Saturday, March 8, 2008

Sound project to build an amplifier

Audio Amplifier Constructional Project
This audio amplifier project is a class AB audio power amplifier using a TDA2003 module power amplifier. It is easy to construct and has only a few external components. The module is designed with short circuit and thermal protection. It can drive loads as low as 1.6 ohm and is capable of delivering over 10 watts from a 16 V DC power supply. Figure 1 shows the TDA 2003 packaged and pin configuration.
The power supply required for is 8 - 18V DC at 1 Amp or more. Maximum output power will only be obtained with a power supply of greater than 1A at 16V DC, and using 2 ohm speakers (or 2 by 4 ohm speakers in parallel). However approximately 4W RMS can be obtained with a 12V DC, 1A supply into a 4 ohm load.
The power supply should be well filtered to reduce mains hum, the on board capacitors alone are not adequate for this purpose but are necessary to ensure stability. Extra filtering is unnecessary if operating from a battery. If two boards are used for stereo, you will need to double the size of the power supply.
Audio Amplifier Circuit Diagram

he major circuitry is contained in the amplifier module. C1 is the input coupling capacitor and blocks DC signal, so does C3 which is the output coupling capacitor, and C2 which blocks DC from the feed back loop to the differential input. R2 and R3 set the level of feed back. C4 and R4 provide a high frequency load for stability where loudspeaker inductive reactance may become excessive. C5 and C6 provide power supply decoupling or filtering.
There should be no problems with the stability of the circuit, however if you do, make sure the power supply filtering and leads are adequate. If necessary you might connect an RC compensation network between IC pins 2 and 4 as in the data sheet. Values for Cx of 22 - 33 nF and for Rx of 39 - 47 ohms, should be satisfactory whilst still maintaining satisfactory high frequency response.
The gain is equal to 1 + (R2/R3) = 101, or 40 dB, minus any input attenuation. You may reduce the overall gain by increasing the value of R3 if you are only able to use part of the potentiometer range as a volume control. For example, an R3 of 10 ohms will give a gain of 23 (27dB).
Parts List
The parts list of this project is as shown below.

TDA2003 data sheet can be downloaded from Audio Amplifier TDA2003 ST Website


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