• Transistor amplifier: types, circuits, simple and complex. DIY amplifier: master class on building a simple and effective device for signal amplification

    Factory-made devices for amplifying the audio signal are expensive and may not be powerful enough. Looking at photos of homemade sound amplifiers, it is obvious that they are in no way inferior in appearance to finished products. In addition, their manufacture on their own does not require special skills or large material costs.

    Device base

    Beginner radio amateurs first of all ask themselves: what can they use to assemble a simple sound amplifier at home? The operation of the device is based on transistors or microcircuits, or a rare option is possible - on lamps. Let's take a closer look at each of them.

    Microcircuits

    The TDA series microcircuit and a similar one can be purchased in stores or you can use a microcircuit from an unnecessary TV.

    Using car amplifier chips with a 12-volt power supply, it is very easy to achieve high-quality sound without the use of special skills and with a minimum of parts.

    Transistors

    The advantages of transistors are low power consumption. The device produces excellent sound performance, is easily integrated into any equipment and does not require additional configuration. In addition, there is no need to search for and use complex microcircuits.

    Lamps

    Today, the outdated assembly method based on tubes provides high-quality sound, but has a number of disadvantages:

    • increased energy intensity
    • dimensions
    • cost of components

    Recommendations for properly assembling a sound amplifier with your own hands

    A device for enhancing sound quality, assembled at home based on TDA series microcircuits and their analogues, generates a lot of heat. For cooling, you need a radiator grille of a suitable size, depending on the model of the microcircuit itself and the power of the amplifier. There must be a place for it in the case.


    The advantage of a self-made device is its low energy consumption, which allows it to be used in cars by connecting to a battery, as well as on the road or at home using a battery. Power consumption depends on the required degree of signal amplification. Some manufactured models require a voltage of only 3 Volts.

    We take a serious and responsible approach to assembling a sound amplifier in order to avoid short circuits and failure of components.

    Required materials

    During the assembly process you will need the following tools and components:

    • chip
    • frame
    • capacitors
    • power unit
    • plug
    • switch button
    • wires
    • cooling radiator
    • screws
    • hot glue and thermal paste
    • soldering iron and rosin

    Circuits and instructions for making an amplifier at home

    Each circuit is unique and depends on the sound source (old or modern digital technology), power supply, and expected final dimensions. It is assembled on a printed circuit board, which will make the device compact and more convenient. During the assembly process, you cannot do without a soldering iron or soldering station.

    The British John Linsley-Hood circuit is based on four transistors without microcircuits. It allows you to similarly repeat the shape of the input signal, resulting in only pure gain and a sine wave at the output.

    The simplest and most common option for manufacturing a single-channel amplifier is to use a microcircuit based on it, supplemented with resistors and capacitors.

    Algorithm of actions for production

    • install radio components on the printed circuit board, taking into account the polarity
    • assemble the body (providing space for additional parts, for example, a radiator grille)


    It is permissible to use a ready-made case or create it yourself, as well as install the board into the speaker case.

    • run the device in test mode (identify and eliminate malfunctions if they occur)
    • amplifier assembly (connection to the power supply and other components)

    Pay attention!

    DIY home and car amplifiers

    At home, there is often a lack of powerful sound when watching movies on a laptop or listening to music on headphones. Let's look at how to properly make a sound amplifier with your own hands.

    For laptop

    The sound wave amplifier must take into account the power of external speakers up to 2 watts and the winding resistance up to 4 ohms.

    Assembly components:

    • 9 volt power supply
    • PCB
    • chip TDA 7231
    • frame
    • non-polar capacitor 0.1 µF - 2 pcs.
    • polar capacitor 100 µF
    • polar capacitor 220 µF
    • polar capacitor 470 µF
    • constant resistor 10 Kom m 4.7 Ohm
    • two-position switch
    • input socket

    Manufacturing scheme

    The assembly algorithm is selected depending on the selected scheme. It is necessary to consider the appropriate size of the cooling radiator so that the operating temperature inside the case does not rise above 50 degrees Celsius. When using a laptop outdoors, you need to provide holes in the case for air access.

    For car radio

    An amplifier for a car radio can be assembled using the common TDA8569Q microcircuit. Its characteristics:

    • supply voltage 6-18 volts
    • input power 25 watts per channel into 4 ohms and 40 watts per channel into 2 ohms
    • frequency range 20-20000 Hz

    Pay attention!

