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Do-it-yourself karaoke. Microphone Amplifier Assembly

Electronics / Sound and Acoustics
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Greetings the inhabitants of our site!
Today we will consider another project from the author of YouTube channel "Radio-Lab", namely, the assembly and connection of a microphone amplifier for karaoke.

The subject will be such a microphone from a home theater of an unknown brand.

The microphone is the most ordinary, and many, I am sure, also have it. To use it to the maximum, you need to connect it, for example, to a sound amplifier. But just as it is, of course you can connect a microphone to the amplifier, but there may not be the desired result. In order for everything to work correctly, the microphone needs its own microphone amplifier, which will amplify the weak microphone signal to the required level and then the received signal can be amplified without problems with a conventional sound amplifier.

One of the options for such a microphone amplifier, we now consider. The following circuit of a microphone amplifier based on the TL071 chip was found on the Internet:


This scheme is unipolar powered. The author developed a board for the future microphone amplifier.

This is how the finished board of the future microphone amplifier looks like:


All the necessary radio components can be purchased on the radio market or from Chinese comrades with Aliexpress:
- 6.3mm socket;
- Textolite F4 for boards;
- ESR tester;
- Amplifier TPA3116D2 2.1;
- Mortise sound module;
- Linear stabilizer L7812;
- Resistors.

All items will need to be installed on the board. There are not many details and there should be no problems with the assembly, the main thing in this matter is not to rush. Let's start assembling the microphone amplifier with the installation of constant resistors.

It is convenient to use such tester:

As you can see, the value of the resistor is about 10k, install it in its place.

We do the same with the rest of the resistors.

Permanent resistors installed. You could say that was the hardest part of the assembly. Next in line is a 22pF non-polar disk capacitor.

Then we install (always observing the polarity) polar electrolytic capacitors. A longer leg is a plus (+), and there is also a minus sign (-) on the body. In addition, denominations are indicated on the case.


Polar capacitors in place. There is one jumper on the board, it can be made from the trimmed legs of any component, for example, a capacitor.

Next - film non-polar capacitors.Just set it in place.


Next up is the LED. It has polarity. A longer leg is plus (+), a shorter leg is minus (-), respectively.

Then, using the key on the case, you need to install the chip.

Now the terminal blocks. They are the same, 3 pins.

Next is a variable resistor. He is alone, at 10k.

To expand the power range and functionality on the board, there is a place for installing a linear voltage stabilizer L7812 with an output of 12V.

This stabilizer does not interfere, but it heats up significantly during operation. Installation of a radiator is required.


Next, seal the 6.3mm jack for connecting a microphone.

For ease of adjustment, put the knob.

We wash the board from the flux and after the work has been done, we get a microphone amplifier, this is how it looks:


A variable resistor allows you to change the volume level of the microphone. At the back of the board are input contacts for supplying an audio signal (for example, from a mortise module or a telephone), and near the variable resistor there are output contacts for connecting, for example, to the input of a sound amplifier.

Now let's check the operation of the assembled board and check whether it will fulfill its task, namely to amplify the signal from the microphone. For the sound signal we will use here such a wire.

The microphone signals are the same for the left and right channels, in fact one mono signal. We feed the circuit from a battery with a voltage of 12V. Observing the polarity we connect the battery.

The LED is lit, therefore there is power. For tests, the author uses this column:

We connect the output from the microphone amplifier board to the speaker input and apply power. Now everything is ready for a performance test. We set the microphone volume on the board to the minimum position and connect the microphone.


Then we gradually increase the microphone volume (see the author’s original video for more details).

So, the assembled microphone amplifier works fine, then we will consider various possible schemes for connecting it.

1. Connect the assembled microphone amplifier to the sound amplifier board. We connect the power wires from the 12V battery and signal wires according to the following scheme:

For an example, the author used a sound amplifier board 2.1 based on two TPA3116D2 microcircuits with unipolar power supply. We connect test acoustics to the sound amplifier. But the functionality of the assembled board does not end there.

