Posted by mdurki (vaughan@…>)
Any one know how to calibrate or check the reading of a volt meeter?
I have two and they differ by .15, which is not negligible.
Incidentally, the newer reads the higher. Neither comes close to that
built-in meter on the boat, but I have never thought that was reliable.
Posted by markmyatt (mark@…>)
— In freedomyachts2003@yahoogroups.com, “mdurki” <vaughan@…>
wrote:
Any one know how to calibrate or check the reading of a volt
meeter?I have two and they differ by .15, which is not negligible.
Incidentally, the newer reads the higher. Neither comes close to
that
built-in meter on the boat, but I have never thought that was
reliable.
That “.15” is I assume “.15” of a volt on a nominal 12V (not 15%).
If one tells the truth then, on a 12v system, the error is:
(.15 / 12) * 100 = 1.25%
Which is pretty good.
To see which is the most accurate you need a reference voltage. You
can build one with a zener diode, resistor, and battery … although
even expensive zener diodes have a precision (“tolerance” is the
jargon) of about ~1% anyway so you might never know. If you have a
full DC regulated power supply (PSU) then you could check the
voltage measured against the nominal PSU voltage under light load
but the problem with this is that not all regulated supplies are
well regulated and they are usually based around a zener diode and
have that ~1% tolerance anyway.
Another option is to find an electronics workshop or, better still,
a university laboratory as they might have a “precision
voltmeter” (which should be accurate to 0.1% or better). A lab will
also have a good reference voltage source that they use to calibrate
their instruments.
I think that 0.15V on a 12V supply is “negligible”. Most electronics
work on a 5% tolerance. Components with 1% tolerance are pretty
expensive.
I hope this helps,
Mark
Posted by Duncan Potter - Diacon (dpotter@…>)
If you are at a college or university (as your email address suggests) go
to the engineering department and check your meters against their precision
units. If that’s not an option, go to an electrical equipment distributor
(Grainger/Graybar, etc) and check your meter against the most expensive
Fluke meter they have in the case. Bring along a 9 V battery for your test
voltage. The Fluke will be accurate. Fluke makes the best general purpose
multimeters and they can be had for not too much money also.
Posted by svbagatelle (svbagatelle@…>)
The specs for the digital meter on my new Blue Sea panel say that it
is accurate to + or - .01 volt. I compare it to my handheld
multimeter and it does indeed match to the second decimal place.
Paul F30 “Bagatelle”
— In freedomyachts2003@yahoogroups.com, “markmyatt” <mark@…>
wrote:
— In freedomyachts2003@yahoogroups.com, “mdurki” <vaughan@>
wrote:Any one know how to calibrate or check the reading of a volt
meeter?I have two and they differ by .15, which is not negligible.
Incidentally, the newer reads the higher. Neither comes close to
that
built-in meter on the boat, but I have never thought that was
reliable.That “.15” is I assume “.15” of a volt on a nominal 12V (not 15%).
If one tells the truth then, on a 12v system, the error is:(.15 / 12) * 100 = 1.25%
Which is pretty good.
To see which is the most accurate you need a reference voltage. You
can build one with a zener diode, resistor, and battery …
although
even expensive zener diodes have a precision (“tolerance” is the
jargon) of about ~1% anyway so you might never know. If you have a
full DC regulated power supply (PSU) then you could check the
voltage measured against the nominal PSU voltage under light load
but the problem with this is that not all regulated supplies are
well regulated and they are usually based around a zener diode and
have that ~1% tolerance anyway.Another option is to find an electronics workshop or, better still,
a university laboratory as they might have a “precision
voltmeter” (which should be accurate to 0.1% or better). A lab will
also have a good reference voltage source that they use to
calibrate
their instruments.I think that 0.15V on a 12V supply is “negligible”. Most
electronics
work on a 5% tolerance. Components with 1% tolerance are pretty
expensive.I hope this helps,
Mark