    It is imperative to provide, in addition to the circuit, a filter against interference created by the operation of the car.


    First, draw a printed circuit board, then drill holes in it. Then the board must be etched with ferric chloride. After tinning and soldering all the parts of the microcircuit. To avoid power additives, a thick layer of solder will need to be applied to the power traces. Provide a cooling system using a cooler or radiator grille.

    At the end of the assembly, it is necessary to make a filter against interference from the ignition system and poor noise insulation according to the following scheme: on a ferrite ring with a diameter of 20 mm, wind a choke with a wire with a cross-section of 1-1.5 mm in 5 turns.

    Assembling a device to improve sound quality at home is not difficult. The main thing is to decide on the circuit and have on hand all the components from which you can easily assemble a simple sound amplifier.

    DIY sound amplifier photo

    Pay attention!

    We have repeatedly cited schemes powerful amplifiers low frequency power for self-assembly, and today we will talk about the design of a fairly simple, but high-quality and painfully powerful amplifier for lanzar scheme. At all, scheme Lanzara has found wide distribution on the Internet, more and more often people are repeating this design, due to its high performance and relatively simple and cheap assembly, the circuit has begun to be used in industrial audio equipment.

    Lanzar is implemented on 13 transistors, the circuit is completely symmetrical.
    The output stage of the amplifier operates in class AB, the minimum coefficient of nonlinear distortion allows the amplifier to be classified as hi-fi. Such an amplifier is also excellent for powerful broadband speaker systems, but due to the relatively simple circuit decoupling and high output power, the amplifier is often used to power quite powerful subwoofer heads.

    The peak output power of this amplifier is 390 watts into a 4 ohm load, but the amplifier also works great with low impedance loads down to 2 ohms.

    The archive contains a fully working printed circuit board for this amplifier.

    Assembly begins with etching the printed circuit board. For etching, I use a solution of hydrogen peroxide (3 percent solution, which is sold in pharmacies, 100 mg bottles), citric acid and table salt. The board is etched in a maximum of an hour, after which you need to wash off the toner and drill holes.

    Installation begins with installation small components - resistors, zener diodes and ceramic capacitors. I advise you to carefully check all components before assembly, even if they are completely new. Afterwards we solder the low-power transistors of the differential stages - where the initial sound is formed.

    ———————— The coil is wound on a frame with a diameter of 10-12 cm with a 0.8 mm wire and contains 10-12 turns, the coil can even be removed, this will not affect the sound in any way.

    The input capacitor must be film; the capacitance can be selected in the range of 1-4.7 µF, since the amplifier was originally intended for a subwoofer, and by increasing the capacitance of this capacitor, the best reproduction of low frequencies (bass) can be achieved.

    After complete installation of all components, wash off the rosin from the back of the board. You CANNOT use all kinds of fluxes for soldering with unknown content, since they are often acid-based, and it is because of the flux that you can burn the entire circuit. We reinforce the power paths with tin to prevent them from burning out.

    It is advisable to tin all the board tracks before installation, since copper sooner or later oxidizes, and the tin layer forms additional protection.

    Check carefully correct connection of transistors, electrolytes and zener diodes; to avoid problems, you should use only those transistors that are indicated in the diagram, especially if you are a beginner or assembling a lanzar circuit for the first time. If zener diodes are connected incorrectly, they will not stabilize the voltage, but will begin to work like a diode and problems will begin, smoke, explosion...

    After checking that all components are connected correctly, the amplifier can be started.
    Lanzar, like any other powerful ULF circuit, is powered by a bipolar voltage source. The input voltage rating can be from bipolar 25/30 to 75 Volts, but I don’t recommend running it at maximum, so power supply +/-50 Volts is the most suitable input power rating.

    —————————- To initially launch the circuit, you need to have a power supply on hand for the specified voltage, the power of the unit is 100 watts (although to run the amplifier at full power you need a power supply with a power of 300-400 watts.

    The transformer is connected to a 220 Volt network through a 220 Volt 100-150 watt incandescent lamp. The lamp serves as additional insurance; in case of problems, burn fewer components. It should be noted that for normal operation of the power amplifier after the diode rectifier, you need a good block of capacitors, the total capacitance of all capacitors in one arm should be 10000-30000 μF, the capacitor voltage is preferably 100 Volts (with a double margin).

