analog out amplification?

[Ujwal]

I understand that typically the Analog out voltage range is + or - 10V. I need some help regarding choosing a power amplifier ( if I need one).
Here's a brief discription of my application:
I have a electroactive actuator. I am trying to develop a VI which generates voltage levels specified by the user through a array. What I am trying to do is to generate a voltage spike, which is faster than the speed of response of my actuator. However, I am not exactly sure whether 10V would be sufficient amplitude for my spike. So I might need say upto 15V output. Since the DAQ cards have a maximum range of 10V, I suppose I will need a amplifier. So how should I go about in selecting a correct power amplifier or signal conditioner?
Here's what I have planned right now:

Labview VI---->DAQ card----->Analog out----->Actuator

I suppose for above stated reason, I should look for a power amplifier/signal conditioning between the analog out and my actuator.

Please help

[Ayman K]

Hello Ujwal,

You are Right. The DAQ card is limited to 10V output and if you require higher voltage levels you would have to externally amplify the output voltage. There should not be any restrictions to which amplifier to use since the output of your amplifier need not to be more than twice the maximum input coming from the DAQ card. There isn't a specific type of voltage amplifier that I have in mind but I know that the simplest amplifier out there would do the job. Good luck!

[Henrik_Volkers]

Ujwal,

have a look on your actuator and DAQ datasheet, I think you will need a amplifier for two reasons:
1. Output voltage , as you mentioned
2. Output current !! AO from DAQs I worked with have only a few mA output drive capability and I assume your actuator will need more power! Check it before(!) connecting your actuator to the your DAQ output, you might damage your DAQ.

Depending one your skills with electronics and your needs you can build your own amp. (It's mainly one IC and 2 resistors + power supply)

Basic data needed:
-Frequency range (DC? up to ?? HZ (you want spikes, that means high freq) however the max update rate of your DAQ might give the limit.
-Voltage and current (internal resistor) of your actuator (power spec for your amp)
-Linearity needs

If your frequency range doesn't include DC (say 20Hz to 20kHz) you might try a cheap audio amp 🙂

[Ujwal]

Thanks for your attention. I think this information will be quite helpful for tackling my problem
So, you mentioned that the E series or M series boards have only few mA current output. My actuator actually does not need much current. So what is exactly would be the current output capacity for E and M series boards corresponding to +/-10V voltage output range.
Thank you.

[Ayman K]

Hello Ujwal,

The output current drive is +/- 5 mA for E series and M series devices. M series devices have an overdrive current of 10mA (622x devices) 20mA(625x and 628x devices).

Ayman K

[Ujwal]

So, if I exceed the 5mA capacity and go to say 20mA for a 6259 M series board, will it damage my board??
Thank you

[Otis]

Hello Ujwal,

It sounds like you have an application where you know you will be sourcing larger amounts of current than the boards are really designed to output.

While the boards will not be damaged by using 20mA of current for shorter periods I would recommend that you try to create some sort of external current amplification circuitry if you know that the 5mA will not be enough current for your needs. You can do 20mA, that's why there is overcurrent circuitry, but if you need more current then try to make the proper circuitry to handle the extra load.

Regards,

[RVallieu]

It turns out I will need to do the very same thing.  I have a small linear actuator that operates at +/- 5VDC and 360 mA.

The system has a PCI-6722 card that I am using to trigger other devices so I would ideally like to use that.

[Otis]

Hi RVallieu,

If you need 360mA of current then you will definitely need some sort of external amplifier circuitry.

While I don't know of anything that can linearly amplify at up to 360mA of current, perhaps another user here on the forums could suggest a chip.

Regards,

[RVallieu]

I'm thinking a simple DC Transducer might work.  I'll already have several power supplies in the system near the actuator that the transducer could pull power from...hmm.