Alarm Control

General Purpose Alarm Circuit for Resistive Sensor circuit

Published:2013-3-29 4:35:00 Author:Ecco | Keyword: General Purpose Alarm , Resistive Sensor

When the resistance value of a temperature, light, pressure, or any other resistive sensors Rs drops below a certain point (adjusted by a preset potentiometer), the SCR (silicon controlled switch) will be triggered. The sensor (Rs) and the potentiometer placement can be interchanged to get opposite action, where the SCR need to be triggered at the increase of sensing resistor (Rs). Here is the schematic diagram of the circuit:   (View)

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Arduino Panic Alarm

Published:2013-3-27 4:16:00 Author:Ecco | Keyword: Arduino Panic Alarm

Panic Alarm circuit consists of two equally important parts. The first part is the ready-made Arduino Microcontroller board, and the second part is an interface circuit which can be wired on a piece of prototyping board. You can use any standard 9V battery to power the whole circuit, and the Push-ON (push ‘n’ hold) switch (S1) to activate the alarm function. An additional Electro-Magnetic Relay (EMR) is also attached to the interface circuit.   (View)

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Touch Alarm System

Published:2013-3-25 4:25:00 Author:Ecco | Keyword: Touch Alarm System

Touch Alarm circuit is widely used for security, which is installed on the door. The advantages of this alarm is because the cost is cheap and difficult to detect by burglars / intruders.   (View)

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Easy Build Motorcycle Alarm

Published:2013-3-25 4:16:00 Author:Ecco | Keyword: Easy Build Motorcycle, Alarm

The following circuit is a simple, cheap and easy build motorcycle alarm. The circuit just required 2 transistors to drive the relay the the relay act as a switch to activate the buzzer. Any number of normally-open switches may possibly be applied.   (View)

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Electronic Siren based NE555

Published:2013-3-25 4:04:00 Author:Ecco | Keyword: Electronic Siren

Here the circuit diagram of electronic siren based NE555. This circuit produces a sound like factory siren. It applies a 555 timer IC which is utilized as an astable multivibrator of a center frequency of about 300Hz. The frequency is controlled by the pin 5 of the IC.   (View)

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Pyroelectric Fire Alarm System

Published:2013-3-25 4:02:00 Author:Ecco | Keyword: Pyroelectric , Fire Alarm System

This is definitely an ultra-sensitive fire sensor that exploits the direct piezoelectric property of an ordinary piezo component to recognize the fire. The lead zirconate titanate crystals within the piezo component have the property to deform and produce an electrical potential when heated, thus converting the piezo component into a heat sensor.   (View)

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Multitone Siren Alarm

Published:2013-3-25 4:01:00 Author:Ecco | Keyword: Multitone Siren Alarm

Here the simple schematic of multitone siren alarm circuit. This multitone siren is effective for reverse horns, burlgar alarms, and many others. It generates five various audio tones and is much more earcatching than a single-tone siren.   (View)

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Fire Alarm with LDR Sensor

Published:2013-3-25 3:48:00 Author:Ecco | Keyword: Fire Alarm , LDR Sensor

This is the fire alarm circuit which use LDR to sense the smoke from the fire, so it can be used to detect any dark smoke. With the onset of summer season, possibilities of fire accidents go up. These fire accidents could be prevented if timely alarms are available. The circuit given right here alerts the user against these fire accidents.   (View)

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Cheap Motorcycle Alarm

Published:2013-3-25 3:47:00 Author:Ecco | Keyword: Cheap Motorcycle Alarm

This is simple to build and cheap motorcycle alarm circuit which could be fitted in motorcycles to take care of them from getting stolen. The tiny circuit may be hidden anyplace, without having any difficult wiring. Practically, it fits all motorcycles as long as they’ve a electric battery.   (View)

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Power Supply Failure Alarm

Published:2013-3-25 3:44:00 Author:Ecco | Keyword: Power Supply, Failure Alarm

This is the ‘special’ circuit design of power supply failure alarm. The vast majority of the power supply failure alarm / indicator circuits require a independent power supply for themselves. However the alarm circuit introduced right here requires no extra supply power source.   (View)

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Notebook Anti Theft Protector

Published:2013-3-25 3:43:00 Author:Ecco | Keyword: Notebook, Anti Theft Protector

Here the notebook anti theft protector circuit to secure your important netbook / notebook from stealing. Basically, this is a mini security alarm generator. Fixed inside the notebook case, it will definitely sound a noisy alarm when a person attempts to grab the notebook. This very sensitive circuit utilizes a homemade tilt switch to turn on the alarm system through tilting of the laptop computer case.   (View)

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RAIN ALARM Circuit

Published:2013-3-5 20:39:00 Author:Ecco | Keyword: RAIN ALARM

This circuit consumes no current until moisture is detected on the rain plate.   (View)