    We select limiting resistors for powering the differential stage based on the supply voltage according to the table below.

    Power supply ±70 V - 3.3 kOhm...3.9 kOhm
    Power supply ±60 V - 2.7 kOhm...3.3 kOhm
    Power supply ±50 V - 2.2 kOhm...2.7 kOhm
    Power supply ±40 V - 1.5 kOhm...2.2 kOhm
    Power supply ±30 V - 1.0 kOhm...1.5 kOhm

    Select limiting resistors with a power of 1-2 watts.
    The first start-up of the amplifier is done with the INPUT SHORT-COVERED TO GROUND, do not confuse the ground with the minus! - ground, this is the midpoint from the transformer.

    To begin with, there is no need for heat sinks for the terminals. We connect the transformer to a 220 Volt network, if there are no pops or special effects, then turn off the power and check the heat dissipation by touch on the field keys; if you don’t feel anything, then we unsolder the input from the ground and play music, for starters from a mobile phone. We turn on the amplifier again, if the music plays, then everything is ok.
    For maximum power the input needs to be supplied with a signal from a more powerful sound source; the car radio is just such a source.

    We turn on the amplifier with music for 10-25 minutes at 40% volume, then it’s time to adjust the quiescent current of the output stage, a photo is attached for this.

    Thus, we have finished assembling the amplifier, we can rejoice, because an amplifier of this kind costs a lot of money, after all, buying is one thing, but making your own amplifier with your own hands is quite another.

    Archive for the article...DOWNLOAD...

    This amplifier can be ordered - [email protected]

    Sincerely - AKA KASYAN

    It was a long time ago, I decided to write only now.

    S-30B speakers were available.
    I wanted to make home speakers for my computer. The amplifier was missing.

    Went shopping. The lowest price for low-power amplifiers/receivers (30 watt speakers at peak) is about 6,000 rubles.

    I decided to do it myself.

    Tube - for audio flows, and there are a lot of problems. Transistor ones take a long time to set up, and the element base must be selected precisely, because errors in parts sold in markets and stores sometimes reach up to 10%.

    In the end, the choice fell on microcircuits.

    After Googling and reading the forums, I chose the TDA2050 chip.

    Connection diagram:

    As you can see, the body kit is minimal.

    They also need radiators.

    I took 500 rubles. and moved towards radio markets and shops.

    The entire element base cost a little more than 100 rubles.

    A power source was also needed. I won’t go into details about nutrition. Diode bridge + output connectors - about 100 more rubles.

    I bought radiators on the market from an old stump, 2 pieces for 20 rubles each.

    I bought some other little things, which will be discussed below.

    Returned home. We need to make stamps. I decided not to bother for a long time. I took out a piece of PCB from the bins, marked out the paths, and drew them by hand with a marker, as shown in the photo below.

    I etched it with ferric chloride (again, I got it from old supplies).

    I decided not to drill the signet, but to solder the parts on top of the tracks.

    The power supply is a little more responsible. Here, however, I drilled through the PCB, because the condensers are large and if you solder them from above, the mechanical load on the copper foil will be large and may peel off. Well, + stabilizers for +-12 volts, just in case, for the future I attached them to ordinary zener diodes + a transistor with a resistor;)

    About the transformer a little later.

    I connected everything with a canopy. Connected the sound source and speakers. Stop self-excitement. It beeps and that's it. I soldered 100nan film mikruh conders directly to the power legs. The excitement is gone. I ran it for an hour and it worked.

    Now the body.
    There was an old Vega 10U-120S lying around (the transformer was made from it)

    I threw everything out of him except the trance.
    I cleaned off the silver and put a plate on the front panel. I painted everything (the usual spray paint remained matte).
    This is what happened. (I made it 2 years ago, so it’s already shabby):

    The power supply was plugged into the place of the 2 condensers that were there:

    The volume control is a regular 2 kilo-ohm variable:

    I screwed the amplifiers onto 1 bolt. They are lightweight, so they hold securely:

    I once bought a regulator (variable) knob for 10 rubles:

    Wires for audio signal: I bought 2 meters of microphone cable for 30 rubles per meter.

    Everything started to look like this:

    On the back wall there is a socket for the input signal and output terminals.

    Twisted. Connected the computer and speakers. Everything worked immediately and without any complaints.

