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ELECTRONICS ELECTRONICS Frost Alarm Frost Alarm
ELECTRONICSELECTRONICS
Frost AlarmFrost Alarm
ELECTRONICSELECTRONICS
When the thermistor When the thermistor temp is high the temp is high the resistance is low resistance is low
and the transistor is and the transistor is off.off.
ELECTRONICSELECTRONICS
Frost AlarmFrost Alarm
ELECTRONICSELECTRONICS
When the thermistor When the thermistor temp is low , the temp is low , the resistance is high resistance is high and the transistor and the transistor switches on.switches on.
ELECTRONICSELECTRONICS
Fire AlarmFire Alarm
ELECTRONICSELECTRONICS
When the temp is hot the When the temp is hot the thermistor resistance is thermistor resistance is
low so it takes little low so it takes little voltage and so the resistor voltage and so the resistor takes most of the voltage takes most of the voltage
and so the transistor and so the transistor switches on. switches on.
ELECTRONICSELECTRONICS
Fire AlarmFire Alarm
ELECTRONICSELECTRONICS
When the temp is cold When the temp is cold the thermistor takes the thermistor takes
most voltage and so the most voltage and so the resistor takes little and resistor takes little and
the transistor is off.the transistor is off.
ELECTRONICSELECTRONICS
Burglar AlarmBurglar Alarm
ELECTRONICSELECTRONICS
When the L.D.R. is in the When the L.D.R. is in the light ,the resistance is light ,the resistance is
low so the voltage is low low so the voltage is low and the transistor is offand the transistor is off
ELECTRONICSELECTRONICS
Burglar AlarmBurglar Alarm
ELECTRONICSELECTRONICS
When the L.D.R. is in the When the L.D.R. is in the dark its resistance is high dark its resistance is high
and the transistor switches and the transistor switches on.on.
ELECTRONICSELECTRONICS
Time Delay CircuitTime Delay Circuit
ELECTRONICSELECTRONICS
When the capacitor When the capacitor charges up to a certain charges up to a certain voltage after a certain voltage after a certain time , the transistor time , the transistor
switches on.switches on.
ELECTRONICSELECTRONICS
ELECTRONICSELECTRONICS
There are 3 process There are 3 process devices,devices,
The NOT gateThe NOT gate
The AND gateThe AND gate
The OR gateThe OR gate
