Using a Arduino in place of a DAQ

Hello Alfred, you're new to Data Acquisition if you think the NI 6008 is expensive - it's only £183 and from NI  (not the cheapest source in the world). You might just get away with an Arduino instead but the NI box is 12 bit resolution and the Arduino's Atmel Mega processor on board ADC is only 10 bits.

What sort of turbine is it ?

You might be able to get away with less effort by connecting the piezo sensors to the PC's audio inputs and using audio software to look at the signals.

MK

Hi MK. Thank you for that. I have built a small jet turbine engine. The balancer is to balance the compressor, shaft and turbine wheel assembly.

I have built a balancer that works with 4 piezo sensors with ? an analogue circuit. It does not seem to work well. there is a circuit available that uses the USB-6008 DAQ.

I do however not want to spend so much money on the DAQ. The DAQ software does however give a very good image setup on the computer that would make balancing more accurate, as it indicates where the area of imbalance is. How would I be connecting the piezo sensors to the PC`s audio inputs?

Alfred

Hi MK. Thank you for that. I have built a small jet turbine engine. The balancer is to balance the compressor, shaft and turbine wheel assembly.

I have built a balancer that works with 4 piezo sensors with ? an analogue circuit. It does not seem to work well. there is a circuit available that uses the USB-6008 DAQ.

I do however not want to spend so much money on the DAQ. The DAQ software does however give a very good image setup on the computer that would make balancing more accurate, as it indicates where the area of imbalance is. How would I be connecting the piezo sensors to the PC`s audio inputs?

Alfred

What type of piezo sensor do you have, and what is the rpm at which you will balance. The PC will probably only have two audio inputs so it may not do for this. Why do you need 4 sensors, wheel balancers only use two, there are references on the web for doing it with 2 sensors.

MK

The balancer is constructed with 2 T-shaped structures with a piezo sensor (flat disc type) on arm. I got this from the Gas turbine association web.The shaft with its compressor and turbine wheel is put on top of this and rotated at not more than 5000rpm.The 4 piezos probably help in working out where the imbalance on the shaft and components are. This triggers a LED that shows a spot on the turbine. I know there are balancers with only 2 piezos, but they are constructed different. I can combine the 2 sensors on each T-structure if need be. At the moment I switch between the 4 sensors and view the signal on a analogue meter. The weaker the signal indicates that it is in balance. I am however finding it is not very sensitive as the 2 piezos of each T give different signal strengths. The original circuit I am using now was upgraded to a more digital version, but this uses the DAQ to connect to the computer. I am sorry I cannot be very technical with the electronics as this is not my strong point.

I do not know how to ad the circuit for you to view. This might make more sense to you.

Alfred

It would make a lot more sense with a circuit - if you can get the schematic up on screen you can press the print screen key to get it on the clipboard, paste it into paint, save as a jpg and include it on E14 using the little camera icon 'paste image' button.

If you are connecting piezo discs directly to a meter it won't work well.

MK

Hi. I am sorry I do not know how the clipboard works,

I have been able to attach them. Hope you can open the files.

Alfred

Attachments:

	main - schematic.pdf
	DAQ Connection.pdf
	sensor schematic.pdf
	Balancer mechanical.pdf

Although there are 4 piezo sensors they are wired up in such a way that there are only two channels of analogue data. Your problem is that the original designer of this system has out quite a lot of effort into it and I suspect has done a fair bit of work on the software. Although you could certainly use an Arduino in place of the NI DAQ you would need to modify the software quite significantly. Unless you are experienced in this sort of work it will take you a very long time.

Why not ask the original designer if they have any plans to port their code to an Arduino (or some other  very low cost hardware).

The only problem with using  a sound card with the sensors is that you really need a third input for the optical sensor.

I'm sorry but the only way round using the NI DAQ will require a lot of redesign work.

MK

Thanks a lot for going through all this for me. I probably would be better of getting the DAQ.

I shall shop around for a good price.

Alfred