100+100 Watt Stereo Amplifier PCB
Price Rs 199.00 each
100+100 Watt Stereo Amplifier Assembled Board
Price Rs 1399.00 each
100 + 100w stereo amplifier board solder side
This is a complete Stereo Amplifier in one board
You have to just add transformer and it is ready to go.
The Big Capacitor & Rectifier power supply on this board has a Dual DC output connector ,
So you can connect Subwoofer amplifier board and make a High power 2.1 system.
input can be given from USB / Bluetooth player or Mobile phone or any type of CD / DVD / PC / Laptop / LCD LED TV.
CLICK HERE to download 200w Stereo amplifier circuit diagram
Left Channel Working is described below, the other channel works the same.
Power Supply Section -
Power supply section consist of Bridge Rectifier D1 which rectifies AC coming from transformer, the rectifierd DC then filterd by Reservoir capacitors C19, C20, C21, C22.
DC output jack is provided to connect other amplifire boards for making multi channel Amps.
Input stage works as a transconductance amplifier (voltage in - current out).This stage consist of Long Tailed Pair (LTP) made of Q1 & Q2 working as differential amplifier.
Input signal received at the base of Q1 is amplified and sent to VAS from collector.
Negative feedback (NFB) received at the base of Q2 from output determines overall gain and balance of the amplifier. Current is supplied to the LTP by resistor R4.
Constant current source is made of Q18, R4,D3 which provided current to input pair.
In simple words input signal is amplified by the input pair Q1 & Q2 and sent to VAS for further amplification.
Voltage Amplification Stage (VAS)
As the name suggests, all the voltage gain of the amplifier is achieved in VA Stage.
Signal received from input stage at the base of Q3 is Voltage amplified and sent to the base of driver transistor Q5.Current is supplied to VAS by resistor R9 & R10.
Biasing circuit is made of transistor Q4, which works as voltage divider. With preset RV1, base current of output transistors can be precisely adjusted.
Important to note that the biasing transistor Q4 & driver transistor Q5 can be tied together for better thermal tracking.
In simple words signal received from input stage is amplified by Q3 & sent to output stage.
Output Stage ( OPS )This circuit has Class AB output stage, so each half of the signal is amplified by each NPN and PNP output transistors.
Driver Transistors Q5 & Q6 work as buffers to prevent excessive loading of VAS and also provide input to the output transistor Q7 and Q8 respectively.
Output Topology is Complementary Feedback pair which has improved linearity and better thermal tracking.
Zobel Network - made of R15 & C6, provides protection against high frequency oscillations.
In simple words signal received from VAS is given to the output transistors via driver transistors. Output transistors conduct high current to drive the speakers load.
* - Always use complementary NPN-PNP pairs.