minimal current of its own, the LM35 has very low self heating in still air. Here the output of the LM35 is applied to the non-inverting input of a comparator wired around a CA3130 opamp (IC2). A voltage divider network R3-P1 sets the threshold voltage, at the inverting input of the opamp. The threshold voltage determines the adjustable temperature trip level at which the circuit is activated.

Circuit diagram:

Overheat Detector Alarm/Switch Circuit Diagram

When the measured temperature exceeds the user-defined level, the comparator pulls its output High to approx. 2.2 V causing transistor T1 to be forward biased instantly. T2 is also switched on, supplying the oscillator circuit around IC3 with sufficient voltage to start working. The 555 set up in astable mode directly drives active piezoelectric buzzer Bz1 to raise a loud alert. Components R7, R8 and C4 determine the on/off rhythm of the sounder. A transistor based relay driver may be driven off the emitter of T1 (TP1). Similarly, replacing the piezo sounder with a suitable relay allows switching of high-power flashers, sirens or horns working on the AC mains supply.

Author: T. K. Hareendran - Copyright: Elektor Electronics 2007

Saturday, September 13, 2014

Morning Alarm Wiring diagram Schematic Using LDR

Description

Circuit showing a morning alarm.Here we have used a switching transistor.When the sun rise up ldr is low resistance so the ldr is conduct and a positive volt coming to the base of the Q1 there for the transistor will switch.This time the buzzer is ON . Adjust the preset control the intensity of light.Manually cut off the power.Are you interested please comment and join this site

Component Required

Resistor 4.7k preset , LDR

Transistor BC 548

Buzzer

Wednesday, September 10, 2014

Simple C O alarm to foil P S Wiring diagram Schematic

This is a simple Capacitance operated alarm to foil purse snatchers. As long as touch plates (1) are touched together, the alarm is off. If not held for about 30 seconds, the alarm goes off. The schema can be disabled with switch or by touching the plates (2) The alarm is battery operated by a bicycle horn.

Simple C-O alarm to foil P S Circuit Diagram

Saturday, August 30, 2014

Simple Light Sensor Alarm circuit with NE555

This schema sent out an alarm when its LDR sensor is exposed to light by sun or lamp. A 555 astable multivibrator was used here which sent signal a tone of about 1kHz upon detecting light.The sensor when exposed by light completes the schema and makes the 555 oscillate at about 1kHz with transistor to drive current.

The sensor is also shown in the schema diagram. It has to placed making an angle of about 30 – 45 degrees to the ground.

Sensitivity can be adjust with P1. This makes the sun light to flow through it to the ground and prevents the alarm from going on due to the stored light on the sensor.

Tuesday, August 26, 2014

Motorbike Alarm Wiring diagram Schematic

This simple to build alarm can be fitted in bikes to protect them from being stolen. The tiny schema 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 schema 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 schema. 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 schema. 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 schema. 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.

Streamdiagram

Monday, August 25, 2014

Car Burglar Alarm Circuit

This is a burglar alarm for cars.If some one opened the car door.The alarm will activate.Normally this schema provides 5 second to open the door and close it but If somebody opened it more than that the alarm will activate.To turn the schema on S1 should be closed.If you want to open the door more than 5 seconds.You can deactivate the alarm by using S2.Exit delay time can be adjusted by using R1 and C1.

Note

# This schema operates with 9v power supply
# Be careful when you work with high amp batteries

Sunday, August 17, 2014

Fridge Door “Open!” Alarm

This schema produces an audible alarm when fridge is left open for a preset time.This versatile alarm is based on two 555 timer IC’s.Both ICs are wired as astable Multivibrators.

An LDR is connected in parallel to the timing capacitorC1 of IC 1.When door is completely close there will be no light inside the fridge and LDR offers high resistance keeping R1 fully charged.When door is left open ,the lamp inside the fridge will remain glown ,LDR will be illuminated,and its resistance falls.This makesC1 stop charging and starts to discharge ( In simple words ,this is because at low resistance LDR bye passes much of the current in the parrallel path and capacitor gets less current).Now IC 1 starts slightly oscillating and after a preset time of 25 ( time T1) seconds its output goes high.This out put makes the Ic 2 to produce oscillations and results in a beeping sound for next 20(time T2) seconds and cycle is repeated till door is closed.

Notes .

Assemble the schema on a good quality PCB .Time T1 & T2 can be adjusted by varying C1, C2, R1, R4 etc (Refer data sheet of 555).Place the LDR close enough to the lamp inside the fridge.

Parts List.

R1_____________10K 1/4W Resistance
R3_____________2.2 M 1/4W Resistance
R4_____________1M 1/4W Resistance

C1_____________10µF 25V Electrolytic Capacitance
C2_____________100nF 63V Polyester Capacitance

D1____________ 1N4001 Diode

IC1,IC2_________NE 555 Timer ICs

BZ1___________ Piezo Buzzer

B1____________ 3V Cell

Friday, August 15, 2014

Build a Parallel Loop Alarm Wiring diagram Schematic

Build a Parallel Loop Alarm Circuit Diagram. Two SCRs are used with two sensor loops. One loop uses series switches, the other loop parallel switches. When a switch actuation occurs, the SCR triggers.The alarm should be a non interrupting type.