    I'm not a big sound connoisseur. To my ears, it plays no worse than what is sold in the store at a price of 6-10 thousand rubles. But it’s definitely better than it was when this amplifier case had its original guts. The high-rises appeared normal, the bass more or less cut through. It was probably bad due to the dried out old conder in the old offal.

    In general, after all this was ready, from 500 rubles there were 30 rubles left. All this taking into account travel from shops to shops.

    After some time, I picked up a Magnat Monitor Sub 200 A subwoofer (at that time it cost me 5,000 rubles). But this is already a conversation about acoustics and a different topic.

    Since then I have never complained about the sound. Everything works flawlessly. Enough for background music and for movies and for parties so that the neighbors can listen.

    p.s. This story happened a long time ago, so some people could have lied a little at some points.

    If you don’t want to spend money on expensive audio gadgets, you can try building a car amplifier with your own hands. This operation is not at all difficult. The main thing is to approach its implementation competently.

    1 Amplifiers - how not to get confused in their classes?

    Many audio systems in modern vehicles are equipped with a special built-in device that allows you to achieve greater sound volume and music quality. Unfortunately, such a standard car amplifier does not always cope with its tasks. Its power is simply not enough. In such cases, you have to purchase another device that can increase the current and voltage of the sound signal to a certain level.

    Nowadays it is easy to purchase almost any car amplifier that is more powerful and of higher quality. The only question is how much you plan to pay for this device, which is important for lovers of good music. Car amplifiers for reproducing high-quality sound are usually divided into different classes depending on the purity of the signal they produce and the efficiency indicator.

    A minimum of distortion is ensured by a car (relatively inexpensive) class A amplifier. But its efficiency does not exceed 20%. B-class devices are more powerful. Their disadvantage is a significant distortion of the reproduced music. The golden mean in this case can be considered class A/B devices. They are characterized by average values ​​of sound purity and useful action.

    Car amplifiers of the indicated classes can have a different number of channels - from 2 to 5:

    • three-channel audio devices allow you to connect two speakers to them;
    • in two-channel car devices, only speakers can be connected;
    • four-channel ones can operate in tri-mode (one mono and two stereo systems are connected to one output), and a subwoofer is additionally connected to five-channel ones.

    There are also high-power bass amplifiers. They are called monoblocks. The cost of such devices is high. Therefore, a monoblock car amplifier is purchased quite rarely and by those car owners who are not used to saving on anything.

    2

    When choosing a modern car amplifier, you first need to decide on its class, and then on the number of channels. And only after that begin a substantive analysis of the technical capabilities of the audio device you are interested in. How to choose a car amplifier in practice? Pay attention to the following characteristics:

    In addition, it makes sense to understand the number of car amplifier connectors. Expensive devices have a variety of linear and high-amplitude inputs. The first ones are necessary for connecting equalizers, processes and other systems to the audio system. And without the latter, you will not be able to install a radio in your car without a linear output.

    3

    Experts in the field of radio electronics say that transistor and microcircuit audio amplifiers cannot be compared with ULF devices in terms of the quality of the sound produced. Any pro will tell you that a tube car amplifier will delight you with excellent music without any distortion.

    At the same time, you can assemble such a sound amplifier with your own hands in a couple of hours and with minimal financial costs.

    Tube amplifier

    A tube auto amplifier can be made using a simple single-ended circuit. It is shown below. This circuit is good in that it allows you to increase the output power due to the parallel pairwise arrangement of light bulbs working on the load.

    Let's see how to assemble a simple car amplifier at home using the diagram below. You need to take the audio output and power transformers from the old TV, find (or purchase) an unused power supply and light bulbs. It is advisable to place products marked 6N2P at the entrance. And a 6P14P lamp is more suitable for the output. If you cannot find an old power supply for a homemade car amplifier, you will have to buy a new device. Choose any. The main thing is that it is designed for 50 Hertz and has windings for the specified voltages.

    Focusing on the diagram, you assemble all its elements into one whole (as you yourself understand, without knowledge of the basics of radio electronics it will be difficult to do this). Then you look for a suitable housing to house a homemade car amplifier. As such, you can use an unnecessary case from the system unit. You don’t even have to remove the fan from it - it will blow on the tube amplifier. The fan should not run continuously. Therefore, be sure to make a switch for it. Place this device on the back of the system technician's case. You will turn it on only as needed.

