Comment summary #29
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Comment 281 ... 290
| date | article | author | comment |
| 07 maa 2016 01:09:11 | Arduino wattmeter | Freddy | Also with a 9 volt battery and a Fluke 177 (Ri=10MΩ @ 100mVDC range). BAT85 (schottky) 1.95V! => 195nA 1N4148: 40mV => 4nA BF245B (JFET): <0.1mV => <100pA |
| 07 maa 2016 00:44:26 | Arduino wattmeter | Allan Lind | I have the same trouble with my Current reading not being zero with no current flow. I went through my diode drawer just now and found a couple of Diodes less than 20mV measured in series with a Fluke 77 and a 9V battery. These are glass diodes red inside with a green stripe on one end. There are two markings: 3M and 22Z. I think they are 22V Zeners. Forward volt drop is about 0.7V so that rules out schottky I guess. |
| 07 maa 2016 00:06:15 | Arduino wattmeter | Freddy | No, don't use Schottky diodes, it would make it worse. The leakage of a signal Schottky diode is 100 times higher. A JFET (BF545 for example) diode (D and S shorted) is much better choice. Or use a specially low leakage diode like the BAS416. |
| 06 maa 2016 23:13:29 | Arduino wattmeter | Wolfram Fischer | should i use shottky diodes instead or 2x 1n4148 in series? |
| 06 maa 2016 21:11:13 | Arduino wattmeter | Freddy | There is a small offset voltage present as you have noticed. This voltage is difficult to compensate, because it has not a steady value. The source of the offset voltage is probably the leakage current of the 1N4148 protection diodes. |
| 06 maa 2016 13:24:37 | Arduino wattmeter | Wolfram Fischer | Hi, i calibrateted the Wattmeter, it is very precise! But with no Voltage it shows -0.01V. Where can i fine-adjust it so it shows 0.00V? |
| 29 feb 2016 12:36:28 | Power measurement | Freddy | As shown in equation 4 beside figure 6: the calculations are done with the effective values of the voltage and current. The amplitudes that you mention are the peak values who are sqrt(2) higher. |
| 26 feb 2016 21:33:58 | Arduino wattmeter | Allan Lind | Freddy, yes I was considering that option as well, but the transmitter would be more useful if it has built in wifi and web server which you get with the ESP8266 module. I've ordered a couple of the NodeMCU modules and will try them out. |
| 26 feb 2016 18:27:13 | Power measurement | tom billiodeaux | I fail to follow your Figure 6 measurements mentioned of V = 8 and I = 6. without a scaling factor, the figure shows V = 12 and I = 8. Please comment. Good article and thanks for the effort. Tom Billiodeaux...337 945 7263 Mech. Engr. |
| 26 feb 2016 16:34:05 | Arduino wattmeter | Freddy | @ Amir The first comment on this article is about the necessary modifications when using the Arduino Uno. @Allan If you are transmitting the data to another location and display the parameters there, then you could do the floating point calculations also there. In that case you could remove the floating point calculations on the Arduino and send the int values. |