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amr mohamed
 
 


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Date of Birth : 1994-09-29
Join Date : 2010-11-12
Age : 22

PostSubject: Simple Fire alarm circuit   Mon 04 Apr 2011, 8:46 am


Simple Fire alarm circuit


Description of Service

Service warning fires using the simple provisional
555



Installation Service

This circuit is used as a thermistor TH1 thermistor sensitive to temperature. When increasing the temperature of the thermistor under
Resistance and vice versa so-called Thermistor with a negative temperature coefficient andshort NTC.
In the normal temperature of the Thermistor resistance is 10 kilo ohms and carrying a numberof
Ohms greater the degree of heat to the post-100 degrees Celsius.




Is connected to the provisional 555 in a multi-oscillator system is stable in the frequency range astable Audio
. Conversion Turanzsturin T1 and T2 is running the provisional 555 IC1.

Went up to the provisional transistor T3 thereby acting and leads to the generation of warning sound headset.

Oscillator frequency depends on the values ​​of resistance and the resistance R5 and R6 condenser C2.

To prevent and protect the thermistor is placed around the fusion of segments of the mica


cheers

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