Direct coupling audio power amplifier configuration A741 circuit
Posted on Nov 10, 2015 9752
As shown for the direct coupling audio power amplifier. When using an integrated operational amplifier
constituting the audio power amplifier, there are usually two practical forms.The first practical form as shown in (a), the structure of the circuit is in the output of op amp plus complementary symmetry emitter follower, this form of structure is simple, easy to use, but lower power utilization. Figure (a) know, shoot the circuit two transistors are connected in series pole resistance RE (1.2 ), whose role is to implement over-current amplifier transistor in the integrated operational amplifier output terminal (pin 6) External 1k resistor to A741 also play the role of overcurrent protection. Figure (a) in which the voltage amplification factor of about 101,4 diodes are 1S953, amplifier tube for the tube, model 2SC524 and 2SA524.The second practical form as shown in (b), the circuit is the use of the operational amplifier supply current excitation complementary symmetry common emitter amplifier, power output parameters as shown in the figure is about 2W. A741C power operational amplifier itself is small, the output stage of the two class AB amplifier tube operating in the enlarged state, the power consumption is also small, and thus a higher efficiency when taking a few milliamps of output current, supply current is substantially close to the load current. Positive and negative power terminal of the operational amplifier (pin 7,4), respectively, with the base of transistor Q1 and Q2 is connected to that supply current to become operational amplifier Q1 and Q2 base excitation current. Role Figure (b) of the resistor R3 (47 ) is to increase the power supply current, which increases both the power amplifier tube base excitation current. Resistor current limiting resistor R4, to A741C play the role of overcurrent protection.