Making “Pre-Amplifier” between Microphone and the Main Amplifier

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

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 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.

Mic on the 1st Floor and Speaker on the 2nd

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

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 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.

Weekly Logs: Jan. 25-31, 2021

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

I haven’t recovered from fatigue that had accumulated by hard work in the last semester. Most of the time I couldn’t get up from my bed even in daytime. Nonetheless the university forced me to work for scoring “Contest”. I worked for about 16 hours in total for evaluation each student’s performances.

Now the first year anniversary day of my dad’s death is approaching. Although numbers of the expected participants to the ceremony are small, I ordered return presents for those people. They are all elders and trying to come through bad weather of the middle of winter. I thought I had to choose good presents for them. I went to the only department store in the city to make the order. While I was looking at the gift catalog at the gift corner in that department store, the clerk lady didn’t want me to be there for long. So I left there with the catalog, got back to my house, and let my mom choose the present. That was on Thursday, I had to go there again to fix the order on Sunday. Two times of go-and-back required me to pay for JR-train, of course the department lady didn’t care about such things, Okay, those were good excursions for me.

The main dish for Monday supper was Mackerel boiled with soy sauce; Fried sliced pork on Tuesday, Soba noodle with Tempura on top on Wednesday, Leftovers of lunch that was Chinese food on Thursday, Grilled salmon slice on Friday, Chicken thigh boiled with soy sauce on Saturday, and grilled salmon slice again on Sunday.

I put a small wooden plate so that the pigeon could rest on it without being hit by snow fall.

Weekly Logs: Jan. 11-17, 2021

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

January 11, Monday
I used two hours in the morning for posting the last week’s log here in the morning. I worked for six hours in the rest of the day. The main dish in supper was boiled fish.

January 12, Tuesday
I cleared snow in the morning, worked for four hours, and went to a library and supermarket. I cooked curry for supper.

January 13, Wednesday
I worked for ten hours. That was preparation for the Japanese business manner class in coming spring semester. I cooked pork for supper.

January 14, Thursday
As was the day before, I worked for ten hours to prepare for the business manner course. I went to the library in the afternoon by walk. The main dish in supper was grilled salmon.

January 15, Friday
I got to know that the university would make me work even in the winter break.

January 16, Saturday
I went to Niitsu 1st-6th morning market in the morning to buy Kimchi from Ms.Yamashita. Since I wouldn’t like to work, I spent most of the afternoon by internet-surfing.

January 17, Sunday
I worked all day as usual to prepare for spring semester. Now my concern is whether or not I will be able to be ready for the coming spring semester because the university is going to make me work for an additional task during this break, which I didn’t predicted.

Weekly Logs: Jan. 4-10, 2021

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

January 4, Monday
One and a half hours were spent for posing the last week’s log here in the morning. The rest of the morning hours were used for reviewing my scoring of the final exam for reading class. I just made scoring on image files captured from PDF because I could not get students’ real answer sheets in paper format. Once I finished reviewing, I started the second check by inputting students’ answer one by one into a big spread sheet of excel in the afternoon. After the supper, I made some tables of my grading so that it would help me input grading on online registering system. I went to bed at 10:30p.m.

January 5, Tuesday
I started working in the morning. That was to register my grading for the students’ performance in the fall semester. But when I was still doing that, the system had become stopped its function. I knew that the capacity of that registering system was very limited. So I just thought I would do that later. And then I went to out and got on a local train. I needed to get rid of snow in a house. Now the house doesn’t have a person to manage. If there was snowfall, the path from the road to the entrance would be completely covered with snow. It took two hours to make a path by digging and throwing snow with heavy steel shovel. It made me tired. I went to bed at 8:30 p.m.

January 6, Wednesday
I just wasted my time in the morning. Probably it was partly because I was tired from the hard work in the fall semester and mostly because I couldn’t even open the web page for the online registering system for the students’ grading. It seemed that I could not complete registering by the deadline. I took a long nap on the bed in the afternoon. I woke up and then went out. I got on a local train to go to Niigata. I bought a mouse in the electric appliance store by the JR Niigata station. I got back my house at 5:30 p.m. I cooked supper. The main dish was boiled flat fishes with soy sauce.

January 7, Thursday
Since I couldn’t register myself the students’ grades online, I asked the chief to register them on behalf of me. Although I asked the task, I myself had to used the whole morning hours for this to be done. In the afternoon I started preparation for the coming spring semester. I tried making the course design for the business manner class for the third grade students. I cooked salmon for the supper, practiced my bass an hour, and then went to bed at 8:30 p.m. I usually read an English book on the bed until I feel asleep. For this kind of reading a foreign language book, I think it is common not to use a dictionary. But this time I try to use my CASIO electronic dictionary as much as I can understand meanings of English sentences. There are a lot of words that I don’t know. A lot ‘n’ lot. Never is there an end for the second language learning.

January 8, Friday
I didn’t work in morning hours. I just rip music from my music CD and saved them in my Sony Walkman that was mp3 music player. Let me say this; the CDs were that I bought by my money. The mp3 player is for me to listen. So there is no copy-right violation because it is sheer personal use only.
In the afternoon was as follows; I took a nap for an hour. I went to a supermarket to buy foods. I revised the course design for business manner class. I cooked chicken for supper. I recorded my voice so that my students could improve their listening. I practiced my electric bass for an hour. I went to bed at 9 p.m. And then I fell asleep with the help of reading an English book.

