electronics-amplifier tutorial

This is a 2 x 70W audio power amplifier circuit which built using single IC STA550. The amplifier circuit require few external components (most of them are resistors and capacitors) and is very easy to design The STA550 audio amplifier is capable to provide a maximum output power of 70 watts on two channels (70 + 70 watts).

This power amplifier circuit require a multi voltage power supply , because the amplifier require : +Vs Positive supply voltage referred to pin 13 (GND), Negative supply voltage referred to pin 13 (GND) -Vs, VCD+ Positive supply voltage tracking rail, VCD- Negative supply voltage tracking rail . The +Vs Positive supply voltage can be : +20 to +30 volts, -Vs Negative supply voltage : -10 to -22 volts , Positive supply voltage tracking rail VCD+ : +3 to 17 volts , Negative supply voltage tracking rail VCD- : -17 to -3 volts . VCD- must not be more negative than -Vs and VCD+ must not be more positive than +VS .

In this circuit diagram, R1/R3 (or R2/R4) ratio fix the gain of the preamplifier. If the input signal is very low, is possible to increase the gain fixing the product Vin*G = cost. In that case is possible to increase G decreasing R1,2 from 10KW until 2KW without relevant effetcs on the circuit behavior and remaining in the operating range Iin_max = Vin_max/R1(2) <1ma.>This is a 2 x 70W audio power amplifier circuit which built using single IC STA550.