This low-frequency (LF) stereo amplifier circuit on the TDA2005, which is easy to assemble and configure, can be used as an additional module in a car, or serve as a replacement for a burnt-out power amplifier in various audio equipment, or after supplementing it with a pre-amplifier circuit with tone control and balance, can become a full-fledged audio bass amplifier.
LF amplifier on TDA2005 - design description
It is based on the TDA2005 integrated circuit, which has two independent outputs in its structure. The circuit is quite simple, so it won’t be too difficult to assemble it yourself.
The circuit operates in standard connection. The degree of bass amplification of each of the individual channels is determined by the resistance of resistors R3 and R5, which can be changed in the range from 10 to 47 Ohms. To remove heat, the TDA2005 integrated circuit must be installed on a radiator with an area of at least 20 square meters. see. The radiator then needs to be connected to the common wire of the circuit.
Technical characteristics of the TDA2005 amplifier
- Supply voltage: from 8V to 18V;
- Maximum current consumption: 3.5 A;
- Output power: RL=4 Ohm - 20 W;
- Bandwidth (at -3 dB level): 40…20000 Hz;
- Quiescent current - 50 mA.
Bass amplifier assembly
Assembling the low-frequency amplifier circuit is quite simple and not particularly difficult. The parts are mounted on a board made of one-sided foil fiberglass. It is written in detail how to make it with your own hands. First, resistors and capacitors are soldered, paying attention to the correct polarity and the serviceability of the capacitors, which are desirable.
The TDA2005 chip must first be attached to the heatsink and then installed on the board. After carefully checking the installation and the absence of errors, we connect the speakers to 12 V. Next, you need to measure the current consumption. At rest it should be at 60 mA. A power source with a voltage of 12 - 15V and with a load current of more than 1.5 A. The capacitor in the power supply filter must have a capacity of at least 4700 µF.
The TDA2005 microcircuit has two inputs, as well as two outputs, which makes it possible to assemble a stereo amplifier based on it, which can operate at a load of 2 Ohms or more. A stereo amplifier, given its low output power, can be used when designing speakers for a personal computer.
Main characteristicsTDA2005
Supply voltage from 8V to 18V;
Output power (4 ohm load) per channel 6.5W;
Peak output current 3.5A;
The range of amplified frequencies is from 40Hz to 20kHz.
More detailed characteristics can be found in.
The TDA2005 chip has two switching circuits, for two outputs (stereo) and for one output (bridge circuit). I’ll tell you about the first connection circuit, that is, about a stereo amplifier.
TDA2005 electrical circuit diagram:
Electrolytic capacitors with a capacity of 2.2 μF 16V are used as C1 and C2. Capacitors C8 and C12 are ceramic; if you don’t mind, you can use film capacitors. Capacitor C5 is ceramic, soldered on the back of the board between pin 9 and ground. All other electrolytic capacitors should be rated at 16V if the amplifier supply voltage does not exceed 12V DC, otherwise use electrolytes at 25V.
All resistors indicated in the diagram must have a power of 0.25 W or more (if not 0.25 W).
According to the datasheet, resistors R3 and R6 should have a value of 3.3 Ohms, I set them to 30 Ohms, it works fine. In most circuits on the network, these resistors are installed with a nominal value of 33 Ohms.
The second version of the printed circuit board differs in its layout (there is a common point), and also in the fact that film capacitors are used as C1, C2, C8, C12, but this does not affect the sound quality of such an amplifier. Ceramic capacitor C5 is also soldered to the pins of the microcircuit on the back side of the printed circuit board.
TDA2005
This design can be made as an independent set of active speaker systems for reproducing a 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 microcircuit 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 within a wide range (by selecting resistor resistances in the OOS circuit). All this allows you to build a wide variety of amplifiers or active speaker systems based on the TDA2005.
Figure 1 shows a diagram of a simple set of active speakers with the following parameters:
1. Output power at THD = 10%, into a 4 Ohm load...........2 x 8W.
2. Output power at THD = 0.3%, into a 4 Ohm load...........2 x 5 W.
3. Input signal level to obtain an output power of 1 W. . 90 mV.
4. Gain factor taking into account losses in the tone control........36 dB.
5. Possibility of increasing the gain up to.........50 dB.
The circuit is powered from the power supply of an old HP840 printer (output voltage 18V), but the supply voltage can be from 8 to 18V, and the output power changes accordingly.