January 9, Saturday
We had got a lot of snow in this winter. I got rid of snow a little in the morning. And then I reorganized picture files on my another photo blog on “goo”. This task used two hours of my time in the morning. In the rest of the day, I had just worked for recording my reading voice to make listening materials for my students. The main dish of supper was the slice of mackerel grilled simply with salt.

January 10, Sunday
I worked hard in the morning. But that work was not as a Japanese teacher but as a labor to clear snow. Not only for my house, I made a path for the community although it was just a ten meter or so. I was exhausted. After I finished and I was taking a little rest, I heard a sound of a heavy machine coming. It was a big snowplow probably hired by the city. In a few minutes, the machine had done what I could never do with my hands. It was just like go-and-back, and then the work had done. No sign remained that indicated I worked hard to get rid of snow before the machine came.
But that was not the end of my fight against snow. The air-conditioner as a heater in my mom’s room didn’t work. I was not sure for the reason, but I guessed that the outdoor unit was buried in snow and it could stop the fan rotation. Snow depth was already more than one meter (three feet). I dig the snow and reached the unit. As I expected, snow and ice piled up and went into the unit. They were preventing the fan from rotating inside. What I needed to do was simple; to get rid of them. But the problem was that I couldn’t remove the big circle like mesh lid on the surface of that Hitachi made air-conditioner outdoor unit. I used hot water in a kettle, a long chop stick, and even plastic straw to remove or melt the snow inside from outside through the meshed lid. I blow my breath through a straw in order to melt the snow that was sticking on the fan. Actually this method didn’t work well. I confirmed the fan could rotate, then turn on the AC. I found that that sent a warm air. It took two hours.
In the afternoon, I took two hours of nap on the bed, I went to the library by walk to return books and borrow new ones. Back in the house, I continued recording my reading a textbook for business manner course. I cooked pork for the supper.


This is a test positing as a preparation for Japanese course ‘Business Manner’ that will be taught in coming spring semester.
The posts under this category will be written in Japanese.
I am sorry to say that this post doesn’t have any useful information to you.

Weekly Logs: Dec.28,2020 – Jan.3, 2021

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

December 28, Monday
I posted the last week’s log on worepress in the morning. And then I went out and got on a train for shopping in Niigata. I bought a 21.5 inch PC monitor at the big appliance shop on the south side of JR Niigata station. Now I am typing this by looking at my new monitor, I think I should have bought the bigger screen much earlier because my eye is already tired of looking at a small screen of notebook PC for these two years. And 23 inch or even 27 inch would have been better to buy, I just regret that. Back to my home before 1 p.m., I had a lunch, went to a supermarket, took a long nap, and cooked supper. After eating supper, I evaluated test results of the final examination for conversation class. I evaluated three pairs before going to bed.

December 29, Tuesday
Of course I had to give scoring for the final exam, but I didn’t start doing that in the morning. Instead, I started cutting a timber (lumber?) plate in the morning. I wanted to make two speaker boxes in order to listen to music in good sound. But it was obvious that I could not complete two speaker boxes in one day. So I just stop the work at noon. I took a nap a little while just after the lunch and then went to a supermarket. I just graded the final examination of conversation class in the late afternoon. That grading continued after supper until going to bed.

December 30, Wednesday
In the morning I started the rest of the work for making two speaker boxes. The hardest part was to make two holes to set the speaker. The diameter was 94 millimeter. Since I didn’t have any cutting machine or drill, I did that using primitive tools; a gimlet and small chisels. It tool many hours, so it was 4 p.m, when I fit two boxes on the wall of my room. My supper on the day was chicken breast. After supper I evaluated three pairs for the final exam of conversation class.

December 31, Thursday
I cleaned the room with vacuum in the morning. It was because I just didn’t want to work for the examination scoring. And the day was the last day of the year 2020. I thought that the supermarket would be congested with people who wanted to buy food for new-year holidays. So I went to the supermarket just after the shop’s opening. There were less people there shopping. It was what I predicted, but it also made me worry if the supermarket could survive or not because there were less people even in the last day of the year. Anyway, I had to use all of the rest of the day to evaluate students’ final exam for conversation class.

January 1, 2021
The colleague sent me PDF of the answer sheets in the morning. That was of reading class and the exam was conducted the day before. So I wanted to start scoring soon, but I hadn’t finished evaluation about students’ performance during the semester. I spent most of the day to complete the evaluation, although I took two hours nap in the afternoon. After supper I started scoring the answer sheet of reading class examination. I practiced my electric bass for an hour, and went to bed.

January 2, 2021
All day was spent for scoring the final exam for the reading class. I evaluated 17 students. I was actually disappointed by some of students’ answers. Some students used the postposition “-ga” for objects, which was actually to be used for subjects. One student didn’t understand adjective conjugation when the adjective works as adverb. That was my responsibility for teaching those things. Students’ answer simply meant that I failed to teach them well. Thinking like that, scoring didn’t move on to next student. I gave up scoring at 10 p.m. with seven students remaining.

January 3, 2021
Being tired of working, scoring was not proceeding well. I spent all day for scoring the final exam only for seven students. After supper I found that I had to change scoring criteria and redo the scoring again for some reasons (I cannot write the reason here). The gradings need to be registered by January 6th on Wednesday. I have to continue to work until I register all the gradings of the students by that time.