Pico Technical Support and Discussion Forum

Clive Avery · Guest

We're attempting to use a picoscope to detect/log/measure voltage surges on control lines on a rail vehicle. Our problem is that the picoscope detecting the surges before it's connected to the wires! We suspect high EM fields in the area. I've noted several responses relating to earthing the laptop to which the the pico is connected, but can't see any obvious way of grounding the pico itself. Any hints? Incidentally is the case screened? I acknowledge that "RTFM" might be a valid response here but I've just had this dropped on me and I'm looking for a quick solution...

matthew · Posted: Fri Apr 25, 2003 8:42 am Post subject:

Hi Clive,

I just wanted to check that if you are using an ADC without isolation, you aren't using it for voltages above 42V dc (for safety reasons)?
The units are tested to standard EMC regulations so they will perform well under normal conditions. However ... they are not screened, so if you have particularly strong EM fields then you could pick up some noise.

Poor grounding would account for a noisy signal so this is the first thing to solve. This can be achieved by connecting the outer shell of the parallel port connector to a known ground point. Some ADCs don't ground the outer shell though ... if you have an ADC-10, 11, 12, 40 or 42 then ground pins 20, 21, 22 and 25.

Best Regards,

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