Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [meter]

125 questions
35
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2 answers

Why this small cut in Ampere meter shunt?

I have seen lot of ampere meter shunt like this. What is the reason for this small cut?
user_fs10
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27
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What do the line-and-circle symbols mean on these electric meters?

I was looking at an electrical installation and came across unfamiliar symbols on the front of a pair of meters. These are from three-phase 240v meters running on a timed system. One each for peak/off-peak usage. On the first image, I recognise part…
Ben
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Why is this meter giving different readings depending on its orientation?

My newly-restored (re-capped) 1950s vacuum tube voltmeter is now operational...but there's one further issue. The meter gives correct readings when lying on its back, but when oriented vertically- as I'd like to use it - the readings are wrong and I…
Simon Owen
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10
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3 answers

In below picture, is ammeter AC or DC? Is there direction for connection with load in series? If so what if I connect in wrong direction?

This is front view of analog ammeter. There are 2 terminals with nut and bolt behind it but nothing marked neither plus nor minus.
user2681304
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8
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Restoring and operating a temperature gauge from the Soviet space shuttle Buran

After the Soviet Buran (БУРАН) program was suspended in the late 1980s, the Buran space shuttle was housed in a hangar at Baikonur. That hanger unfortunately collapsed due to structural failure in 2002, destroying the spacecraft. A clear-out of the…
Polynomial
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8
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Why is a clamp meter unaffected by nearby wires?

I understand a clamp meter works by measuring the magnetic field generated by current flowing through a wire. It's well known that clamping 2 wires carrying the same current in opposite directions will show a null reading because one magnetic field…
Zmaster
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4
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Why doesn't commercial LCR meters' band start from very low frequencies?

I'm wondering why I can't find an LCR meter with frequency band that starts for example from 1 Hz. Is there some specific reason? EDIT: My question comes from the need to measure the impedance of a generic "component". I create a meter with an wave…
thoraz
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4
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3 answers

Building a pH meter circuit - is it feasible?

Let's say I have a budget of $15-20 to build a pH meter. I will then read the analog values from a microcontroller or such, but I want to first focus on somehow getting a reliable pH value on a shoestring budget. First of all, is this even possible…
T.K.
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3
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3 answers

How to light an LED when a voltage hits a certain point

Lets say I need an LED to indicate when a DC voltage reaches 5 volts or more. I don't want the LED to be dim when it is at 4.5 or anything. I just want it to be full bright at 5, 0 bright at anything below 5. Is there a way I can do this with…
skyler
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3
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Clamp meter readings

I have a Uni-t UT210e clamp meter. I noticed that when measuring AC current, the reading varies if I move the wire inside the clamp. The measured value displayed on the meter is higher when the wire is closer to the upper part of the clamp, and it…
beard999
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3
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Home-made impedance meter: what's the difference between voltage divider and active filter methods

I'm dealing with the measurement of impedance sweeping the frequency from 0,1Hz to 100KHz. On the web I found many methods but the most quoted seems to be the one which uses an operation amplifier in inverting low-pass filter configuration: Z…
thoraz
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3 answers

Using step-up converter in metering instrument?

I am designing a pressure calibrator (my first Real project), which is supposed to measure from 0-200.00 mmWC (20000 counts) using Silabs C8051F350 (inbuilt 24-bit Sigma delta ADC). Sensor used is a typical Wheatstone bridge type Differential…
Sajid
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3
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How can I extend the ammeter wires to my shunt?

Is it possible for me to locate my ammeter and shunt a few meters away from each other (more than intended by original wiring)? The extra wiring obviously has a resistance and provokes a false reading, which I have tested and found to be true. Is…
user45878
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Is there any such thing as a linear panel meter?

I like to use regular panel meters for showing data. I would like to know if there's such a thing as a linear meter, say 10 cm long or so. By linear I mean that the indicator moves up some scale in a linear fashion - like a bar graph, or something…
John
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Can I connect ten RS485 modbus kWh meters to one RJ45 modbus server?

If I have a fusebox with about ten/fifteen eastron sdm630 and Orno OR-WE-515 kWh meters with RS485 modbus, can I daisy chain them all to one Waveshare RJ45 modbus server? I'm new with this, but this is called a fieldbus, right? The end goal is to…
Tim
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