Audio amplifier circuit using lm386 with printed circuit board and Schematic
The LM386 is a power amplifier designed for use in low voltage consumer applications. The gain is internally set to 20 to keep external part count low, but the addition of an external resistor and capacitor between pins 1 and 8 will increase the gain to any value from 20 to 200.The inputs are ground referenced while the output automatically biases to one-half the supply voltage. The quiescent power drain is only 24 milliwatts when operating from a 6 volt supply, making the LM386 ideal for battery operation.
Features:
- Battery operation
- Minimum external parts
- Wide supply voltage range: 4V-12V or 5V-18V
- Low quiescent current drain: 4mA
- Voltage gains from 20 to 200
- Ground referenced input
- Self-centering output quiescent voltage
- Low distortion: 0.2% (AV = 20, VS = 6V, RL = 8[Ohm], PO = 125mW, f = 1kHz)
- Available in 8 pin MSOP package
Applications
- AM-FM radio amplifiers
- Portable tape player amplifiers
- Intercoms
- TV sound systems
- Line drivers
- Ultrasonic drivers
- Small servo drivers
- Power converters
Equivalent Schematic and Connection Diagrams LM386M-1, LM386MM-1, LM386N-1, LM386N-3 or LM386N-4
Application Hints
GAIN CONTROL
To make the LM386 a more versatile amplifier, two pins (1and 8) are provided for gain control. With pins 1 and 8 open the 1.35 kΩ resistor sets the gain at 20 (26 dB). If a capacitor is put from pin 1 to 8, bypassing the 1.35 kΩ resistor, the gain will go up to 200 (46 dB). If a resistor is placed in series with the capacitor, the gain can be set to any value from 20to 200. Gain control can also be done by capacitively coupling a resistor (or FET) from pin 1 to ground.Additional external components can be placed in parallel with the internal feedback resistors to tailor the gain and frequency response for individual applications. For example, we can compensate poor speaker bass response by frequency shaping the feedback path. This is done with a series RC from pin 1 to 5 (paralleling the internal 15kΩ resistor). For 6 dB effective bass boost: R. 15 kΩ, the lowest value for good stable operation is R = 10 kΩ if pin 8 is open. If pins1 and 8 are bypassed then R as low as 2kΩ can be used. This restriction is because the amplifier is only compensated for closed-loop gains greater than 9.
Schematic of power audio amplifier for applications as Amplifiers of radio FM, Amplifiers of mp3 portable players, Intercoms, Systems of sound of TV and other applications.
Schematic circuit amp using lm386
The power supply for this circuit should be 3 to 12 volts.
Suggestion of printed circuit board
Part List for the LM386 Amp
| Component | Value |
| Resistors 1/4W 5% | |
| R1 | 10 – Brown, Black, Black, Gold |
| R2 | 1.2k – Brown, Red, Red, Gold |
| R3 | 4.7K – Yellow, Violet, Red, Gold |
| R4 | 1.5K – Brown, Green, Red, Gold |
| Capacitors | |
| C1, C6 | 10µF/16V – Capacitor electrolytic |
| C2 | 220µF/16V – Capacitor electrolytic |
| C3 | 100n – Ceramic or polyester capacitor |
| C4 | 1000µF/16V – Capacitor electrolytic |
| C5 | 100n – Capacitor ceramic |
| Semiconductor | |
| IC1 | LM386 |
| LED1 | Red Led 5mm |
| Connectors | |
| J1 | P2 connector – audio input |
| J4 | Jack Connector – DC Power |
| J5 | Audio input connector (optional) |
| J6 | Power connector (Optional) |
| JP1 | Jumper gain adjustment (optional) |
| OUT | Terminal block connector 2 screws – Audio output |
| Miscellaneous | |
| P1 | Single potentiometer 4.7K |
| 3 to 12V / 1A power supply | |
| Printed circuit board, solder, wires, box, knob, etc. | |
Download PDF files for Lm386 amplifier
Download PDF Mirror
