Simple Fire Alarm Circuit
Here is a simple fire alarm circuit based on a LDR and lamp pair for sensing the fire.The alarm works by sensing the smoke produced during fire.The circuit produces an audible alarm when the fire breaks out with smoke.
When there is no smoke the light from the bulb will be directly falling on the LDR.The LDR resistance will be low and so the voltage across it (below .6V).The transistor will be OFF and nothing happens.When there is sufficient smoke to mask the light from falling on LDR, the ....etc

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respected sir,
I want to build a mini robot having a bulldozer arm controlled by joystick for taking part in robot wars in our college..sir i want ckt diag bcs i want to implement by myself..
sir, I want to build a mini robot having a bulldozer arm controlled by joystick for taking part in robo wars in our college..sir i want the ckt diag bcs i want to implement myself..my email id is:[email protected] am eagerly waiting for ur rply.. ....etc

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In the past, hardwired alarm systems are the only choice for customers who need security equipment to protect premises. Today, with rapid technology evolve, many users shift from hardwired alarm to wireless alarm. It seems home security industry is moving from hardwired to wireless, but as one of mature and stable alarm equipment, some users still favor the hard wired alarm system. In this article, we will show you some basic information about advantages and disadvantages of hardwired alarm systems.

What s hardwired alarm system ?

Alarm ....etc

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Many fire alarm circuits are presented here,but this time a new circuit using a thermistor and a timer to do the trick. The circuit is as simple and straight forward so that, it can be easily implemented. The thermistor offers a low resistance at high temperature and high resistance at low temperature. This phenomenon is employed here for sensing the fire.

The IC1 (NE555) is configured as a free running oscillator at audio frequency. The transistors T1 and T2 drive IC1. The output (pin 3) of IC1 is couples to base of transistor T3 (SL100), w ....etc

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project about tank water level indicator with overflow alarm circuit ppt in to the right box for getting free material and support from us/dedicated premium members.. ....etc

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simple touch alarm circuit using ic 555 ppt

Touch the sensor of the alarm with your finger and it starts beeping, goes on for some time and then stops. Touching it again, and it goes again! This little and flexible circuit consists of a touch sensor and a directly coupled transistor amplifier with a small loudspeaker as the output load. Two sensor strips of metal are mounted side by side on a 1 1 cm size micasheet and connected to the input of the circuit.

How the touch alarm works

Under normal conditions no current flows through switching ....etc

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panic alarm

A panic alarm is an electronic device designed to assist in alerting somebody in emergency situations where a threat to persons or property exists.
A panic alarm is frequently but not always controlled by a concealed panic alarm button. These buttons can be connected to a monitoring center or locally via a silent alarm or an audible bell/siren. The alarm can be used to request emergency assistance from local security, police or emergency services. Some systems can also activate closed-circuit television to record or assess the e ....etc

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high low volt cut off with delay alarm circuit ppt for pdf

Abstract

This straight forward circuit will protect electrical appliances from over voltage as well as under voltage. The circuit also produces an alarm when the power supply comes back. An ideal circuit for home to protect your valuable equipments from voltage fluctuations. The same circuit with some modifications can be used to make a automatic voltage stabilizer.

When the mains voltage is in the normal level, the voltage at the negative terminal of zener diode D4 will be less tha ....etc

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This power failure alarm project is a power supply monitoring device that will trigger a buzzer when the mains supply cuts off. At the same time, the light emitting diode will be turned ON. This device is helpful to inform the loss of power supply to some critical installation such as a pump in a fish tank. Once the buzzer sound, you will know that there is a loss of power supply and actions need to be taken to rectify the situation by providing alternative power supply or relocating the installation. ....etc

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A panic alarm is an electronic device designed to assist in alerting somebody in emergency situations where a threat to persons or property exists.

A panic alarm is frequently but not always controlled by a concealed panic alarm button. These buttons can be connected to a monitoring center or locally via a silent alarm or an audible bell/siren. The alarm can be used to request emergency assistance from local security, police or emergency services. Some systems can also activate closed-circuit television to record or assess the event.

M ....etc

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