    Tube amplifier

    You can make your car amplifier more elegant and practical by illuminating its bulbs with multi-colored diodes. Then, when the audio device starts, the lamps will glow, for example, green, in standby mode – blue, and so on. That's all the wisdom of self-assembling a simple amplifier for a car. Believe me, it will not differ much from an average-priced factory device, and will even surpass it in sound quality.

    4

    Semiconductor elements make it possible for any craftsman who has the skills to perform simple electronic work to make a small semiconductor amplifier for his car. Let's see how to build an excellent audio device using the TDA8560Q chip. Instead, you can use TDA2005, TDA1558, and any other circuit that produces the following (approximately) characteristics:

    • frequency range – from 20 to 20000 Hertz;
    • power (output) – 25–40 W;
    • power supply (voltage) – from 6 to 18 V.

    To make a car semiconductor amplifier, you need to purchase all the required elements: capacitors and resistors (0.2 μF), a transformer (power) with a current of up to 5 A, a cooling radiator, a power switch, sound balance and volume controls, diodes marked D245 ( or their analogues), capacitor (electrolytic) 25 V x 4700 µF, connectors (output and input). You assemble all these components according to the circuit on a printed circuit board, solder them, and solder a thin wire into the power traces. Then mount the manufactured structure on the cooling radiator. Your little sound amplifier is ready!

    Auto amplifier on TDA chip

    Now you should think about how to correctly connect a car amplifier. Everything is simple here. Assemble the power supply yourself (diagram below) and connect it to the on-board network. More on this later.

    5 Connecting and setting up homemade and factory audio devices

    Let's figure out how to connect a car amplifier yourself. If you have never done this kind of work, it is recommended to purchase a special set of electrical wires designed specifically for this purpose. A ready-made kit will allow you to quickly connect an amplifier (made yourself or factory-made). True, the sound quality in this case may not be the best. You can achieve ideal sound by using separate stranded copper wires:

    • 2x4 for subwoofer;
    • 2x1.5 for tweeters;
    • 2x2.5 for rear and front speakers.

    Any wire can be used as power wiring. It is usually connected to the car body with a minus, and to the power output of the radio - with a plus. But car audio professionals recommend connecting the amplifier a little differently - directly to the vehicle’s battery. In this case, you will have to spend money on a more expensive and thick wire KG-35 or KG-25. It must be connected to the existing terminals on the battery. The remaining wires (between the speakers and individual sides of the audio system) are also connected to terminals and special outputs.

    Setting up a car amplifier yourself, as a rule, does not cause serious problems. This operation should be performed strictly according to the instructions included with the factory sound amplification device. And homemade “gadgets” are adjusted using sound balance and volume controls, which, as noted above, are mounted in semiconductor and tube amplifiers.

    X Do you still think that diagnosing a car is difficult?

    If you are reading these lines, it means you have an interest in doing something yourself in the car and really save money, because you already know that:

    • Service stations charge a lot of money for simple computer diagnostics
    • To find out the error you need to go to specialists
    • The services use simple impact wrenches, but you can’t find a good specialist

    And of course you are tired of throwing money down the drain, and driving around the service station all the time is out of the question, then you need a simple CAR SCANNER ROADGID S6 Pro, which connects to any car and through a regular smartphone you will always find the problem, turn off CHECK and good save money!!!

    We tested this scanner ourselves on different machines and he showed excellent results, now we recommend him to EVERYONE! To prevent you from falling for a Chinese counterfeit, we publish here a link to the official website of Autoscanner.

    When I found on Ebay a tiny amplifier “PAM8610 stereo mini class D digital power amplifier board 2 x15W”, measuring 2.5 * 3 cm and costing about 350 rubles, I realized that I simply could not pass by.

    It turned out that 2*15W is the only option for 4 Ohm speakers. I didn’t have any of these, so I connected 2 * 10W with a reading of 6 ohms.

    Class D amplifiers get a lot of negative reviews from “serious” music lovers, but to my ears everything sounded just fine (and loud!), especially with decent speakers and an MP3 player with a built-in graphic equalizer and various additional settings.

    Using an MP3 player also means that there is no need to control the lows, highs and mids through a homemade sound amplifier; all you need is a volume control knob.

