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Recently a friend asked if I could build a compact car amplifier for him. The problem is that he was not at all satisfied with the volume of the Chinese-made speakers and the quality of their sound, which was already installed in the car. Nothing complicated, so why not!
After a little thought, I chose a well-known microcircuit as the base TDA2005 (TDA 2005). Many will ask what is good about it ?! Let me give you a little clarification on this:
- Firstly, a 12-volt unipolar source can serve as a power source for this microcircuit. That is why it is an excellent basis for the manufacture of a budget car amplifier.
- Secondly, TDA2005 among its "peers" is distinguished by higher quality and bandwidth from 30 Hz to 20 kHz, with a non-linear distortion coefficient (THD) of only 0.3%. This is truly a unique indicator, since most of these microcircuits have an THD of about 10%.
The assembly of the circuit was carried out by me in a hinged way, without the use of circuit boards, all the details were filled with heat-resistant glue at the end. The circuit I assembled received a stereo connection option, although when using a bridge circuit, this microcircuit could output about 24 watts at the output. This option is the best solution for a low power car subwoofer. The main advantage of this method is the absence of the need for voltage conversion.
The car amplifier I made is capable of delivering 12 watts per channel, the number of channels is two. The current strength without taking into account the input signal is about 70 mA. The efficiency of the microcircuit is not more than 70% (everything else is spent on heating), this is how it works in class AB. It follows that for the normal functioning of the TDA2005 chip, a cooling system is required.
A peculiar additional method of reducing interference is the connection of the microcircuit case to the minus of the general power supply, but through a separate wire.
When purchasing spare parts, choose the following items:
- it is advisable to purchase capacitors for 16 volts, and ideally for 25 volts;
- resistors, the best option is 0.25 watts;
- be sure to purchase input wires with shielding, this will protect you from additional interference and extraneous sounds (for example, high-frequency noise emitted by the power supply or on-board network, radio waves, etc.).
- manufacturing speed;
- obtaining quite decent equipment;
- cheapness of manufacture.
The amplifier on the TDA2005 chip is stereo ULF with an output power of 10-12 watts per channel, there is also a mono option, in this case the output power of the amplifier is 20-25 watts. ULF is powered by 12 volts, so this option is optimal for car amplifier small power. I want to say this right away, to remind you that winter is just around the corner and I want to recommend Yokohama iceGUARD tires. Find out all the advantages, go and order shinaland.com.ua/tyres/yokohama/iceguard-stud-ig35
This amplifier circuit has several advantages:
1. .Fast assembly
2. Components are cheap
3. High-quality and clear sound
The amplifier works in class AB and 30% of the efficiency of the microcircuit goes to heating, so additional cooling is required. You can attach the microcircuit through special gaskets and washers to the radiator. Since the TDA2005 gets quite hot, choose a large heatsink.
Technical characteristics of ULF on TDA2005
- Supply voltage (V)………………………………………………6-18
- Peak output current (A)……………………………….3
- Quiescent current (mA)………………………………………………………………………75
- Frequency response (Hz)……………….40-20000
- THD (%)…………………………1
- Nominal load resistance (Ohm)…………………..3.2
- Minimum load resistance (Ohm)……………………..2
- Output power (W at 18 V supply voltage)….22
- Input sensitivity (mV)…………………………………………300
- Gain (dB)………………………………………………..50
To reduce interference, you can connect the microcircuit case to the minus power supply with a separate wire. Choose capacitors with ratings of 16 - 25 volts. The sensitivity of the amplifier to low frequencies depends on the capacitance of the input capacitor. Resistors select 0.25 watts.
The circuit also has a noise suppression filter, it is assembled from 2 capacitors, an electrolyte and a choke. Capacitors are used to smooth out low-frequency noise, and a choke for high-frequency noise. This filter suppresses noise from the engine, which is sometimes heard from the speakers.
21.09.2014
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The role of a virtual resistor in the volume control is performed by 2 multiplexers D4 D5 and a set of resistors R6-R20. Multiplexers act as a 16-position switch. In this case, the adjustment law can be chosen by yourself by changing the ratings R6-R20. if you need a double resistor, then we take 2 more multiplexers with resistors and connect their control inputs (outputs ...
TDA7294 is an integrated circuit amplifier module. It is intended for use as a class AB audio amplifier in Hi-Fi audio equipment. TDA7294 has a wide range of output voltage and output current, which allowed TDA7294 to be used both in 4 ohm and 8 ohm loads. TDA7294 will give out 50W (RMS) on...
The KR174UN31 microcircuit is intended for use as an end stage for amplifying the audio signal supplied from the microcircuit directly to loudspeakers (resistance over 8 ohms), in small-sized equipment (radio receivers, players, cordless phones). The microcircuit parameters are presented in Table 1. The microcircuit is available in an 8-pin DIP package (type 2101.8-1). The drawing is given in Fig.1. Typical switching circuits - ...
TDA2005
This design can be made as an independent set of active speakers to reproduce the signal from the output of a personal computer, or used as a repair circuit for repairing a purchased active speaker with a faulty AF power amplifier circuit.
The TDA2005 chip belongs to the category of inexpensive and widely available integrated UMZCH. A relatively small number of attachments, combined with good electrical characteristics, the presence of output overload protection, thermal protection, as well as the ability to set the transmission coefficient over a wide range (by selecting the resistances of resistors in the environmental protection circuit). All this makes it possible to build a wide variety of amplifiers or active speaker systems on the basis of the TDA2005.
