We'll send a beam of light into the sky, and it will blink as a digital signal.
Now, I’m going to explain what 'blinking as a digital signal' means.

However, the communication speed must be slow.
This is to prevent it from being used for malicious purposes.
A slow communication speed means that one has to stay in a certain location for a certain amount of time.
What I’m trying to say is that for bad actors, staying in one place for a long time is something they would strongly want to avoid.
 
I need to get ready for work now. 
I will continue this after I finish work. 
I should be done by 7:00 PM Japan Standard Time (JST).

I appreciate your help.
Thank you!
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Good evening, everyone in America!
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I’d like a battery.
The type shown on TED the other day was using a solar battery.
A solar battery, huh... I think that’s definitely the smartest way.
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By the way, how much does a solar battery cost?
We need to rack our brains here.

We have to make this with the lowest budget possible.
However, we must avoid losing reliability just because it's cheap.
This is tough...
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First, we need to create an idea of what kind of setup will allow us to establish communication.
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First, we need to generate electricity.
Using this electricity, we also need to convert the intensity of light into a digital signal.
Then, we need to display this digital signal as text.
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Let’s start by thinking about how to generate electricity.
You can even make your own battery.
Have you heard of a lemon battery?
 
Actually, you can also generate electricity by shining light on an LED.
I just checked the price of solar batteries.
Hmm... they're expensive...
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Can LED lights be used to generate electricity?