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DUMMY ALARM Circuit

Published:2013-3-4 21:48:00 Author:Ecco | Keyword: DUMMY ALARM

This Dummy Alarm project makes an LED flash briefly once every 5 seconds to imitate the indicator light of a real alarm. Overview The circuit is designed to use very little current to prolong battery life so that it can be left on permanently. An on/off switch is not included, but could be added if you wish. The 7555 timer IC used is a low power version of the standard 555 timer. A 憇uperbright?red LED is used because this provides a bright flash with a low current. The LED is off for most of the time so the average total current for the circuit is less than 0.2mA. With this very low current a set of 3 alkaline AA cells should last for several months, maybe as long as a year.   (View)

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The detection and alarm device circuit with laser rod

Published:2013-2-19 1:00:00 Author:Ecco | Keyword: detection , alarm device, laser rod

Analog sound ICs form a receiving circuit, usually the laser emitted by laser rod is irradiated on photoresistor RG, RG shows low resistance, the transistor VT1 is cut-off because of base's low potential, then IC does not work, speaker Y does not emit sound. Once a person or object comes into the alert zone, RG resistance increases due to the less than light, VT1 base potential rises to get saturated conduction, then IC is energized.   (View)

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Multi-channel laser burglar alarm circuit

Published:2013-2-17 21:00:00 Author:Ecco | Keyword: Multi-channel laser, burglar alarm

VT1, VT2, RL1, RP1, R1, K and VD6 constitute light control switch, in the daytime, photoresistor RL1 is in a low resistance state, VT1 gets saturated conduction, VT2 is turned off, K relay is not energized, normally open contact J is in a disconnected state, the alarm circuit does not work; at night, RL1 becomes high impedance, VT1 is deadline, VT2 gets saturated conduction, K gets electrical to make J pull in, then the circuit supplies for the whole machine, red light-emitting diode is lit.   (View)

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Timer alarm circuit using NE555

Published:2012-12-12 2:52:00 Author:Ecco | Keyword: Timer alarm

Timer alarm circuit using NE555 is shown as the figure.   (View)

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Alarm circuit diagram using pyroelectric sensor

Published:2012-12-11 0:04:00 Author:Ecco | Keyword: Alarm , pyroelectric sensor

The circuit is composed of amplifier, comparator and an output control part. According to Faraday's law, person's body temperature is about 37 ℃, radiation infrared wavelength is about 10μm, the pyroelectric sensor selects P7178 with 7 ~ 20μm sensitive wavelength range. A1 and A2 are selected low noise, low loss CMOS op amp μPC358, and it is connected to band-pass filter composed of RC to prevent the entry of the noise and error signal, extracting only a signal when the human body moves. A3 and A4 constitute a comparator.   (View)

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High sensitivity anti-theft alarm circuit with high loudness

Published:2012-12-2 21:28:00 Author:Ecco | Keyword: High sensitivity, anti-theft alarm, high loudness

The SCR, R2 and L form a triggered power switch with controllable disconnection, L is an anti-theft wire. Transistor VT and IC1 form approximately 2min monostable delay trigger circuit. IC2 is the language alarm circuit which can emit the sound of catch thief, please . Usually when K is closed, if there is no thief, the alarm burglar lines will make SCR control gate trigger current be short, SCR is off, the circuit does not work, and it is in the probation status. If thied jumps over the wall of park, the wire L is pulled and disconnected, SCR control pole gets triggered current by R2, then it is be turned on to provide the power for working circuit.   (View)

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The roadblocks flashing alarm circuit ( 4 )

Published:2012-11-5 20:48:00 Author:Ecco | Keyword: roadblocks flashing, alarm

Road blocks flashing warning light using battery is shown in the figure, and it can be used local road facilities without AC power for roadblocks alarm. NE555, RP1 , RP2 , C1 , RL and RL form a a light -controlled self-excited multivibrator. Due to light exposure in daytime, it is in low resistance, NE555 forces reset terminal ④ feet level to be less than 0.4V, and the NE555 is mandatory reset, output end ③ feet is constant low, then VT1 and VT2 are cutoff, warning lights E does not shine. Due to RL has no light exposure in nighttime, it shows a high resistance, then it is divided by RP2 to make ④ feet level increase, when it is greater than 0.4V, you can lift the blockade on the circuit, the circuit is start-up.   (View)

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Open circuit, short circuit anti-theft alarm

Published:2012-10-31 21:00:00 Author:Ecco | Keyword: Open circuit , short circuit , anti-theft alarm

It uses AC driver to make higher light power output by the light emitting diode, the driver circuit is shown in Figure. The two LEDs are connected reversely in parallel, so that the power's positive and negative half-cycle can be dispalyed by a light-emitting diode.   (View)

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