Preamp Circuit audio preamplifier IC LM358 dual op amp, LM358 Low Power Dual Operational Amplifiers General Description
The LM358 series consists of two independent, high gain, internally frequency compensated operational amplifiers which were designed specifically to operate from a single
power supply over a wide range of voltages. Operation from split power supplies is also possible and the low power supply current drain is independent of the magnitude of the power supply voltage.
Application areas include transducer amplifiers, dc gain blocks and all the conventional op amp circuits which now can be more easily implemented in single power supply systems. For example, the LM358 series can be directly operated off of the standard +5V power supply voltage which is used in digital systems and will easily provide the required interface electronics without requiring the additional ±15V power supplies.

Unique Characteristics

• In the linear mode, the input common-mode voltage range includes ground and the output voltage can also swing to ground, even though operated from only a single power supply voltage.
• The unity gain cross frequency is temperature compensated.
• The input bias current is also temperature compensated.

Features Lm686 opamp

•  Available in 8-Bump micro SMD chip sized package
•  Internally frequency compensated for unity gain
• Large dc voltage gain: 100 dB
• Wide bandwidth (unity gain): 1 MHz (temperature compensated)
• Wide power supply range: Single supply: 3V to 32V or dual supplies: ±1.5V to ±16V
• Very low supply current drain (500 µA) — essentially independent of supply voltage
• Low input offset voltage: 2 mV
• Input common-mode voltage range includes ground
• Differential input voltage range equal to the power supply voltage
• Large output voltage swing

This circuit can be used in various situations where it is necessary to amplify the audio signal of low intensity, for example: How a microphone preamplifier. This present version is mono but if you need to mount a stereo just use two equal units.

When mounting the preamp check all connections and components if everything is correct, connect the circuit to a battery source or in the range 9 to 20 Volts … Apply an input signal that can be for example a microphone and then adjust the 220K trimpot until the signal level suitable for your application … The adjuster will adjust the signal from 0 to maximum volume. To make connections to the input signal and the power amplifier to use shielded cables to avoid noise.

New PCB 2021 edition, corrected. Added R6 100K and Gerber Files.

Schematic of the audio preamplifier integrated circuit LM358 dual op amp

Suggested PCB mount preamp

 List of material for assembly of the pre-audio amplifier IC LM358

*for the power supply is 12 to 16 Volts.

Download the PDF to mount preamp: Datasheet LM158, LM258, LM358, LM2904, scheme, suggestion printed circuit board (PCB), the side covers, side components, Silk-screen.

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