This circuit uses an incandescent lamp to detect airflow (mendeteksi angin). With the filament exposed to air, a constant current source is used to slightly heat the filament. As it is heated, the resistance increases. As air flows over the filament it cools down, thus lowering it's resistance. A comparator is used to detect this difference and light an LED. With a few changes, the circuit can be connected to a meter or ADC to provide an estimation on the amount of air flow.
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| Rangkaian Pendeteksi Angin |
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LM339 Pinout |
The glass will have to be removed from L1 without breaking the filament. Wrap the glass in masking tape and it in a vise. Slowly crank down until the glass breaks, then remove the bulb and carefully peel back the tape. If the filament has broken, you will need another lamp.
List Component
R1 : 100 Ohm 1/4W Resistor
R2 : 470 Ohm 1/4W Resistor
R3 : 10k 1/4W Resistor
R4 : 100K 1/4W Resistor
R5 : 1K 1/4W Resistor
C1 : 47uF Electrolytic Capacitor
U1 : 78L05 Voltage Regulator
U2 : LM339 Op Amp
L1 : #47 Incandescent lamp with glass removed (See "Notes")
D1 : LED