Air flow detector circuit.
Description.
This circuit can give a visual indication of the rate of air flow.It can be also used to check whether there is air flow in a given space.
The filament of a incandescent bulb is the sensing part of the circuit.When there is no air flow the resistance of the filament will be low.When there is air flow the resistance drops , because the moving air will remove some of the heat generated in the filament.This variations in the resistance will produce variation of voltage across the filament.These variations will be picked up by the opamp (LM339) and the brightness of the LED at its output will be varied proportionally to the airflow.
Circuit diagram with Parts list.
Notes.
- The filament L1 can be made by removing the glass of a 40W incandescent bulb.
- The circuit can be powered from a 12 V DC power supply.
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Hi sir, I am student in University of pune, i am studying in B.E.(electronics) ,if you can give more information about the rest of the circuit, the function of each resistance, and the function of the capacitor, and if there any hints or notes, because iam trying to make a project semilar to this one. You can send them to me by an email.
and any modification pls suggest me Thank you.
and any project on temperature sensor .
where the air flow detector is used(list the applications)?
hello sir, its me again. I’m sorry if I asked to much but is it possibly for you to share with me the picture of the circuit?
Hi Min Tungsten has got a good Positive temperature coefficient (alpha) and will not get oxidized easily hence it is preferred.
Thanks, but one more question, I can just do it without the tungstan wire right??
Hi Min please refer to 26th Oct comment.
I am doing this circuit for my project but It doesn’t work. I really want to do this for my project. My only problem is the Filament, I still don’t know how to connect the filament to the board for testing. Please help me.
i’ll try that sir
thanks a lot for your prompt and positive replies!
Hi Shalini you can use it as it is but it will be bulky you carefully remove the filament including its end connecting stiff wire, and solder the filament through the stiff wire to a small pcb (a standard straight line one or a dotted one – veroboard). now your sensor is ready for use. infact you require a tungstan wire which has a good positive temperature coefficient, which is more suited for the project. since you do not get them freely in the market the simple above procedure is given. you can use a small radio bulb(as small as possible so that it can sense the temperature change big bulbs will take a loger time as they have inert gas filled in, 6 volt 300mA bulb) without breaking it.
Thanks a lot sir! But how do i connect the filament in the circuit. Pls help cause i’m pretty clueless about how to do it. After breaking the glass, how do I connect it in the circuit? Only the glass needs to be broken? not the other bulb attachments like the base also?
Hi Shalini you can use the 40watt bulb filament by carefully breaking the glass. this can be best done by keeping the bulb in a thick plastic cover and carefully giving a hit with a sharp tool. now carefully take out the filament and use it. the pot is for the flow level set adjustment. LED will come on when air flow sets in. to ckeck the operation first without any air flow adjust the pot such that the LED just goes off. now slowly bolw air on the filament the LED will come on, indicating the circuit is functioning.
Sir, also how do I use the filament specified in the given circuit? It’ll work properly no? I’m relying on it for my project. So awaiting a positive reply…
Sir, what is the purpose of the var. resistor (100k – R4)? what resistance do we have to set it to while monitoring the air flow? Pls reply asap… doing a project that needs to be submitted in the next 4 days
Its a nice work am also doing a project work on the air flow detector. pls if you can send its design to me thanks.
Sir, please i may also need its application and significance thanks.
Hi, Its a nice work. am also doing a project work on air flow detector. Please if you could help me with its design.
sir,can u tell, what improvement we done in air flow detector
any addition can we done???
please do explain the working of each component in air flow detector ckt…the connection is simple n works really good….please send the information to my mail….
actually i want to make air flow detector as my minor project so can u plz provide me PCB arrangement for this;;
also explain in detail about application in boiler furnace
can u list any other industrial applications of the circuit……..we are asked to give industrial applications
sir can explain in detail about application of air flow detector in boilerfurnace…………
can u list any other industrial applications of the circuit……..we are asked to give industrial applications
Thanks a lot for ur response….
i got output for the circuit ………but filament is very sensitive it is easily getting damaged…….can u suggest any other component in the place of filament ……
You can send them to me by an email.
Thank you
hi sir
The project seems to be quite interesting and I would surely try this project this semester.Could you please explain me the project in a bit more details.
If you can give more information about all the componantst, the function of each resistance, and the function of the capacitor, and if there any hints or notes,& how it works with datasheets.
I am student in knust, iam studying biomedical engineering,if you can give more information about the rest of the circuit, the function of each resistance, and the function of the capacitor, and if there any hints or notes, because iam trying to make a project semilar to this one. You can send them to me by an email.
