Quoting Hal Murray <[EMAIL PROTECTED]>, on Thu 17 Apr 2008 11:10:11 AM PDT:
> My power went out the other day. That reminded me that I've always been > slightly curious about that area. > > Are there any not-expensive boxes made for this? Or something that shows up > on eBay occasionally? Lots of dataloggers out there in the <$200 range. Check out things like the HOBO from Onset. you can also get embedded style computer from someone like Tern or Z-world or Vesta that has all the hardware needed, and comes with some basic software that you could use. > > > If I was doing it myself, I'd start with a low power (quiet) PC and a UPS. Battery and single board computer or data logger is much better... such an application doesn't need a video monitor, keyboard, etc. > Then I'd have a platform that could monitor other things too, like > temperature. > > Step 0 is just to measure when power is/isn't there. > I assume the UPS has a signal for that. > > Step 1 is to measure the voltage. > This takes an A/D. The standard PC audio input might be appropriate. no DC coupling on the audio card. Much better to either get something with the appropriate A/D OR a "one-wire" style interface. You could transformer down the 60 Hz, digitize as an audio signal, and process it appropriately. > I'd probably use an AC wall-wart transformer for isolation and a couple of > resistors to get down to a reasonable voltage. > > Step 2 is to catch dips and spikes. > That's just software behind the A/D. (assuming the A/D is fast enough) > > > As long as I'm dreaming... Suppose I wanted to measure the power my whole > house is drawing. What's available along the lines of a current transformer > on the main lines? My first thought is that nobody does that (for homes) so > it's probably horribly expensive. On the other hand there is a lot of > interest in energy conservation these days so it might only be somewhat > expensive. Lots of these available, in the few hundred dollar range.. http://www.powercostmonitor.com/p3982/power_cost_monitor.php http://www.theenergydetective.com/index.html you can also do something like watch the wheel goaround on the meter with a photocell or put a suitable current transformer ($5 surplus, $50 new) on the mains coming in. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.