28 March, 2017

Yes! Air pollution today!

The air is so bad today!  I checked the AQI (air quality index) from the Taiwan Air Quality Monitoring Network, Environmental Protection Administration, Taiwan.

It has been criticized that AQI does not responsible for the "real" air quality. For example, the PM10 is reaching the very high-purple level when the concentration is over 101 micro-gram/m^3 according the Department for Environment Food & Rural Affairs, UK,

Yesterday, the AQI of Tauyuan was yellow, but the PM10 was about 90 - 95, was the brown level in the UK. However, the AQI in Taiwan cannot reveal such index.  

I have no power to improve the air pollution. What I can do is wearing a mask, and tell friends the air is very dirty now!

20 January, 2017

Teach my child: How to use a clamp meter to measure AC current of electric heater

I have used electric multi-meter for many year (perhaps since I was a junior high school student)

This is the first time I buy and use a clamp meter.

Figure 1  Got the batteries installed

Figure 2  A electric heater (1200 W) was connected to a self-made extension cord (I made it two years ago). The cord was consisted with two strains of wires (the hot and ground wires), and I separated them. Clamped one strain of the cord and measured the AC current.

Figure 3  Yes! the cute palms with red sleeves were my boy's hands!

After measuring, I confirmed that the heater was not always running with the maximum output (every night, we could hear "click" sounds from the heater ever 10 -20 seconds, and my wife thought that really noisy in the night).

From the clamp meter, I also the current changed from  8.5 - 9.0 A to 0.2 A about every 10 sec.  This is the noise come from.

I just guess that the switching sound is using a thermo-switch to prevent the device overheating.

In addition, I think the life skills are more important than any grades of subjects in the school. Thus I taught my child how to measure AC current, even he did not know what was he doing!

Fluke AC/DC clamp meter manual (in PDF)
Electrical wiring in North America - Wikipedia