PCI 6221 electric pulse

[cobbe]

Is PCI-6221 apropriate to generate 1 ms - 0,1 ms electric pulse with defined width and controlled height of pulse? If not, which antoher card is suitable for this use.

I am analphabet about this topic.

Thank You

[Aaron_W.]

It can depending on the rise time / fall time you need for the pulse and other factors. What amplitude range do you need to generate? 0-10V? How fast or often do you need to generate these pulses? How much current does it need to supply? More details on the application would be helpful.

[cobbe]

Thank you for reply. I need to measure electro-optics properties of PZT. I need to generate pulse for organization elctric dipoles. I need one pulse in several minutes (one pulse for one measuring process). Amplitude range should be 0-60 V. Now I have no more details.

I have unitilized this card, so I find out if may I use it. Or what else card should I buy.

[Aaron_W.]

There are specifications for every card NI makes, this is always a good place to start when looking for details on NI hardware. The 622X Specifications will give you more info on your card. However you will notice that your card can't do 60V (can only do +/- 10V) and it can only supply 5mA max.

60V is higher than you are going to be able to do with standard DAQ cards. You need to look at something like a Source Measurement Unit (SMU) or a Power Supply. You will also need to have a sampling rate of at least 10kS/s to achieve your 0.1 mS pulse. Look at the PXIe-4138, it supplies up to 60V and has an output rate of 100 kS/s. This solution will also require that you purchase a PXIe Chassis and PXIe Controller (MXI or Embedded). 

If you are very unfamiliar with the NI Hardware I would recommend reaching out to your local NI resource. You can find them by going to ni.com/contact and searching for a local Office or Local Sales Engineer.

[cobbe]

Hallo,

thank you for your answer.

I have contacted my collegue, to be more specific with requerment we need.

In final, we need to get electric pulse on demand. The resulting pulse should have height 20-100V, with duration 1ms-0.01ms. As you have mentioned, the PCI-6221 output is limited to be 10V. It is clear, we have to add an home-build electronic unit which will provide us voltage amplification (such as voltage multiplicator).

With my collegue we were thinking about following possibilities. Please, what is yur opinion which one is simpler or more feasible.

1) just to use analog output (0-10V), which we then multiply (amplify) by factor 10. Specification says, that maximum update rate is 833 kS/s per one channel. Please, does it mean that we can have a single pulse of width about 1.2 us? I mean, if we ask card to provide 0V,0V,than just once e.g. 5V, and again zero V, can we create sharp pulse by this way? I mean, can we make relatively quick pulses by this way?

2) second idea I was thinking was to separate pulse duration generation (done by digital output), and pulse height (done by analog output). Then, the final pulse would be build by aditional electrionics (voltage amplificator and quick transistor controlled by pulse).

Please, can I program digital output, to generate rectagular pulse on-demand of a given length (let's say down to 0.01ms) by digital output? Do you think better way is to use PFI (programmable function input), or just ordinary digital output?

We dont have a strict specification for rise/fall time, just want to have them 'as good as possible'.

Thank you for any help.

[Aaron_W.]

With the options you are looking at here is what I think.(side note: I'm not an expert at Analog design)

1) Yes, when you have an update rate at 833 kS/s that basically means that you pass an array of points to the card and have it generate those points. So, if you had an array of 0,0,5,0 and had it update at a rate of 1kS/s then you would see a 5V pulse that was a duration of 1 ms long. Now, depending on how other properties are setup DAQmx can "loop" this waveform or play it out only once. If you build a good amplification circuit then I don't see a problem with this. Just keep in mind you can't source more than 5mA with your AI channel.

2) This seems like adding complexity when you don't need to, it basically seems to me that you are taking the solution for #1 and instead of having a waveform generated you are going to leave the Analog Output on continuously and then use a digital line to switch the signal on or off (assuming you are using a relay or something similar). You can generate out a digital waveform with the PCI-6221, but a hardware timed waveform can only be generated with Port 0. The PCI-6221 is from the M-Series family of cards and it doesn't have it's own digital timebase to generate waveforms, so you must use another timebase from the PCI card to help generate a digital waveform. This could be the Analog Input, Analog Output or Counter timebase. It's not over complicated to do, there are examples. Ports 1 and 2 (also labeled as PFI lines) are not capable of hardware timed digital input / output. For your update rates of 1 ms - 0.01 ms you will need hardware timed waveforms.

If it was me, I would just try amplifying my AO waveform and see where that gets me. Keep in mind of the current draw from your AO channel as you don't want to damage the card and make sure that whatever circuit you design has a frequency response fast enough to allow a pulse of 1ms - 0.01 ms.

[Henrik_Volkers]

PZT Plumbum Zirconate Titanate ?

slew rate?

capacity of the PZT?

From a physical view: a defined voltage, current or charge?

assuming a 100nF PZT

100µs pulse length isn't that fast but charging a 100nF PZT actor  to 100V in 1µs

Q=C*U=100nF*100V=I*1e-6=1e-5FV ->    you will need 10A for 1µs or slowly charge a  C_load of 100nF  to 200V  , now switch C_load to your PZT and after 100µs(or pulse length) apply a shortcut  .  The question is how fast can you switch a low RS_on FET 😉 they need high currents too, but driver for this common task exists.