2. This board can work just like a microphone amplifier, or it can superimpose a microphone signal on music, and, therefore, with its help you can add the karaoke function.

We connect a mortise sound module to the sound amplifier. Using the microphone amplifier board, you can make it possible to connect a microphone to this assembly. The microphone amplifier board is included in the gap of the signal wires between the mortise module and the sound amplifier, or between the timbral block and the sound amplifier. The power of the microphone amplifier is connected in parallel to the power terminals of the sound amplifier. The assembly will be powered by a 12V battery in this case. Here is the connection diagram:

If you do not connect a microphone, then it will be a normal sound amplifier with MP3, radio and other embedded functions.

You can also use other similar ones, for example, stereo sound amplifiers with unipolar power.

The connection is exactly the same as that of the amplifier 2.1. For amplifiers with bipolar power, the microphone amplifier board is also suitable, but in this case it must be powered from a separate power source or from the plus power arm (ground and plus), if the supply voltage allows.

Inspection with a thermal imager showed the following picture. Most of all, the L7812 stabilizer on the microphone amplifier board heated up. It is warming up, but that's fine. If the heating is strong, then you will need to screw a larger radiator.

Here's a mic amplifier board. As you can see, there is nothing complicated, and if desired, this project is quite easy to repeat. Using this board, you can assemble an amplifier with the ability to connect a microphone, you can also assemble an amplifier with the karaoke function, stationary or portable on batteries, or add the ability to connect a microphone to ready-made devices (if it is technically possible to do this). In general, the application is essentially limited only by imagination and tasks.


Try and collect. Here LINK on the board drawing. Thank you for attention. See you soon!
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20 comments
+2
Reply To quote A complaint
"where the fuck with the bully. yes syphilis ....". (c) V. Mayakovsky "At the top of his voice."
... I also remember that ....
0
Reply To quote A complaint
That's right. I remember in our classroom a book with verses by V. Mayakovsky once walked through the ranks. And in it was a word beginning with the letter "B", and without any abbreviations. The most interesting thing is that the boy who brought the book to the lesson took it to read in the school library! goodgood xaxa They also let the teacher of the Russian language and literature read when she became interested in why everyone was laughing. yahoo
+3
Reply To quote A complaint
Apparently, the book is quite an old edition. Until a certain time among the classics, this word missed censorship. It is interesting that, say, in Pushkin's publications of different years, dots were replaced by more than the same words.
0
Reply To quote A complaint
We (more precisely, in Minsk) have electric buses on them)))). I myself was shocked when I found out that the “wireless trolleybus” does not drive on batteries, but on “supercapacitors”, charging at a stop ...
+2
Reply To quote A complaint
And I remember that it struck me that it was written in Peter the Great (Without any abbreviations !!!). “Is this what happens, Tsar Father?” Give your uncle your wife, and go to the whore yourself? ”...))))) ... I was shocked then, to be honest ....
0
Reply To quote A complaint
R555 We read carefully, delving into the meaning!
Microphone Amplifier Assembly
Recently tore like a scarf from some DVD, so there’s also an adjustment of the echo level, and for nutrition are ionistors
Your statements
Something I doubt ... Some kind of madness ... nobody will put ionistors on the microphone amplifier board, they have nothing to do there ... ionistors are on the main board, this is quite logical, most likely for the same as in videos
this is only your erroneous opinion. In terms of capacity, he cited the first thing that came across in the assortment of the Chip & Dip store in Moscow, I think in wholesale production the wholesale prices are much lower, this is about
greedy bourgeois put ionistors
By the way, in high-end equipment they are not so greedy! yes
0
Reply To quote A complaint
I mean, nobody will put ionistors on the microphone amplifier board, they have nothing to do there (and you wrote that you ripped a similar board from the DVD, it also has an echo level control). But, if the ionistors are on the main board, this is quite logical, most likely for the same as in the video recorders.

