## RE: [Electronics_101] Re: old ammeter

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• I make my low resistance shunts out of thin steel wire although heating element wire can be used too. The trick is to accurately measure it. Rick ... From:
Message 1 of 51 , Feb 13, 2013
I make my low resistance shunts out of thin steel wire although heating
element wire can be used too. The trick is to accurately measure it.

Rick

-----Original Message-----
From: Electronics_101@yahoogroups.com
[mailto:Electronics_101@yahoogroups.com] On Behalf Of Kerim F
Sent: Wednesday, February 13, 2013 6:13 AM
To: Electronics_101@yahoogroups.com
Subject: [Electronics_101] Re: old ammeter

--- In Electronics_101@yahoogroups.com, "Nick" wrote:
>
> Hi guys, I'm fairly new to electronics and have a question about an old
ammeter that I acquired. I know that it requires a shunt as the wires on the
posts are small and it is a 100 amp meter. In the lower right corner of the
meter face it shows [E.S.=50mv ]. What can I use for a shunt and does it go
in series with the + or in parallel with the + and -. Will it read full
scale with the shunt installed [not that I would ever need that much]. Thank
you in advance for any info.
>

In parallel.
An ammeter is actually a sensitive voltmeter.
It seems the full scale voltage of your ammeter is 50mV.
If the the shunt is 1 Ohm, the full sacle current would be 50mA If the the
shunt is 0.1 Ohm, the full sacle current would be 500mA.
If the the shunt is 0.01 Ohm, the full sacle current would be 5A.
If the the shunt is ?? Ohm, the full sacle current would be 100A ;)

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Message 51 of 51 , Mar 21, 2013