Michael A. Terrell wrote:
"
Durable-AC-80-260V-LCD-Digital-20A-Volt-Watt-Power-Meter-Ammeter-Voltmeter
US $7.99 plus shipping."
That's pretty slick for ten bucks, for common AC monitoring.
Unfortunately, the specs don't say if any measurements are true RMS or not. For the voltage, average reading is sort of OK since the line will be "mostly" sinusoidal, but current may be some nasty waveforms, and so will the power that goes with it, so true RMS is best for accuracy. There are ICs that can make the V and I measurements with ADCs, and properly calculate these and other AC parameters. If they've used such a one, it could be a very cool little monitor - especially for the price.
If anyone is planning to get some to try out, please let us know what you find, and if they are capable of "true" measurements - it's easy to figure out with a few experiments. If these are indeed capable, then I'd be interested in getting some too.
Ed
