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Commit 103a1859 authored by Yamane's avatar Yamane
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week10 modified

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...@@ -398,7 +398,14 @@ NeoFade(50); ...@@ -398,7 +398,14 @@ NeoFade(50);
## measure the power consumption of an output device ## measure the power consumption of an output device
- insert a registor of 1 ohm before Neo Pixel LED as a shunt registor - insert a registor of 1 ohm before Neo Pixel LED as a shunt registance
Note: What is "shunt resistance"?
![shuntresistor.png](../images/week10/shuntresistor.png)
A shunt resistor is used to measure electric current, alternating or direct. This is done by measuring the voltage drop across the resistor because of its resistor having a very low value of resistance. Shunt resistance should be 1/1000 or less of the total resistance. It is explained in detail [here](https://www.rohm.com/electronics-basics/resistors/shunt-resistors).
- edit code which come to illuminate LED the blightest (parameter is 255 ) - edit code which come to illuminate LED the blightest (parameter is 255 )
```jsx ```jsx
...@@ -549,13 +556,22 @@ V=IR ∴ I=V/R=139.8/1 =139.8mA [2] ...@@ -549,13 +556,22 @@ V=IR ∴ I=V/R=139.8/1 =139.8mA [2]
→By doubling the light intensity, the current is almost doubled. →By doubling the light intensity, the current is almost doubled.
- calcurate Power Consumption - calcurate Power Consumption of shunt resistor
P255 = I×V =275.4mV × 275.4mA = **75.85μW [3]**
P128 = I×V =139.8mV × 139.8 mA = **19.54μW [4]**
calcurate the ratio of [3] to [4] which answer is 75.8 / 19.5 = 3.88
- calcurate Power Consumption of NeoPixels
Though I forgot to measure voltage of between VCC and GND on first neopixel, if it is 5V,...
P255=I*V =275.4mV *275.4mA = **75.85mW [3]** P255 = 5V * 275.4mA = 1377mW =1.3W
P128 = I*V =139.8mV *139.8 mA = **19.54mW [4]** P128 = 5V * 139.8mA = 699mw = 0.699W
calcurate the ratio of [3] to [4] which answer is 75.8 / 19.5 =**3.88**
## What I learned in this week ## What I learned in this week
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docs/images/week10/shuntresistor.png

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