P. S. It is curious that you first wrote that there are ionistors with a capacity of 2.2 F, and then you wrote about 3.3 Farads and, as usual, indicated the price. Or is this for example, i.e. not regarding that specific board?
+2
Reply To quote A complaint
In the library book "The Tale of Tsar Saltan ..." after the lines

“The queen gave birth to the night
Not a son, not a daughter;
Not a mouse, not a frog,
And to the unknown animal. ”
Someone on the sidelines gave an explanation, "Cheburashka."
0
Reply To quote A complaint
R555
Something I doubt ... Some kind of madness ... Another thing when to me I came across ionistors, for example, in video recorders
When You, in ancient VCRs, of course, is another matter, but when it is different, in more advanced home theaters, it is of course, some kind of madness! xaxa
+1
Reply To quote A complaint
I recalled reading in school a novel called Virgin Soil Upturned.
- I re-read it recently. Masterpiece. One grandfather Shchukar what is worth.
0
Reply To quote A complaint
Something I doubt ... Some kind of madness
Just the device came across a serious manufacturer.
VEC3R0335QG, 3.3 Ф, 3 V, 8x20, Ionistor 130 rub
yes
+1
Reply To quote A complaint
R555
Yo-mobile. And that ...
It was recalled that I read the novel “Virgin Soil Upturned” at school, there in dialogues, in “strong” expressions, someone carefully wrote letters over dots, apparently so that the girls could understand! xaxa
+1
Reply To quote A complaint
Does anyone know, maybe someone bought it?
- As far as I remember, one such car Prokhorov gave Zhirik
0
Reply To quote A complaint
More about ionistors. Two years ago, the theme of creating a domestic electric car was discussed. At one time I was tracking this topic, but then I got tired. There was even a competition for the best name for this car. And the masterpiece of insanity was the name "E-Mobile." And that ue ... was created, as I understood then, on the basis of ionistors. People, like, in the queue began to sign up for it ... well, they understood. So what? How many pieces came off the assembly line, how many were sold? Does anyone know, maybe someone bought it? Curious to know the reviews, first of all, what is the mileage on a single charge?
+2
Reply To quote A complaint
He asked about the ionistors and remembered the case. A very long time ago, when I was in school, nobody even heard about ionistors, not that I saw them. Then, capacitors with a capacitance of several thousand microfarads were rare and their sizes were 10 times larger than modern ones.

But I read in some journal, most likely, “Science and Life” that scientists came up with a new device called an ionistor. And that his capacity is somewhat Farad, which exceeds the capacity of the globe.

Well, I took this journal with me to school and at a physics lesson I told the teacher about this invention. The teacher said that this is nonsense, that the huge globe also has a smaller capacity. And I take it, and show me the article. The teacher read and blushed deeply ... It turned out that his knowledge was 25 years late. xaxa After this incident, the teacher of month 2 did not call me to the blackboard - suddenly I would ask something new, but he again did not know ... yahoo
0
Reply To quote A complaint
Something I doubt that greedy bourgeois put ionistors in the power filter of the microphone amplifier. How before, before the widespread use of ionistors, dispensed with conventional electrolytic capacitors? In this circuit, it would be possible to use penny microfarad capacitors so at 1000. Why did they put the ionistors there as much as 2.2 Farads ??? !!! Some kind of madness. fool It’s very interesting to know why. Can you show a photo of the board?

Another thing is when I came across ionistors, for example, in VCRs. There they were set so that the clock and timer would not be reset when the mains voltage disappeared.
0
Reply To quote A complaint
R555
what do ionistors do in a shawl torn from a DVD?
They are jammed by power, microphones are electrodynamic. yes
0
Reply To quote A complaint
echo level adjustment


PT2399, on this mikruh you can get a good guitar delay or reverb.
0
Reply To quote A complaint
I do not understand what the ionistors do in a scarf torn from a DVD? smiles
0
Reply To quote A complaint
Variable resistor allows you to change the microphone volume
Recently I ripped a similar handkerchief from some kind of DVD, so there is also an adjustment of the echo level, and 2.2F ionistors stand for power, although this is superfluous when powered by a battery.

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