An analog meter is actually showing you the current through the meter.
When you put the probes across a voltage source, the meter typically has
much higher impedance than whatever the voltage is feeding (the load).
At any rate, a volt meter generally has very high impedance, and it only
takes a few milliamps to achieve a "full" reading. Putting two in series
will double the impedance, and each meter should read half of whatever
voltage there is.
You don't want to put a SiteMonitor in series. You want to put it in
parallel.
bp
<part15sbs{at}gmail{dot}com>
On 4/8/2015 6:52 AM, Adam Moffett wrote:
Since I'm asking dumb questions:
Does having two volt meters in series significantly affect the
reading? V=IR implies that it should, because presumably the second
volt meter adds a little more resistance.
I have a battery charger with temperature compensation, so it comes
with a thermocouple that you put near the batteries. I thought it
would be convenient to wire a site monitor volt meter in series with
it so I could record whatever readings the battery charger is getting.
A shunt on AC will give you an AC voltage proportional to AC
current. If your monitoring device is OK with AC input then, yes,
you can do it that way. But if it is a sitemonitor, I don't think it
will like AC so much. And the output will have reference to the AC,
in other words it will be hot.
Normally you use a current transformer to measure AC. You can follow
up the current transformer with a diode bridge and cap or get one
that has a DC output.
This might work:
http://www.phidgets.com/products.php?product_id=3502
Not sure the range of the inputs but yes, if an input has a voltage
range that will cover your thermocouple it will indeed read it.
-----Original Message----- From: Adam Moffett
Sent: Tuesday, April 07, 2015 1:20 PM
To: [email protected]
Subject: [AFMUG] Dumb shunt question
This might be a dumb question:
Can I use a packetflux current shunt to measure current on AC, or are
they strictly for DC?
Ok, I have a second dumb question:
The shunt input on a Site Monitor II is just measuring microvolts
right? So if I'm not using it for a shunt, can I instead use that for a
thermocouple temperature probe?