The stereo input signal goes to connector X1. A passive adjustment block is made on variable resistors R3, R5, R9. Double resistor R3 adjusts the HF tone simultaneously in both channels. Double resistor R5 is used to adjust the volume. Resistor R5 is used with taps from the “horseshoe”, which serve for loudness compensation, which improves the sound when operating at low volumes. Single variable resistor R9 serves as a stereo balance regulator.
The amplifiers included in the TDA2005 are powerful operational amplifiers with single-polar power supply, direct inputs - pins 5 and 1, inverse inputs, respectively, - pins 4 and 2.
By changing the resistance of resistors R13 and R15 (or R12 and R14), you can change the transmission coefficient of the amplification channels over a wide range. For resistances R13 and R15 the dependence 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 surge current 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 operate without them, in this case C13 and C16 are removed, and pins 7 and 11 are connected to the positive power bus (with pin 9). But in this case the maximum power is lower.
The parts of the adjustment unit are mounted directly on the terminals of variable resistors installed on the front panel of the housing of the main active speaker system in which speaker B2 is located. Since the regulators are passive, it is more convenient in all respects.
The parts 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.
Output capacitors C21 and C18, as well as smoothing capacitor C19, are located outside the printed circuit board (rigidly secured with clamps in the main speaker housing).
The printed circuit board does not have its own fastening elements - it is attached to the radiator using the radiator plate of the microcircuit, with one screw. The board together with the radiator is located in the housing of the main active speaker.
Only speaker B1 is located in the body of the second speaker. It is connected to the speaker base using a cable via 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 constructing 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 (you get two corners). Next, two corners are folded “over the roof” and placed in the middle inside a whole piece of profile. All mating surfaces must be coated with heat-conducting paste.
Satisfied after assembly, the decision came to build a stereo amplifier on the same chip.
Let’s immediately list the characteristics that the manufacturer claims:
- Supply voltage (V)……………………………………………………6-18
- Peak output current (A)……………………………3
- Quiescent current (mA)…………………………………………..75
- Reproducible frequency range (Hz)………………..40-20000
- Harmonic distortion factor (%)……………………….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
TDA 2005 amplifier with good characteristics.
In addition, you need to take into account its useful qualities:
- load short circuit protection;
- overheat protection;
- protection against power surges in the range up to 40 V;
- the amplifier has a wide range of supply voltages from 6 to 18 V.
The printed circuit board from 2005 was made in lay. Built taking into account the use of convenient terminal blocks.
One of the methods to reduce interference would be to connect the microcircuit housing to the minus of the general power supply.
- It is advisable to purchase capacitors 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
This car amplifier circuit based on TDA2005 has a number of advantages:
- speed of production;
- obtaining quite decent equipment;
- low cost of production.
At the output we get an amplifier measuring 70mm x 41mm:
Sound quality is acceptable. Pop and metal are played well. The bass doesn't mix into mush.
Now let's move on to the most interesting part, testing.
I’ll note right away that the circuit and printed circuit board on which the amplifier is assembled were taken from the Internet and are positioned as the most popular. Let's get started.
The amplifier was tested on Soviet speakers with an impedance of 4 Ohms. Transformer power supply 18 volts.
In terms of power supply: the amplifier starts working at 3 volts, although not very well, it choke at low frequencies. Already at a voltage of 19 volts the protection is triggered. Optimal power supply is 14 volts 3 amps.
The microcircuit gets very hot, so make sure you have a good heatsink, and it’s a good idea to use thermal paste.
Amplifier output impedance: oddly enough, but the readings are 0 Ohm.
The frequency response surprised me, it’s quite straightforward
Now let's connect it to the generator and see what happens.
1. The manufacturer promises a range of 40Hz-20kHz
I decided to run a sine wave at 10 Hz and the amplifier coped with it, albeit with distortion
Copes with a frequency of 100Hz without problems
At 1 kHz the booknife decreased noticeably
Well, at 10 kHz something terrible and incomprehensible is happening
As you can see, high frequencies are not his thing; the amplifier cannot cope with them. At 20 kHz the sinusoid ceases to be a sinusoid at all.
Now let’s send a 1 kHz square wave signal to the subject
On the graph we see a strong ringing, excitation at the peaks of the HF signal.
What we have in the end is ULF for 2005.
The amplifier itself is not bad. Low cost, simple element base, easy repeatability make this amplifier “people's”. You can’t blame him, since he didn’t claim a place among Hi-Fi amplifiers.
In addition, its simplicity allows it to be used for any application. Even in a simple computer speaker, or even built into a scooter or boat.
All the best!
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21.09.2014
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