Arduino AC rotational speed measurement

[cola1988]

Hey

i need your help.

get the RPM of my DIY DYNO into Labview. What i already did and have:

• Inductive Sensor with perforatet Disk
• Recitified 0 - 15V AC to 1-4V DC with a  bridge rectifier (Arduino needs DC)
• --> Works, measurable with multimeter up to 1500 RPM (Stable voltage which follows the RPM)

Problem:

I only get a really noisy signal when i read the analog value (It works fine when i put a 1.5 Volt battery on --> constant value) but the RPM signal is so noisy and goes up to 5 Volt (My multimeter says only 3 Volts -.-).

i testet a program with "analog read" and "continues sample".. (picture)

When i rectify a voltage of 15 V ac from a transformer the measurement is no problem with arduino/labview (picture)...

What i thought about:

As an Example 600 RPM

My perforatet Disk has 29 teth.. so 600 RPM = 10 1/s  --> 10*29 teth = 290 signals per second --> Can i measure this with such a precission?

Do you have some solution or input? i don't really know what to do....

Best regards Phil

[Kristoff2]

Hey Phil,

What sort of DMM did you use to measure the output?  Most bench top DMMS have a pretty slow update rate, so it's possible you were missing the 'noise' that the Arduino is able to detect due to it's faster sample rate.

Do you have an oscilloscope you can use to test the output from the Dyno?  Can you also give us some more info on how the dyno works (parts used, circuit schematic, etc).

Thanks!

-Sam K

LabVIEW Hacker

Join / Follow the LabVIEW Hacker Group on google+

[cola1988]

Hey Sam,

thanks for the reply!

I'm using Labviiw 2009. I don't find the DMM on the function explorer. So i don't think i usw it... At the moment i download the NI-DMM from NI. Hope it works.

Next week i'll try with a oscilloscope from my university.

I think the problem is the Interface. I'm really new in this materia because i'm a mechanical engineering student .

So i'll try: My perforatet Disk has 29 teth.. so 600 RPM = 10 1/s  --> 10*29 teth = 290 signals per second ; but i have highs and lows. So 290 *2 = 580 Signals per Second to get all signals.

Means i have to transfer 580 bits to Labview --> is that correct? (i mean only the data)

With a Baudrate of 115000 bit/sec this could not be the Problem from Arduino.

Regards Phil

[emreoztoklu]

hey cola1988 , can you put here your document. because, ıt is difficult to look on picture... also, ı am ınterested as a same project.. have a nice working..