Parallel Loop Alarm Circuit Diagram

Thursday, August 14, 2014

Cmos Motorcycle Alarm Wiring diagram Schematic

This Simple Cmos Motorcycle Alarm Circuit Diagram features an intermittent siren output and automatic reset. It can be operated manually using a key-switch or a hidden switch; but it can also be wired to set itself automatically when you turn-off the ignition. By adding external relays you can immobilize the bike - flash the lights etc.

Cmos Motorcycle Alarm Schematic Diagram

Notes

Any number of normally-open switches may be used. Fit "tilt" switches that close when the steering is moved or when the bike is lifted off its side-stand or pushed forward off its centre-stand. Use micro-switches to protect removable panels and the lids of panniers etc.

Once activated - the rate at which the siren switches on and off is controlled by R9 & C5. For example - increasing the value of C5 will slow it down - while reducing the value of R9 will make it faster.

While at least one switch remains closed the siren will sound. About thirty seconds after all of the switches have been opened, the alarm will reset. How long it takes to switch off depends on the characteristics of the actual components used. You can adjust the time to suit your requirements by changing the value of R6 and/or C4.

The schema is designed to use an electronic Siren drawing 300 to 400mA. Its not usually a good idea to use the bikes own Horn because it can be easily located and disconnected. However, if you choose to use the Horn, remember that the alarm relay is too small to carry the necessary current. Connect the coil of a suitably rated relay to the "Siren" output. This can then be used to sound the Horn - flash the lights etc.

The schema board and switches must be protected from the elements. Dampness or condensation will cause malfunction. Connect the 1-amp in-line fuse AS CLOSE AS POSSIBLE to your power source. This is VERY IMPORTANT. The fuse is there to protect the wiring - not the alarm. Exactly how the system is fitted will depend on the make of your particular machine - so Im unable to provide any further help or advice in this regard.

The quiescent (standby) current of the schema is virtually zero - so there is no drain on the battery. If you want to operate the alarm manually use a key-switch or a hidden switch connected to the "off/set" terminals. For automatic operation connect a wire from the ignition schema to the "ignit" terminal. Then every time you turn-off the ignition - the alarm will set itself. Remember that this wire from the ignition switch is not protected by your 1-amp inline fuse. So unless its run is very short - fit the wire with its own 1-amp fuse as close as possible to its source.

When you set the alarm - if one of the switches is closed - the siren will sound. This could cause annoyance late at night. A small modification will allow you to Monitor The State Of The Switches using LEDs. When the LEDs are all off - the switches are all open - and its safe to turn the alarm on.

Veroboard Layout

Wednesday, August 13, 2014

Light sensetive alarm circuit

This is light sensitive schema diagram.You can use this schema for various things.here when the light fall on LDR it will indicate by an alarm.

Tuesday, August 12, 2014

5 Digit Alarm Control keypad Wiring diagram Schematic

This Simple 5 Digit Alarm Control keypad Circuit Diagram switch will suit the Modular Burglar Alarm schema.However, it also has other applications. The Keypad must be the kind with a common terminal and a separate connection for each key. On a 12-key pad, look for 13 terminals. The matrix type with7 terminals will NOT do. Choose the five keys you want as your code, and connect them to `A, B, C, D & E`.

5 Digit Alarm Control keypad Circuit Diagram

Wire the common to R1 and all the remaining keys to `F`. Because your choice can include the non-numeric symbols, almost 100 000different codes are available. The Alarm is set using the first four of your five chosen keys. When `A, B, C & D` are press edin the right order and within the time set by C1 and R2 (about10 seconds), current through R11 switches Q6 on. The relay energizes, and then holds itself on by providing base current forQ6 through R12.

The 12-volt output switches from the “off” to the “set ” terminal, and the LED lights. To switch the Alarm off again it is necessary to press A, B, C, D & E in the right order. The IC is a quad 2-input AND gate, a Cmos 4081.These gates only produce a high output when both inputs are high.Pressing `A` takes pin 1 high for a period of time set by C1 andR2. This `enables` gate 1, so that when `B` is pressed, the output at pin 3 will go high. This output does tw1o jobs. It locks itself high using R3 and it enables gate 2 by taking pin 5high.

The remaining gates operate in the same way, each locking itself on through a resistor and enabling its successor. If the correct code is entered within the time allowed, pin 10 will switch Q5 on and so connect the base of Q6 to ground. This causesQ6 to switch off and the relay to drop out. Any keys not wired to `A, B, C, D or E ` are connected to the base of Q4 byR9. Whenever one of these `wrong` keys is pressed, Q4 takes pin 1low. This removes the `enable` from gate 1, and the code entry process fails. If C, D or E is pressed out of sequence, Q1, Q2 orQ3 will also take pin 1 low, with the same result.

You can change the code by altering the keypad connections. If you make a mistake entering the code, just start again. If you need a more secure code you can use a bigger keypad with more `wrong`keys wired to `F`. A 16-key pad gives over half a million different codes. All components are shown lying flat on the board; but some are actually mounted upright. The links are bare copper wires on the component side. tw1o of the links must befitted before the IC.