[tlug] Power Supplies (in Japan and Traveling) (was Re: Importing WiFi equipment)

[jep200404@example.com]

Shmuel Fomberg wrote:

> Of course, the power supplier is a problem.
> 
> Is it possible to go to Akiba with a power supplier at hand, and find 
> compatible supplier for the Japanese current?

It is possible. However, I think it is better to acquire what 
you need _before_ you travel. You might already have what you need. 

For wall wart power supplies, it used to be that most of them 
used line frequency transformers. Those were designed for a 
particular voltage and frequency. However, switch mode power 
supplies (SMPS) have become common. One of the beauties of 
SMPS is that it is easy to design them to work over a wide 
range of voltages and frequencies. Look at the fine print on 
a power supply. You want one that will work with any input 
voltage from 100 VAC to 240 VAC at either 50 Hz or 60 Hz. 
Let's call such a power supply a "universal power supply".  
Almost all laptop power supplies made for the last twenty 
years have been universal power supplies. (That includes Scott's 
wife's netbook from last year.) Ten year old wireless routers 
almost always came with (non-universal) line frequency power 
supplies. There was a change to where most of them come with 
SMPS now. My feeling for the 50% change over was about five years 
ago. Not all SMPS are universal. Read the fine print. 

In my travels, I have to deal with 100 VAC, 120 VAC, and 240 VAC. 
I also have to deal with both 50 Hz and 60 Hz. In the old days, 
I used the travel adapters. Now, I have universal power supplies 
for everything. All the plugs are the same style. I plug everything 
into an outlet cube or outlet strip (that does _NOT_ have surge 
protectors). Then if needed, I have a single plug adapter 
for wherever I am. The plug adapters are the only special equipment 
I need for each place. Plug adapters are small and cheap. 

On my last trip, I was at a factory that made stuff for export 
to the world. There was the native voltage, and they had a big 
variable transformer for testing with foreign voltages. I had been 
using my stuff for days on the native voltage. It was fun to 
watch the fear on their faces when I plugged my stuff into the 
foreign voltage. Of course, my stuff just worked without incident. 
It just did not care whether the voltage was 100 VAC, 120 VAC, or 240 VAC, 
50 Hz or 60 Hz. 

It is possible that you already have the kind of power supply that 
you need. Please post a URL for a picture of the labels on your 
power supplies that you are concerned about. 

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SMPS are also more efficient than power supplies that use line 
frequency transformers. So for things that are on all the time, 
I started replacing power supplies that use line frequency 
transformers. I troll thrift stores for used electronics, 
especially universal SMPS wall warts. Small ones are usually less 
than €1, and big ones (like for laptops) are usually €2 to €4. 
I take a magnifying glass to read the fine print, which can be very 
fine indeed.