Thank you
hi sir..
may you pls help us upgade ths circuit by putting different levels of required air flow
Any low noise operational amplifier will do to give the required gain and off set. 725, 308, 071, 3140 etc. the output of this ic can be fed to a 3 1/2 digital display normally comes with 0 to 200mV DC FS.
can i please know which ic an i use to get the analog out put from the filament to be converted to a binary digital output or directly to 7 seg display.
Hi SHIRISHA practical application in boiler furnace air flow measurement, will enable total combustion of oil, coal or gas. air flow measurement through any air duct. for temperature and pressure measurement you have to add suitable sensors like RTD pressure transducer etc.
to add digital indication you can use the analog value availabe at the filament through amplification, can be calibrated to velocity of air flow by comparison
Thanks for ur response sir …….
can u give practical applications of this circuit in industries………..
i also want to extend this project….like i want to include numerical indication of air flow level….
can include any other circuit to detect temperature or pressure in this can you send me circut
Hi Shirisha please go through my march12th comment, that will give you the idea on the principle of operation. air flow meters are of different type. measurement with rotating vane speed is anemometer, and hot filament type is the above one. both are fairly accurate if properly calibrated.
i also want to extend this project….like i want to include numerical indication of air flow level….
can include any other circuit to detect temperature or pressure in this can you send me circut
sir can i also know about application of this projec in industry ….more over how this instrument is different form other air flow detectors….i also need advantages,disadvantages and precaution to be taken…
dont mind please answer to my questions
hello sir i am shirisha from gnits……i am doing mini project on air flow detector …….i need complete information about working of this circuit and funtioning of each componenent placed ……
Hi Rupak the standard method is to use a rotating blade anemometer. this uses the principle of cooling due to air flow on a heated wire. as the air flow increases the cooling is greater. as it is a matalic wire with positive resistance temperature coefficient the value of resistance of the filament (sensor) is measured to indicate the flow.
sir,
the project seems to be quite interesting and I would surely try this project this year.Could you please explain me the project in a bit more details
thanx for giving the information of this project…
Sir…!
we are doing a project on air-flow detector…and we need to demonstrate and give the presentation to our Externals in the University…
so pls provide me the complete informations about the project with diagram & the picture of this project Air Flow Detector…!
Thanx…
Hi Ireti The IC 7805 forms a 60mA constant current source feeding the filament. The voltage drop across it is compared by the comparator IC and the ouput is produced. Normally cold bulb filament resistance is low(a positive temperature coefficient material) as it gets heated up the drop across the filament increases due to which the LED goes on. when the filament senses air flow the heat is removed hence the resistance falls down, due to which the LED goes off. If you want the operation other way, air more than a particular flow to indicate by LED going on, interchange comparator ICs inv and non inv port (4 & 5)
Hi sir, I am student in oou ago iwoye ogun state Nigeria, i am studying physics with electronics ,if you can give more information about this air flow detector circuit, the function of each resistance, and the function of the capacitor, and if there any hints or notes, because am to make a project on it. You can send them to me by an email.
Thank you
what is the need of IC7805 in this circuit?
sir i want to know whether this circuit can also indicate the direction in which air flows?
hi sir thanks to all give for information
What is the output voltage of this circuit?
Hallo Usama and Manish IC1 is a constant current source of 60mA for the filament. IC2 is a comparator. With the present circuit the LED will become dim with higher air flow. To make it brighter with higher air flow interchange inv and non-inv inputs of IC2. or alternately return the LED to ground instead of plus 12Volt. IC2 can be replaced with TL071. Happy assembling and enjoy
This is a simple but useful circuit, thanks for making it freely available. That said I expected the circuit to function in reverse, instead of the LED dimming when airflow is detected I assumed it would brighten. Any suggestions on how to modify the circuit so that the LED brightens with air movement? I tried reversing the input signal to the comparator and it does work but the output barely lights the LED.
i want the simple diagram of this circuit will you give mee plzz??
hello, give me some more information about this project
I think this wind meter circuit http://www.circuitstoday.com/wind-meter is better for a project.
pls sir/madam….!!
we are doin a project on air-flow detector!!
and we need to give a good presentation to our teachers….!!
so pls provide me with the informations about the project!!
pls sir/madam….!!
we are doin a project on air-flow detector!!
and we need to give a good presentation to our teachers….!!
so pls provide me with the informations about the project!!
it is good for air flow sensor and i says thanks more on your advice
project for air flow detector &the fuction of each components & how it works with datasheets
Hi sir, I am student in Cape Breton University, iam studying electronics and control systems,if you can give more information about the rest of the circuit, the function of each resistance, and the function of the capacitor, and if there any hints or notes, because iam trying to make a project semilar to this one. You can send them to me by an email.
Thank you
inclusion of track lay-out will b greatly appreciated by students aspecially. those who take electronics as a hobby