DAQ card. Do I need signal conditioning on the front side?

[bob8907]

We are looking to use a DAQ card for a dynamometer project and many of the sensor inputs the the DAQ card will be analog. Mostly tach and temp and some inductive pickups from plug wires. Just curious when signal conditioning needs to be employed? Do we need the extra protection? Is that typical before a DAQ card?

Am I even posting in the right place??

 

[VEBill]

Assuming the Data Acquisition card front isn't already equipped with analog building blocks, then some of those signals are likely going to need conditioning before the A/D stage. But you have to look at each signal and compare it to the board's capabilities, one by one.

And I'd certainly be very cautious with the spark plug pick-ups. High voltage and expensive DAQ might all end in tears. You'll also need to think about timing resolution.

This is a good forum choice.

 

[bob8907]

Thanks for the reply. I do understand that the DAQ cards will usually have some analog inputs and I understand that each sensor will have to be carefully selected and compared to the cards ability. However, my partner was mentioning an additional conditioner before the card to protect it. I don't know. I seem to think that the card is made for it..

Regarding inductive picups. They are usually linear in response to the spark energy so with a 1000:1 unit, 12KV spark energy pulse would show up as 12V to the card. Obviously I will have to research that a bit to ensure operation is within card limits, etc. We likely would run MUCH less voltage than that.

 

[Skogsgurra]

With DAQ card, are you saying NI and LabView? They have lots and lots of information about all sorts of applications. Dig in there.

12 kV and dynamometer, sounds like you are doing an ICE job. Will you be measuring temperature in the cylinder? You may need to think about EMI getting into the system from the ignition.

Run differential mode. Single-ended will most likely conduct spark energy directly to the ground rail of your DAQ card and that can do many bad things to it. Wrong results, resetting the system, even destroy it if you are unlucky.

That may be what your partner has in mind.

Gunnar Englund

http://www.gke.org

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