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recommendation for psu, multi-ch monitoring?

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recommendation for psu, multi-ch monitoring?

Postby sirdowny » Tue Apr 25, 2006 6:29 pm

Hi. I've looked over your product range and I have a few questions.

I'm looking for a system of data loggers/oscilloscopes to monitor & log voltages over a long (up to 24 hours) test period. I'm looking to test atx-spec power supplies (found in typical computers) which have 6 output voltage rails ranging from 3.3V to 12V. I need to be able to log 6 channels simultaneously.

If I understand correctly, the sampling rate is one of my determining factors. I don't need a super high sampling rate, as I'm primarily looking for trends, but I do want to be able to detect random spikes and examine the voltage ripples.

I was thinking of buying 3 PicoScope 2202 units (USB & each dual channel) and using the included software and excel macro to log 6 channels simultaneously. Again, I dont think I really need any high-speed units as this setup is to be used simple periodic voltage logging over a long time. Will the software allow me to monitor 3 2202 units simultaneously and is this setup the best choice?

what do you think?

Thanks a lot!!
sirdowny
 

Postby ricardo » Fri Apr 28, 2006 8:30 am

Hi sirdowny,

Thank you for your enquiry. Using 3 2202 units with PicoLog for logging over a long time is not a problem. The only thing though is that you will not get high sampling rates, the maximum sampling rate with PicoLog is 1 sample per millisecond. This is probably not fast enough to capture glitches.

If you are looking for a scope just for this application then you can use an ADC-11 instead of the 3 2202's. The ADC-11 has 11 input channels and the maximum sampling rate is irrelevant as you will be restricted by PicoLog to 1 sample per millisecond. The input range of the ADC-11 is 0 to 2.5V but you can use shunt resistors on the terminal block to bring the voltages down to the input range.

http://www.picotech.com/data-acquisition.html

The 2202's (and all our other scopes) can only sample at high speeds using PicoScope (oscilloscope software), which you cannot use for sampling over a long period of time.

Please let me know if you have any further questions or if you wish to place an order.

Best regards,

Ric
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Postby sirdowny » Sat Apr 29, 2006 6:31 am

Thanks for the response Ric. So if I understand correctly, I can use 3 2202s together, but only with the Picolog software and not the Picoscope software. Also I'll be constrained to a max sampling rate of 1 sample/mS.

I dont think the ADC-11/12 will work for me as I really need the exact measured voltage values (which all exceed 2.5V). Of course, I suppose if the voltage values (measured at the ADC-11/12) are just a constant ratio of true output scaled down by the shunt resistors, it won't matter huh? Would you recommend this setup over the 3 2202s?

Now I'm particuliarly interested in your software's ability to output (directly?) to excel. I'll be able to output the measured voltages of all 6 channels simultaneously to an excel file using Picolog for long periods of time (say up to 15 hours)?

Is this situation feasible?
sirdowny
 

Postby ricardo » Sat Apr 29, 2006 9:37 am

Thanks for the response Ric. So if I understand correctly, I can use 3 2202s together, but only with the Picolog software and not the Picoscope software. Also I'll be constrained to a max sampling rate of 1 sample/mS.


Thats correct. With PicoScope software you cannot use multiple units simultaneously, only one at a time.

I dont think the ADC-11/12 will work for me as I really need the exact measured voltage values (which all exceed 2.5V). Of course, I suppose if the voltage values (measured at the ADC-11/12) are just a constant ratio of true output scaled down by the shunt resistors, it won't matter huh? Would you recommend this setup over the 3 2202s?


3 2202's will cost you around £600 and the USB ADC-11/12 with the terminal block is only £160. I personaly would go with the ADC-11, it has 12bit resolution so it will give you very accurate readings. We can for a small charge modify the standard ADC-11 to increase its input range but I think only to +/-10V (I can check on Tuesday and let you know).

Now I'm particuliarly interested in your software's ability to output (directly?) to excel. I'll be able to output the measured voltages of all 6 channels simultaneously to an excel file using Picolog for long periods of time (say up to 15 hours)?


Yes, this is correct. You can use Dynamic Data Exchange (DDE) to transfer the current set of readings to Excel. I believe data will be updated once a second roughly.

Best regards,

Ric
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Postby sirdowny » Sat Apr 29, 2006 9:38 pm

We can for a small charge modify the standard ADC-11 to increase its input range but I think only to +/-10V (I can check on Tuesday and let you know).



That'd be great. Any chance you could bump it up to +/- 15V ? The extra charge isn't a concern.

Thanks again
sirdowny
 

Postby ricardo » Tue May 02, 2006 9:16 am

Hi Sirdowny,

I checked this morning and the most they can increase the input range is to +/-10V, I should also mention that in doing so the input impedance is reduced significantly.

I think the best option is to use a potential divider, if you choose sensible size resistors of high accuracy, you should get very accurate readings.

Best regards,

Ric
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