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 Post subject: Re: Meter shunt value quesiion.
PostPosted: Dec Wed 06, 2017 8:33 pm 
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Joined: Mar Mon 17, 2008 5:05 am
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Location: Ashhurst, New Zealand
Be careful in using a switch to go between shunts for different ranges. If the switch is open when between ranges then......

Better to have the two shunts in series then a switch to short out the high current shunt leaving the low current shunt in circuit. I have used just a push button in the past.

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 Post subject: Re: Meter shunt value quesiion.
PostPosted: Dec Wed 06, 2017 9:13 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Maryland 20709, USA
TPAairman wrote:
With a 3 amp meter, the -0-1 amp section is not very big, meaning that the 100's of mA can be a very small section. So doing it this way, I have a higher resolution to my meter.

Compression of the low end of the AC current scale is normal.

That's why I used a spring-return toggle switch to drop the range to the meter's native 0.5 amps.

One resistor + a toggle switch is a heck of a lot cheaper than the added circuitry suggested.

In this situation, a 2.5A shunted range would make more sense than a 3A range.
With 2.5A FS, you just multiply each major scale division by 5 to get the true value.

- Leigh

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