Agree with you re the LEM stuff, I've used them before & they are handy. Fo= r a one off, doing the rest is probably not worth the trouble if a ready ma= de solution exists for less than the time involved for design etc. It turns out that in this particular instance my problem may have 'gone awa= y' which is too bad given that I spent a couple of hours chasing solutions.= Still this is something that may crop up again, so I'd still be interested= in all people may have to say on the topic. Thanks, Joe -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of= Martin K Sent: 19 October 2012 13:06 To: Microcontroller discussion list - Public. Subject: Re: [EE]:MCP3905EV - MCP3905 Energy Meter Evaluation Board I believe that board accurately measures energy, real power * time. They are oriented toward metering applications (to charge money) and thus m= ay not be appropriate for general purpose applications. I don't believe tha= t board gives you current phase information. I would use a LEM current sensor module to measure the current: http://www.digikey.com/product-detail/en/HMS%2020-P/398-1061-1-ND/2628800 And an instrumentation amp. to measure the voltage across the load, using p= recision voltage divider resistors. This gives you a voltage proportional to current, and a voltage proportiona= l to voltage. Filter appropriately, and sample with an A/D converter. - Martin K On Fri, Oct 19, 2012 at 6:29 AM, Joe McCauley wrote: > Has anyone bought one of these? The user guide refers to a 250u Ohm shunt= .. Is that included? The photo in the website does not seem to show it, but = its not a great photo. > > I need to measure the power delivered to a motor from a phase angle power= module & did not want to reinvent the wheel, so this looked like it might = work. Its also a one off project, hence the reason I looked at an evaluatio= n board. > > Thanks for any pointers, or indeed any other options that might work inst= ead. > > Joe > > -- > http://www.piclist.com PIC/SX FAQ & list archive View/change your=20 > membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membershi= p options at http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .