JohnGaltLine posted:The basic thing with the isolation is that the circuit used in these meters will provide a short between the meter's ground and the measurement's "hot" side which will blow out the meter. Electricity will take the path of least resistance, which happens to be through the component used to measure the voltage, if it shares ground with the voltage being measured. At mains level voltages this happens in a beautiful show of smoke and flame, At lower voltage the components last a little longer, and might just last a while if the combined voltage of the input source and the voltage being measured is below the meter's rating, but most likely things will fail in fairly short order.
In the case above of powering from the 1033, it may or may not work, depending on the ac-dc converter you are using. if it is providing an isolated supply from the AC input, you're good.
I've also run into some discussion of using LM555s to create very basic switching supplies that will isolate the meter's supply from the measurement voltage. I'm unsure about this method just yet, but it seems like a workable solution, as long as the input voltage is high enough.
Links for more information:
Why non-isolated supplies blow things up.
Moving on, do any of you have the ability to test these meters with something that outputs a so-called "chopped" wave? Ex. the Zcontroller, or a CW-80, or ZW-C. I'm curious if they report a reasonably proper RMS reading, or if they get confused by such waveforms.
JGL
Thanks for the info & two links. I'm on board and hopefully won't smoke the meters.
Bob D
