Amplifier Circuit DiagramsAudio Circuit Diagrams

Low-Noise Microphone Amplifier Schematic Circuit Diagram

The microphone signal is too weak for a standard line input, but this low-noise DC-coupled microphone amplifier offers a solution for individuals looking to connect a microphone to their hi-fi setup. The circuit, as shown in the schematic diagram, proves that a reliable circuit doesn’t have to be overly complicated. It features a differential amplifier centered around T1 (MAT-03E), a low-noise dual transistor. T2 and LED D1 together create a constant-current source for the input stage.

Low-Noise Microphone Amplifier Schematic Circuit Diagram

A Quiet Amplifier for Precise Signal Processing

The OP-270E, a low-noise operational amplifier, efficiently amplifies the differential signal emerging from the dual transistor collectors. This operation results in an analog signal at line level, exhibiting a bandwidth spanning from 1 Hz to 20 kHz. Remarkably, within the audio range of 20 Hz to 20 kHz, distortion remains below 0.005 percent. Utilizing only half of the OP-270E allows the spare opamp to be utilized in the output stage for a stereo version. This versatile amplifier can be powered by a stabilized, symmetrical supply, ranging between ±12 V and ±15 V, voltages readily available in many existing amplifiers.

Op-Amps: Powerful Voltage Amplifiers with Multifaceted Applications

Operational amplifiers, commonly known as op-amps, stand as DC-coupled, high-gain electronic voltage amplifiers, boasting a differential input and usually a single-ended output. Operating in this setup, op-amps generate an output potential typically magnified by a factor of 100,000 in comparison to the voltage difference between their input terminals.

Diverse Functions of Operational Amplifiers

In their fundamental role, op-amps act as voltage amplifiers, falling into categories such as noninverting and inverting amplifiers. Noninverting amplifiers, often referred to as voltage followers or buffers, represent a widely used type of op-amp. Additionally, op-amps find application as differential amplifiers, integrator circuits, and more. The operational amplifier, an integrated circuit (IC), specializes in amplifying the voltage difference between two inputs. Its nomenclature derives from its capacity to perform arithmetic operations. To minimize noise, a common technique involves employing a feedback capacitor to limit the op-amp’s bandwidth. This limitation effectively reduces noise, making the feedback capacitor a prevalent method for noise reduction in op-amp circuits.


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