The aim this project is to build a sensor that detects air flow using an incandescent lamp to detect the air flow. An LED will also be included in the circuit and as the air flow increase the brightness of this LED will also increase. A voltmeter will be connected in parallel to the Led to detect the changes in voltage as the airflow changes.Introduction:The circuit will use an incandescent lamp to detect the airflow. The glass around the bulb will have to be cracked, this will expose the filament.
The glass will be cracked by wrapping it round in masking tape and cracking, therefore the glass can be removed without damaging the filament. With the filament exposed to the air, a constant current source is used to slightly heat the filament. As it is heated, the resistance increases. As the air flows over the filament it is cooled down and therefore lowering the resistance.
An LED which is connected in the circuit detects these changes, as the resistance decreases the LED gets brighter. A voltmeter is connected in Parallel to measure the changes in voltage giving us estimation on the airflow. There will also be a potentiometer connected to the circuit; this will allow you to vary the sensitivity to resistance of the LED.Plan:The circuit will be supplied with 12volts. I will be using a board were you have to push the components into the holes, this will allow me to manipulate the circuit incase I have to change anything.To test the sensor and take down recoringsI will have to use a vacuum which blows out air.
I will test it from different lengths and after doing some preliminary tests I shall decide on the different lengths for my final results.Overall I expect the circuit to work well, as the sir flow increases the voltage across the LED will also increase, thus getting a straight graph in the analysis.Safety:There is nothing too dangerous as I am not planning to use the soldering ion apart from the 12v voltage which should not be in contact with the mouth, it could cause an electrical shock.The graph has a strong correlation and therefore agreeing with the predictions I had made earlier.
As the Airflow gets stronger, the LED gets brighter and thus the voltage increases across the LED. The sensor worked well as demonstrated in the graph and the results.With the line of best fit we can estimate the air flow of the vacuum at any distance. The equation of the line, worked out is y = -0.
0623x + 5.7487. With this equation we can also estimate the other value when given one value, for example we can estimate the air flow of the vacuum when given the distance from the sensor. The y value would represent the voltage, and the x value would represent the distance.Something else I noticed was t5he circuit was very sensitive to small changes in the airflow.
Evaluation:In conclusion, the sensor worked very well, and there were not too many problems. However when I was doing my testing, rather than using a vacuum and changing the distance, a device were you can control the actual wind speed would have given more accurate results.Over all I very happy with the way this project went. I did have to replace a few components as they got destroyed wile I doing my preliminary tests, but I had ordered spare. I got decent reading as the graph demonstrates.
