A handsome single chip 10 watt power amplifier can be built quite easily using the IC TDA2003 and a handful of other passive components. I had built this circuit quite a long time ago, but I still remember the outstanding response it produced with an input music applied to it from a Sony Walkman. The circuit is very straightforward and be constructed even by a newbie.
Before learning how to build your own power amplifier, let’s first discuss the circuit functioning. The circuit description of the unit may be understood by studying the following points:
Input to the IC is received at pin #1 through capacitor C1 and the output is delivered to the loudspeaker connected to its pin #4 through a relatively large value electrolytic capacitor C4.
The IC is able to produce a fairly good response even at high frequencies, but this also means that the connected loudspeaker will be offering proportionate rising impedance to these frequencies and lowering the net efficiency of the amplifier.
An RC network consisting of R3 and C5 has been specifically introduced to rectify the above problem. It compensates for the rising frequencies and cancels out the effect of the speaker’s rising impedance.
The circuit also incorporates a feedback loop consisting of R1 and R2 that is responsible for defining the overall amplification of the unit. Here it has been set to produce an amplification of about 100 times.
Resistors R4 and capacitor C7 ensures proper stability of the IC at high frequencies by avoiding any clipping effect.
Power to the IC is applied across its pin #5 and #3. The power range is also pretty flexible and allows the amplifier to function optimally even at voltages as low as 3 volts, 18 volts being the maximum tolerable limit. Voltages above this won’t necessarily damage the IC, but the internal circuitry of the IC is so configured that in such conditions the IC will stall and just “refuse" to operate. The robust design of the IC is reinforced by internal short circuit and thermal run away protections.
The IC should be preferably fitted with a heat sink, if it’s intended to be driven continuously at its full capacity i.e. 10 watts. Again, it may be required only to avoid the IC from shutting off due to overheating, and not due to the fear of the IC getting damaged.