Thanks for your answer Andrew, I'm going to checkt the ADE7763. In fact I was studying now the MCP3909 or MCP3901. These products look similar to the ADE7763. Any advice to choose the best one to interface with BB is very welcome.
Regards. José L. El jueves, 31 de octubre de 2013 19:35:50 UTC+1, AndrewTaneGlen escribió: > > Hey Jose, > > You could implement a very basic rectifier > http://en.wikipedia.org/wiki/Rectifier#Single-phase_rectifiers to get an > always-positive voltage > > Alternatively, you could use something like the ADE7763 ( > http://www.analog.com/en/analog-to-digital-converters/energy-measurement/ade7763/products/product.html), > > in combination with your step-down transformers to get all of the > volts/amps/power/phase infor you're after. I would recommend this option. > > Regards, > Andrew. > > On Friday, 1 November 2013 05:40:47 UTC+13, José Luis Redrejo wrote: >> >> >> >> El jueves, 31 de octubre de 2013 13:28:12 UTC+1, Dieter Wirz escribió: >>> >>> Really ouch. I you do it like this and connect your BB(B) to the lan, >>> then all computers in your school are under tension (Brrrzzzz)! >>> Therefore: NEVER USE A VOLTAGE DIVIDER WITH NET CURRENT, unless you >>> really now what you do! >>> You need to have a galvanic separation like a transformer or a diode. >>> >>> >> I do, I do, maybe I didn't explain it . In my first message, the CONN_2 >> connector is connected to a 220/9 AC Transformer, so, I'm using 9 V AC to >> feed that circuit. >> >> >> >>> Have a look at this: >>> >>> http://www.instructables.com/id/Real-time-Web-Based-Household-Power-Usage-Monitor/?ALLSTEPS >>> >>> >>> >>> >> Great, it's very similar to what I want to do. But, re-reading the >> article I see he's using a power factor of 0.75 and a voltage value of 110 >> V, to calculate Active Power. I want to measure these parameters to get the >> real active /reactive power values, that's why I have the ADC_VAC line in >> my circuit. That's exactly the line I don't know how to pass from >> negative/positive values to only positive values lower than 1.8 v to feed >> the BB ADC. >> >> >> >> >>> >>> On Wed, Oct 30, 2013 at 10:31 PM, Przemek Klosowski >>> <przemek....@gmail.com> wrote: >>> > Ouch, and another ouch since you seem to live in a 220VAC country. You >>> can't >>> > just connect 220V to a voltage regulator---it has maximum allowed >>> input >>> > voltage around 35V---you'd exceed that by a factor of almost 10. >>> > >>> > You probably should either do some reading about line voltage >>> electronics >>> > and 220V power supplies (hint---what you propose could work if you >>> used a >>> > transformer to get 220V down to 12V or so). >>> > >>> > My suggestion to you would be to consider a low-cost commercial power >>> meter >>> > like Kill-A-Watt ($20 or so) then point a BBB with a webcam at its >>> display, >>> > and do >>> > a little image processing to read out the power. People also cracked >>> them >>> > open and interfaced directly to their internal circuitry. >>> > >>> > >>> > On Wed, Oct 30, 2013 at 2:57 PM, <jred...@gmail.com> wrote: >>> >> >>> >> I'd like to use my BeagleBone Black to build a small power efficiency >>> >> station for my school. For that I plan to measure power consumption >>> using a >>> >> current transformer and a voltage transformer, feed the data into a >>> small & >>> >> fast database and show it through a web interface to the school >>> staff. >>> >> I see that 50 Hz are not a problem for BB ADCs, but I'm not sure at >>> all >>> >> using them is a good idea. >>> >> Intially I planned to use the same voltage I must measure to power >>> the BB. >>> >> I'm starting from a circuit like the attached one (replacing the >>> UA78M33 by >>> >> a UA7805CKCT which provides up to 1.5 A output) >>> >> >>> >> Changing the R1/R2 divisor I can make the 220V signal lower , but I'd >>> >> always get a signal with a negative side (-0.9V - +0.9V) in the best >>> case. >>> >> Same for the current transformer, after applying its output to a 100 >>> ohms >>> >> resistor. So, first, is it an awful idea to use BB for this purpose? >>> If not, >>> >> how can I avoid the negative part of the signal before feeding the BB >>> ADCs? >>> >> >>> >> Thanks in advance >>> >> >>> >> -- >>> >> For more options, visit http://beagleboard.org/discuss >>> >> --- >>> >> You received this message because you are subscribed to the Google >>> Groups >>> >> "BeagleBoard" group. >>> >> To unsubscribe from this group and stop receiving emails from it, >>> send an >>> >> email to beagleboard...@googlegroups.com. >>> >> For more options, visit https://groups.google.com/groups/opt_out. >>> > >>> > >>> > -- >>> > For more options, visit http://beagleboard.org/discuss >>> > --- >>> > You received this message because you are subscribed to the Google >>> Groups >>> > "BeagleBoard" group. >>> > To unsubscribe from this group and stop receiving emails from it, send >>> an >>> > email to beagleboard...@googlegroups.com. >>> > For more options, visit https://groups.google.com/groups/opt_out. >>> >> -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. 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