Figure 1 shows a diagram of a simple set of active speakers with the following parameters:
1. Output power at THD = 10%, at a load of 4 ohms ........... 2 x 8W.
2. Output power at THD = 0.3%, at a load of 4 ohms ........... 2 x 5 W.
3. Input signal level, to obtain an output power of 1 W. . 90mV.
4. Gain taking into account losses in the tone control ........ 36 dB.
5. Ability to increase the gain up to ........... 50 dB.
The circuit is powered by the power supply of an old HP840 printer (output voltage 18V), but the supply voltage can be from 8 to 18V, while the output power changes accordingly.
The input stereo signal is fed to connector X1. On the variable resistors R3, R5, R9, a passive adjustment block is made. The double resistor R3 controls the treble tone simultaneously in both channels. The double resistor R5 serves to adjust the volume. Resistor R5 is used with horseshoe taps, which are used for loudness compensation, which improves sound when working at low volume. A single variable resistor R9 serves as a stereo balance control.
The amplifiers included in the TDA2005 are powerful single-supply operational amplifiers, direct inputs - pins 5 and 1, inverse, respectively - pins 4 and 2.
By changing the resistances of the resistors R13 and R15 (or R12 and R14), it is possible to change the gain of the amplifying channels over a wide range. For resistances R13 and R15, the relationship is inverse, and for R12 and R14, it is direct.
The R10-C12 circuit is used to smoothly turn on the amplifiers, in order to avoid current surges in speaker systems.
Capacitors C13 and C16 create a voltage boost to the output stage, increasing the output power without increasing the supply voltage. The amplifier can work without them, in this case, C13 and C16 are removed, and pins 7 and 11 are connected to the positive power rail (with pin 9). But in this case, the maximum power is lower.
Details of the adjustment assembly are mounted directly on the terminals of variable resistors installed on the front panel of the main active acoustic system housing, in which speaker B2 is located. Since the regulators are passive, it is more convenient in every way.
The details of the amplifier itself are mounted on a small printed circuit board, the diagram of which is shown in Figure 2.
The board is made of single-sided foil glass-textile.
The output capacitors C21 and C18, as well as the smoothing capacitor C19, are located outside the printed circuit board (rigidly fixed with clamps in the main speaker case).
The printed circuit board does not have its own fasteners - it is attached to the radiator by means of the microcircuit radiator plate, with one screw. The board, together with the radiator, is located in the case of the main active speaker.
In the case of the second speaker, only speaker B1 is located. It connects to the speaker base with a cable through connector X2.
To remove heat from the microcircuit, a radiator is used, the design of which is shown in Figure 3. The radiator is made of a metal profile for the installation of a frame for suspended ceilings or plasterboard panels. For one radiator, you need to cut two pieces 10-15 cm long. Then, one of the pieces needs to be cut lengthwise into two identical parts (two corners will turn out). Further, two corners are folded “overlapping” and placed in the middle inside a whole piece of profile. All mating surfaces must be coated with heat-conducting paste.
Does not require adjustment. It only takes a little time to assemble and mount into a case if desired.
The technical characteristics of the amplifier on the TDA2005 are as follows:
- Supply voltage (V) - 6-18
- Peak output current (A) - 3
- Current at rest (mA) - 75
- Frequency response range (Hz) - 40-20000
- THD (%) - 1
- Nominal load resistance (Ohm) - 3.2
- Minimum load resistance (Ohm) - 2
- Output power (W at 18 V supply voltage) - 22
- Input sensitivity (mV) - 300
- Gain (db) - 50
In the article, I will offer you three board options for a mono amplifier and one option for a stereo amplifier.
This amplifier has proven itself excellently as simple, reliable and picky. It is most often built into homemade home guitar cabinets (i.e. suitable for guitarists), as well as low-power car radios (especially in the 90s). Don't let the phrase "low power" scare you - the gain of this microcircuit is enough to scare the neighbors. Just 20 watts for a car now is really nothing compared to kilowatt amplifiers and speakers, from which, when turned on at full power, eardrums can easily burst.
Let's start with the board, which, in my opinion, has the most successful ground wiring.
Here is the diagram, the board, the arrangement of parts on the board and the parameters of the amplifier parts on the TDA2005:
Simple mono amplifier board on TDA2005
Layout of parts on a simple mono amplifier on TDA2005
Parts list:
It was the version with this board that I built into my conversion of the Soviet S30 speaker into a guitar combo amplifier.
You don't need to mirror the payment.
After assembly it turned out like this:
Only in the photo is a very small radiator. For an amplifier on the TDA2005, you need more. Therefore, it was replaced with a larger radiator.
Now let's move on to the rest of the PCB layout options.
The second version of the mono amplifier board on TDA2005.
How to solder the volume control and signal wires:
The third version of the mono amplifier board on TDA2005.
Choose any option :) I liked the very first one more.
Now to the stereo amplifier on TDA2005.
His pay is a little more:
And the scheme is slightly different:
Let me remind you that the stereo amplifier on the TDA2005 develops half as much power as the mono amplifier. However, you can always build two mono amplifier boards and get stereo. Only power is needed with the same voltage, but the current strength is about 5-6 A.
It remains to show one more version of the mono amplifier circuit recommended by the manufacturer.