    Due to the fact that the wiring between the components is very simple, even novice hobbyists can easily assemble this project with their own hands.

    Step 1: Let's collect the necessary components

    To create an amplifier we will need:

    • 1 pc * plastic box. Mine was approximately 8 * 5 * 2.2 cm in size
    • 1 pc * PAM8610 Digital Power Amplifier Board 2 x 15w
    • 1 piece * 50K + 50K Dual Potentiometer
    • 1 piece * Double potentiometer button - choose the color to suit your taste.
    • 1 pc * SPDT (Single Pole - Double Throw) switch
    • 1 pc * 3.5 mm stereo jack socket for installation on the case
    • 1 piece * Power jack socket for installation on the case
    • 2 pcs * 10uF 25V electrolytic capacitors - the smaller the better
    • 2 pcs * 2-terminal or 1 pc * 4-terminal blocking screw terminals
    • 1 piece * 3mm LED (any color you like)
    • 1 pc * 4.7K 1/8W resistor (current limiting for LEDs - more details in the appendix)
    • 1 piece * 12V 2A AC adapter (more details in the app)
    • 1 piece * diode 1N5401 or 1N5822 (optional)

    In addition, to connect the components you will need a multi-colored stranded (7-core) wire.

    I have attached a PDF with a very detailed explanation of each item on the list. I wrote this document mainly for beginners, so if you just want a list of components, then skip most of the document and read only about the AC Adapter - this is very important.

    Files

    Step 2: Required Equipment

    This project keeps the amount of mechanical work to a minimum, so you only need three basic tools. Tools needed for drilling holes and soldering:

    1. Hand drill with a 1mm bit for drilling holes.
    2. Large drill for enlarging holes.
    3. Reamer drill.
    4. Soldering iron 18W - 25W.

    The reamer is my favorite tool for making holes in plastic and metal, and I recommend everyone keep one in their toolbox at all times. After making a 3mm hole in the center of the area where the desired component will be located, you take the drill and slowly press it in, turning it clockwise. After every few turns, you check that the component fits into the hole and is firmly seated.

    Soldering iron. There is nothing new to say about this tool that has not already been described in hundreds of other articles. All you need to know: practice makes perfect. You will be working with a circuit board that has chips mounted on its surface, so be very careful. Avoid splashing solder - one drop can ruin the entire amplifier.

    Step 3: Prepare the body




    In this step we will prepare the box for installing all the necessary components into it.

    Apply clean white tape to the surface of the cabinet where you will be mounting the switches and controls. In my case, I decided to make the front and back panels like real amps and marked where each component would be (see photo).

    The sticker allows you to mark the location of all control components and at the same time protects the surface of the case from scratches while you are drilling holes, etc.

    Using a 1mm mini drill, drill pilot holes along the marks you made earlier. Next, use a drill to widen the holes by 3mm (excluding the holes for the speaker connectors). Then widen the holes with a drill (following the tips from the previous part of the instructions). Do not widen the LED hole by 3mm unless you intend to use a larger diameter diode.

    You can see the results of the work in the attached photographs - neat holes that do not require further processing.

    You will notice that all the components are already screwed to the case, with the exception of the speaker terminals, these are threaded through the 1mm holes and glued to the case with superglue. The LED simply sits tightly in the hole, but it can be additionally secured with superglue.

    Step 4: Connecting the Components


    Wiring is very simple. For easy debugging, if something suddenly doesn’t work, I recommend using wires of different colors. For example, red is for positive wires, black is for negative or ground wires, orange is for all right channels, and blue is for left channels. To connect the speakers I used orange for right +, white for right -, blue for left +, brown for left -. You can use your own combination of colors, but try to use the same colors for the left and right channels.

    There are just a couple of simple things you need to know about polarity, read the attached PDF to become familiar with this information.

    Also take into account that I'm installing everything into a case using it as the top of my amp and the case cover being the bottom. This means that I am working with a mirrored assembly diagram. In real life, all components installed on the left will be on the right and vice versa. Be careful when connecting the speaker wires, if your layout is like mine the left speaker connections will be on the right and the right speaker connections will be on the left. This way, when you flip the amp case over, everything will fall into place.

    By looking at the attached photo you can see how easily everything fits together.

    Files

    Step 5: Troubleshooting and Precautions After Assembly

    After you've soldered everything together and before you connect the speakers and turn on the amplifier, you need to do some preliminary tests.

