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Generate double ended sinewave (+- X voltage value) using myRIO 1950

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Hope you are healthy and doing well,

 

Experience level: Novice

I generated a sine wave using myRIO 1950 (attached project) discussed in previous post.

 

Problem statement: myRIO 1950 generates sine wave from 0-5V and the device I am sending it to requires a sine wave of ± 2.5V. Also, I need to read an incoming sine wave signal of ± 2.5V. As it appears to me this cannot be achieved using myRIO1950 as it has single ended analog IO nodes (0-5V).

 

I did see that myRIO 1950 has ± voltage range for accelerometer, any possibility I can make it useful in my case?

 
 
 
 
 

Can someone please advice me on this. I cannot afford to change my hardware at this point.

Xonmyth743_1-1593608388875.png

 

Xonmyth743_0-1593608354146.png

 

 

 

 

 

 

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How much "electronics" do you know?  Suppose I gave you a voltage source that I said goes from 0 to 5 V, and also gave you a voltage source that was +2.5 V.  Could you build a circuit (maybe with an Op Amp powered by ±15 or ±5 V) that would take these two voltages and output ±2.5 V?

 

Similarly, to read a ±2.5 V signal with an A/D having a 0-5V range, you need to "add" 2.5 V to your input signal, transforming it to 0-5V (and, when you read the value, say "4 V", you can subtract 2.5 numerically to say "my input voltage must have been 1.5 V".  Assuming you know one end of a resistor from another, you should be able to build such a circuit.  Now, if only you had a source of 2.5 V ...

 

Bob Schor

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Thank you so much for your prompt reply. Your response sounds promising.

 

I do not know much of electronics, but I know someone who can help me build above mentioned circuit.

 

And just to make sure, there is no way I can get ± sine wave without making some modifications/additions to myRIO, correct? 

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@XM43 wrote:

And just to make sure, there is no way I can get ± sine wave without making some modifications/additions to myRIO, correct? 


Of course you can make modifications/additions to myRIO.  If you go on the Web, you can find plug-in boards that extend its capabilities.  You can also open the case, get out your soldering iron, and start playing around with its insides, but this will probably render it (to use a technical phrase) kaput ...

 

I don't know your ultimate needs, but you might also look at the multi-function USB-based NI devices, such as the NI USB-6002.  It has Analog circuitry (both input and output) capable of ±10 V swings, and can handle sampling rates (if memory serves) > 1 KHz.  It is also much simpler than the myRIO, which might be either a big Plus or a big Minus ...

 

Bob Schor

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A little Electronics 101 is in order here...

 

A capacitor will block DC but pass AC.

 

Therefore if you have a 5 volt sine wave with a 2.5 volt DC offset

 

Simply run that through a capacitor and it will remove the DC offset.

 

You will have your +/-2.5 volt sine wave centered on 0 volts.

 

 

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Capacitive coupling

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