The module is based on the popular LM4766 chip, completed with a symmetrical power supply. The assembled plate is a ready-made functional block of the audio system. The circuit diagram is shown in circuit schematic. The U1 (LM4766) systems...Electronics Projects, LM4766 Amplifier Circuit Module "audio amplifier circuits, ic amplifier, " Date 2019/08/04
The module is based on the popular LM4766 chip, completed with a symmetrical power supply. The assembled plate is a ready-made functional block of the audio system. The circuit diagram is shown in circuit schematic. The U1 (LM4766) systems operate in a non-inverting configuration.
The input signal from the IN socket, through the C5 and C6 separating capacitors, is fed to the amplifier input. Resistors R3, R5, R4 and R6 close the feedback loop and set the amplification of the tip (sensitivity at 20W / 8OHM is about 1 Vrms). The RC (R1 / C1 and R2 / C2) circuits provide amplifier stability for inductive loads.
The system power supply is symmetrical and unstabilized, obtained from the BR1 KBL06 rectifier and the CE3, CE4 filter. The system, depending on the output power, is supplied from the 2×15 … 22 VAC 90VA transformer and the corresponding current efficiency.
The system is completed with an external muting circuit. Due to the reference to the negative pole of the VEE power supply, which is not very convenient for external control, the system has been supplemented with an IS optocoupler. Shorting the socket outlet ON, activates the amplifier.
LM4766 Amplifier Circuit Schematic
The system can be controlled by a relay or an OC type output, accepting a voltage of up to 35 V in the open state. If you do not need to mute the amplifier remotely, you can omit elements D1, R10, R11, IS, ON and short terminals 3-4 IS.
The amplifier was assembled on a double-sided PCB. The assembly is typical and does not require a description. Due to the power dissipated, U1 requires mounting on a heat sink with a suitable surface. Due to the connection of the radiator insert with the power supply, an insulating washer should be used and, of course, a thermally conductive paste. Of course, it is possible to use the insulated version LM4766TF and omit the insulation pad.
The method of switching on the amplifier. It is also possible to use the amplifier in the bridge version, for this purpose the signals of opposite phases should be led to the input, and the loudspeaker should be connected to pins 1, outputs OA, OB. This allows the amplifier to be used, for example, in the 2.1 system for powering the subwoofer and realizing the gain path on identical channel amplifiers.