Comment summary #41
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Comment 401 ... 410
| date | article | author | comment |
| 04 maa 2015 00:19:01 | Arduino wattmeter | Freddy | You didn't mention if the 220 V is AC or DC. I assume it's a AC mains voltage. Be careful with this kind of voltages. You can easily hurt yourself or damage a computer connected to the Arduino. Read the safety section. The chapter "Voltage & current range" explains how the resistor R1 and R3 are calculated. If the voltage is 220 VAC, the top voltage is sqrt2 higher: 311 V. Because voltage are subject to fluctuations and voltage spikes can occur, It is recommendated to make the voltage range 400 V. The resistance R1 will be according to the equation 7.26 MΩ. A practical value is 8.2 MΩ. Assuming the current is a sinewave, the top value is 45 A. With a little room a 55 A will be suited. The resistor R3 will be according to the equation 0.001 Ω. |
| 03 maa 2015 12:02:16 | Arduino wattmeter | salim | hi, in this circuit the range is + or - 50, how the voltage divider will be if i am using 220v and 32 A. and also the resistor R3 ?? thanks |
| 03 maa 2015 02:16:48 | Arduino wattmeter | salim | hi, zishan, i am working on the same project and i think that instead of using rf transmitter use GSM module it is programmable with arduino. |
| 19 feb 2015 09:13:24 | Arduino wattmeter | zishan | Hi, i am working on a project and facing a problem that how an RF transmitter can be connected with digital energy mete to transmit power measured by the meter. please help and guide me.Thanks in advance |
| 18 feb 2015 12:50:17 | Accuracy, precision & resolution | Freddy | The terminology in the article is correct. Accuracy means how close your measured (averaged) values are compared with the true value. And precision is the spread of measured values around the average measured values. |
| 16 feb 2015 14:48:16 | Accuracy, precision & resolution | Guy Williams | In the Histogram section you are discussing the difference between Accuracy and Precision. Approx half way through Accuracy is specified and right at the end I was expecting Precision to be specified. However it appears Accuracy has been used where Precision should have been e.g. "This distribution of measurements is called accuracy.", or am I reading the section wrong? Cheers |
| 01 feb 2015 21:58:16 | Magnetic permeability | Freddy | If you measure the permeability of a powdered sample, you will measure a much lower permeability than a solid sample. This is because a powdered sample can be seen as a series circuit of the actually core material with air. Even a tiny dust particle between solid core halves has a huge effect on the measurement. |
| 01 feb 2015 21:49:13 | Arduino wattmeter | Freddy | The shunt voltage is now 55 mV, so a 75 mV shunt voltage makes not a huge difference. Only the amplification must be adjusted. This can be done to replacing R5 with a 6.8 kΩ (7.33 kΩ ideally) resistor. If the distance is not too long, an external shunt can be connected via a twisted pair cable, or better: a shielded twisted pair cable. |
| 01 feb 2015 18:55:08 | Arduino wattmeter | George in Albuquerque | Please add my compliments to the many accolades/have received for this project. And a question, please. I would like o measure much higher amperage, \\to 200 watts. Might the shunt be located separate from the remainder of thec circuit? I have in mind a 200v/200a 75mv shunt. If this is feasible, will the distance from the shunt to the circuit need to be considered? Thank you for sharing your ideas and work. And i wish you success with your new project. |
| 01 feb 2015 15:07:30 | Magnetic permeability | Asmat Elahi | Hello, can we measure permeability of a powdered sample by this method. if not , is there any other method for measurement of permeability of a powdered sample in a capillary tube. |