7 replies to this topic

[labview1958]

I have designed an optical rpm circuit. Can it be improved? It is attached. How to show it in the forum.

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[M.Pathma]

I have designed an optical rpm circuit. Can it be improved? It is attached. How to show it in the forum.

"Optical RPM Circuit", all I can see is that you will get PULSE for each time the each time the light been reflected, the duration of the ON and OFF time is depend on the reflecting sticker size and your rotation speed, the faster speed, shorter duration, thus you DAQ need to measure the ON/OFF duration and calculate the speed.

If you have one STICKER then you will get ONE pulse each rotation, then you compute the time taken for ON-OFF-ON then you can estimate the RPM.

So, I think (in my humble opinion), this circuit should be called "Pulse Shaper"

Oh… yes… is your question about the circuit design OR the RPM measurement concept

[labview1958]

You are right. However is there any way the cct. can be made better. Maybe changing the resistor value, voltage etc.

[Imperator]

I have designed an optical rpm circuit. Can it be improved? It is attached. How to show it in the forum.

Hi Labview1958,



Guess this is the picture you may like to post...

You are able to upload the image to the forum by uploading and storing it in a web address, then right click on the stored image, click on Properties and copy the URL Path, and finally insert it as an image from the icon given in the Forum Message Board.

For this case, this is what I did:

1) I downloaded your file (which is in Word Format), click on the image, copied and paste the image to "Paint Program", and Save As "JPeg" on Windows Desktop.

2) Open "My Controls" found at the top of the forum page

3) On the left panel, click "Your Albums"

4) Goto "Select an Operation" and upload your image (remember to give a name to the Subject and Message Board e.g. both named as RPM Sensor), you can store many images in Your Albums.

5) You can also view your images, and you can right click your images, from Properties, you can copy the entire URL Path.

6) There is an "Insert Image" icon on the top of the Forum Message Board (where you write your forum messgaes), and paste the URL Path after clicking the "Insert Image" icon.

You're done... So hope that you can try it

Cheers...

[M.Pathma]

You are right. However is there any way the cct. can be made better. Maybe changing the resistor value, voltage etc.

Can you please advice the expected speed of your system, please indicate the ON-OFF-ON time chart, this is a very basic design, it will work under basic usage, but if you speed is higher then we need to think about the respond time and frequecy aspect of the design.

M.Pathma

[labview1958]

I am doing a study of between 100 to 3000 rpm.

[M.Pathma]

I am doing a study of between 100 to 3000 rpm.

Hi,

Please double check the following:

1) The comparator output is feed to DGND PIN 24 and the circuit ground is to 0-Gate Pin 48,, (I assume that the DAQ will be connected in-order)
2) The junction at the comparator output & resistor 1K is not joint (I assume you joint it and the 1K is pull-up)

For every time the "light is reflected" the you will get short-pulse (length depend on your sticker and speed), basically this circuit will work fine under the rpm you indicated.

If I where you, I will do away the comparator and use the RS-307913, 2K2 resistor (pull-up to collector to 5V) and then connect the Collector to DAQ input. Make sure the non-reflective section is BLACK.

The result will somewhere same with your comparator circuit.

M.Pathma

[labview1958]

Would the circuit work better if I connect and additional infrared source? More source more reflected infrared and better detection by the transistor? If so what type of infrared LED is suitable?