    Double-check that the components are connected correctly, or better yet, have a friend do it and make sure everything is connected correctly. A fresh look at the project will help you see what you might not notice after spending hours at home working.

    Using a multimeter, at low resistance ranges, check the circuit for short circuits at points 1, 3, 4, 5 and 6:

    • If you have a short at point 1, then your power adapter will explode as soon as you plug it into the outlet.
    • If you have a short between the speaker pins or between any pins on points 3 or 4 and ground, your amplifier module will explode. The right and left negatives are not common points, so under no circumstances short them together or connect them to ground.
    • If there is a short between the left or right channel and ground at point 5, then one of the channels may not work when turned on.
    • If the short is at point 6, then your power adapter will explode as soon as you turn on the switch on the case.

    Regarding the power switch (point 2), if you expect it to be on in the "Down" position and off in the "Up" position, set the switch to the "Down" position and using your ohm-range multimeter, measure the resistance between the two points rations. If you get anything other than zero ohms, the switch is flipped. Loosen the mounting screw and flip the switch 180 degrees until it is in the Up position. Switch it to the down position and check the resistance again. If it is still not zero, then your switch is most likely faulty.

    Additional protection. As noted earlier, you can damage the AC adapter if you use the opposite polarity to what your amplifier's wiring is designed for. You can protect yourself by adding one diode in series to the positive connection of the board. The connection diagram is shown in the attached diagram.

    In this case, if you connect the adapter with reverse polarity and turn on the device, the diode will not allow voltage to reach the amplifier module. In this case, the LED will also not light up - this will be an indicator to you that the polarity of the adapter is incorrect or the adapter itself is defective.

    The only drawback of such protection is that after the current passes through the diode, there will be a slight voltage drop, which is very important if your adapter produces exactly 12V.

    I recommend taking both 3A diodes. The difference is the forward voltage drop. If you use a standard 1N5401 rectifier, the voltage drop is about 0.7V, so the available voltage will be 11.3V or less. When using the Schottky Barrier Rectifier 1N5822 the drop is only 0.4V at 2A, so you will have at least 11.7V (which is closer to 12V). Choose one of these diodes depending on your needs. For example, if your AC adapter's current output voltage is 13V (which is entirely possible), then a 0.7V drop shouldn't matter, so you can use the 1N5401.

    MAXIMUM DEVICE VOLTAGE: The maximum voltage that the amplifier module can handle is 16V. To avoid damaging it, before connecting, check the actual output voltage of your AC adapter with a multimeter and make sure that it is significantly lower than 16V.

    Step 6: Turn on the device

    Once you have checked that everything is soldered well and that there are no shorts in the circuit (and also soldered the recommended diodes), you can connect the AC adapter, speakers (pull the entire exposed section of the wire all the way through so that the insulation reaches the clamp) and the MP3 player, lift a little volume level and turn on music. Enjoy the sound.

    If you didn't use a diode for protection, there is one more precaution you can take before turning on the power. Keep the +12V wire that goes to the amplifier module disconnected, connect the AC adapter, turn on the power and use a multimeter in the DC range, connect the red end to the disconnected red wire, and the black end to any black connection (ground), check that The voltage reading is positive in the range of about 12V.

    Once you are sure that the voltage and polarity are correct, turn off the device, unplug the adapter, solder the red +12V wire to the amplifier module and turn everything on following the instructions above. You are already on the way to good sound!

    Step 7: Conclusions

    When I started working on the instructions, I wanted to make everything simple and quick so that every beginner would understand how easy it is to create an inexpensive and small stereo amplifier. As I wrote the article, more and more nuances appeared that I would like to describe in more detail. Instead of pasting all this into the main text, I made a couple of PDFs and attached them to the necessary steps. I hope I haven't crossed the line between informative and boring.

    If you are new to electronics and you are going to build your own amplifier, then you should have at least the basic tools such as a soldering iron, solder, multimeter, screwdriver, pliers and wire cutters. Please also read all attached PDF files before starting.

    Much of the information is based on my many years of experience in the appliance repair business as well as training technicians for these tasks. It was very difficult for me not to mention all the nuances described, especially due to the fact that most authors do not delve into these problems. For me, this is the difference between the success or failure of a project.

    Hope you enjoy everything!

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