With designed fire alarm

Here is a switch alarm fire with LDR (according to strength light) as the light sensor. Warns the user of fire accidents. Inspired by the smoke of a fire. This smoke between a LED and passes an LDR, reduces the amount of light fell on the RDA. To increase the resistance of the RDA and tension for the high base transistor because then activated alarm which supplies designed, is concluded.

The thermistor offers a bit of resistance to high temperatures and high resistance to the phenomenon of low temperatur.Dieses here is used to detect fires.

(Designed) as a free current audio frequency oscillator is Ic1 configuré.Les transistors T1 and T2 IC1 IC1.Die (PIN 3) unit is based on the transistor output torque of T3 (SL100) that generate audio frequency values designed resistor R5 and R6 altavoz.Dependen readers and capacity C2.When thermistor is hot, there is a path of low resistance to the positive voltage based on the transistor Q1 diodes D1 and resistance R2.

CAPACITOR C1 fresh until positive and growing voltage is sur.Plus C1 set the alarm time more positive bias based transistor T1 applied (BC548) .the transistor T2 offers collectors at the base of the transistor T1 T2 is bound is a positive voltage to pin 4 (reset), the selected (designed) IC1 and s0 inactive .Resistor in absence of which stops D1 hält.Dioden positive voltage capacitor C1, if the thermistor in conjunction with the positive voltage cools designed landfill outside and provides the source before the transistor Q1 weighting inhibits Pfad.Es high resistance.