Feeds:
Posts
Comments

Posts Tagged ‘alarm’

Block diagram

 

 

Abstract

 

 

 

 

 

.

Read Full Post »

Block diagram

 

 

Abstract

 

 

 

 

 

.

Read Full Post »

Block diagram

 

 

Abstract

 

 

 

 

 

.

Read Full Post »

Block diagram

 

Abstract

 

 

 

 

 

.

Read Full Post »

Block diagram

 

 

Abstract

 

 

 

 

 

.

Read Full Post »

Abstract

This project is an ultra-sensitive fire sensor that exploits the direct piezoelectric property of an ordinary piezo element to detect fire. The lead zirconate titanate crystals in the piezo element have the property to deform and generate an electric potential when heated, thus converting the piezo element into a heat sensor. The circuit described here is very sensitive. It gives a warning alarm if the room temperature increases more than 10°C. The entire circuit has two sections—the sensor and the power supply section.

The front part of the circuit has a sensitive signal amplifier. It gives a high output when temperature near the piezo element increases. In normal condition, the sensitive signal amplifier gives a low output and the remaining circuitry is in a standby state.

If heat near the piezo persists, after one minute, and the buzzer starts beeping. If heat continues, after four minutes, the relay will be energized. The solenoid pump connected to the N/O (normally opened) contact of the relay starts spraying the fire-ceasing foam or water to the possible sites of fire.

Power supply section comprises a 0-18V, 1A step-down transformer with a standard full-wave rectifier formed by D1 through D4 and filter capacitor C1. A regulator is used to get fixed positive 12V. An optional battery backup can be provided if the mains supply is cut-off due to short-circuit and fire. A 12V, 4.5Ah rechargeable battery can be used for backup to give sufficient current to the solenoid pump.

block diagram

 

Abstract

 

 

 

 

.

 

Read Full Post »