A lot of electronic circuits in the domain of audio amplifiers are
already been published here. This circuit is a little different because
it is a four channel amplifier. Each channel of this amplifier can
deliver an output of 15Watts into a 4 ohm speaker. The amplifier can be
operated from a single 12V DC supply and this makes it possible to use
this amplifier in car audio applications too.
Circuit diagram :
4 X 15 Watt Mini Power Amplifier
The
circuit is based on the 15W BTL X 2 channel audio power amplifier IC
TA8215 from Toshiba. Even though chip is specifically designed for car
audio applications it can be also used for home audio applications. Two
TA8215 ICs are used here in order to obtain a 4 channel amplifier
system. The circuit is designed almost exactly as per the application
diagram in the ICs datasheet. Pins 7 and 19 are the Vcc pins of the ICs
internal integrated power amplifier stages and these pins are connected
to the positive supply. Pin 9 is the Vcc pin for ICs internal
preamplifier and it is also connected to the positive supply. Pins 13
and 14 are the internal power amplifiers ground pins and they are tied
together and connected to the ground.
The internal
preamplifier’s ground pin (pin5) is connected to the common ground
through a 10 Ohm resistor which makes the input ground separated from
the common ground by a resistance of 10 ohms and this improves the noise
rejection. The 100uF capacitor works as a power supply de-coupler. The
resistor networks connected to the output lines of each amplifier
improves the high frequency stability. The variable resistors (R3, R4,
R12 and R13) works as the volume controller for the corresponding
channels.
Notes :
- Assembling the circuit on a good quality PCB is a must for obtaining optimum sound quality.
- Use 12V DC for powering the circuit.
- The ICs must be fitted with adequately sized heat sinks.
- R3, R4, R12 and R13 serves as volume controllers.
- K1 to K4 can be 4 Ohm, 20W speakers.
- This amplifier circuit can be used in a variety of applications such as car audio systems, home theater systems, personal audio systems, public address systems etc. link
