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.
Have a look at this: http://www.instructables.com/id/Real-time-Web-Based-Household-Power-Usage-Monitor/?ALLSTEPS On Wed, Oct 30, 2013 at 10:31 PM, Przemek Klosowski <[email protected]> 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, <[email protected]> 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 [email protected]. >> 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 [email protected]. > 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 [email protected]. For more options, visit https://groups.google.com/groups/opt_out.
