Phonographs: A Fading Tradition
Phonographs are slowly fading into obscurity, making way for more advanced technologies like CD players, recorders, and portable MiniDisc player/recorders. This shift is acknowledged by audio installation manufacturers. Resulting in the omission of traditional phono inputs from a growing number of systems. Hi-fi enthusiasts aiming to digitize their vinyl collections face a challenge, as connecting a phonograph to these modern systems has become increasingly impossible.
Adapting Modern Amplifiers for Phonographs
With a relatively modest amount of circuitry, it is feasible to modify the line input of a contemporary amplifier or recorder to handle the low-level signals generated by the magneto dynamic cartridge of a phonograph. Essential to this circuit is the incorporation of the well-known RIAA correction, which is necessary for these cartridges. The preamplifier demonstrated here efficiently accomplishes this task using just one opamp, four resistors, and four capacitors. For a stereo setup, two of each component are naturally required. Any stabilized power supply capable of delivering ±15 V can serve as the power source.
Understanding Operational Amplifiers
An operational amplifier, commonly referred to as an op-amp, functions as a DC-coupled high-gain electronic voltage amplifier with a differential input and typically a single-ended output. In this setup, the op-amp generates an output potential that is typically 100,000 times greater than the potential difference between its input terminals.
Versatile Applications of Op-Amps
Op-amps serve diverse roles, primarily functioning as voltage amplifiers, which can be broadly categorized as noninverting and inverting amplifiers. Voltage followers, also known as buffers, are a commonly employed type of noninverting amplifier. Op-amps are also employed as differential amplifiers, integrator circuits, and more. An operational amplifier typically features two input pins and one output pin, with its primary function being the amplification and output of the voltage difference between the two input pins.
Electronic Amplifiers vs. Mechanical Amplifiers
Amplifiers can be classified as either electronic or mechanical, but operational amplifiers exclusively belong to the realm of electronic amplifiers. While amplifiers in general have limitations in amplifying DC signals, operational amplifiers are capable of effectively amplifying DC signals.