月: 2021年2月

My another photo blog “LQ Laoshi’s Photo Gallery”(outside wordpress)

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Recently I made an electric device so that my mom could talk to me from her room to my room. However that device could not amplify my mom’s voice well. The reason was that sound level by the microphone unit was too low. So I needed to put a “Pre-amplifier” between the microphone unit and the main amplifier. I looked for it by amazon.co.jp. and ordered it. The issue was that it was not a unit but a kit. That meant I had to assemble many parts.

This was delivered yesterday.

The package was from a Japanese company. I would say what Japanese do is elaborate, maybe too much. The package is being put in thick plastic bag. There are a lot of detailed explanations on the sheet of paper, including the circuit diagram. The parts are neatly divided in three small plastic bags. Those elaborate things are basically good, but often ends up high price. This kit costed approximately 12 USD. I think that high prices and excess qualities are typical to Japanese products. It must be a disadvantage in current harsh international competitiveness.

So I needed to solder each parts one by one on the small circuit board.

This is the bottom side of the board. All the parts were soldered, but wires were not yet. I should say my soldering is not good becasue there was a poor soldering at one point. When I turned on this unit first, actually this didn’t work. I checked my soldering and found a poor soldering. I melted it again. And then this pre-amplifier became functional. I haven’t done these soldering electric parts for so long. This time was the first since the last time 30 years ago.

This is the top side of the board.

I put the pre-amplifier into the box. It seems as if the left space in the box would have been designed for the pre-amp unit from the beginning (Actually not).

And I put the device again on the column in my mom’s room. This time I put indications to tell her what the switch is and where the microphone is. My mom shows the early sign of Alzheimer’s disease. So for her it is difficult to learn anything new. She always try to push the volume control to turn on it, although it is not to push but to rotate. Anyway I have to tell her how to use this, on and on.

My another photo blog “LQ Laoshi’s Photo Gallery”(outside wordpress)

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My family is not wealthy by any means. However, our house, located in suburban, is a little bigger than those houses in urban area. I am always in my room on the second floor, doing PPT slides making for online Japanese teaching. My mom is in her room on the first floor. So when she calls me, she needs to come out from her warm room to cold corridor and shout my name aloud. I had been thinking about if there was any good way for her to call me from her room. I thought of making a device with a microphone, amplifier, long wire, and a speaker.

I bought several electric parts by amazon.co.jp. The solder was the only thing that I needed to go buy in DIY shop.

I forgot to take a photo while I was assembling. The device was finished as in the photo. Voice caught by condenser microphone is amplified by 6-Volt. And the speaker with 77mm diameter sounds at the end of the long wire—–If it could work as I designed. People may say “Oh, you should have arranged those parts a little more left in the box, because there is an empty space.” Yes, I thought the same thing when I finished assembling. But I would say, that empty space on the left will be used, liking it or not.

So I put this device on the cedar column in mom’s room. I wish that this device will not be disturbing when my mom puts the futon down in the night and puts it back in the morning.

My house is a kind of traditional wooden Japanese style building. So it is relatively easy to place a long wire from room to room and make a hole on the wall. This is a photo in my room.
But I found a big PROBLEM with this. The voice on the speaker is too small even in the maximum volume. In Japanese expression, this would be metaphorically said “voice of a mosquito’s weeping”
I know that the amplifier works well because I tested and confirmed that it could make sufficient sound volume before assembling. So the problem is on the microphone unit. The unit does not make enough gain for the signal that is coming from the microphone. I have already sent a question to the vendor through amazon, asking whether or not the mic unit output did not gain a good sound level such that can be connected to amplifier directly. I don’t expect that the vendor can answer my question soon because now is the time of lunar new year.
So I think that I need to add a “pre-amp” between the microphone unit and the amplifier. I will buy a pre-amplifier unit from amazon and place it in that empty space on the left in the box, probably.

Yesterday I went to a DIY shop by walk, to buy solder. On the way I found two swans when I was walking in rice fields area.