Definition
An electronic amplifier designed to increase the strength of a direct-current signal, or of a slowly varying signal whose frequency extends down to zero hertz. Unlike an AC amplifier, a DC amplifier is directly coupled between stages so that steady (non-alternating) voltages and currents pass through and are amplified along with any changes in the signal.
Plain English
A circuit that boosts a steady or slowly changing electrical signal so it is large enough to drive a meter, indicator, or control system.
Context Anchor
Seen in aircraft electrical, instrument, sensor, and automatic control system discussions, especially in maintenance or systems descriptions.
Derivation
‘Amplifier’ comes from the Latin amplificare, meaning ‘to make larger.’ ‘DC’ stands for direct current — current that flows in one direction only, as opposed to alternating current (AC), which reverses direction many times per second. So a DC amplifier is literally a ‘direct-current enlarger.’
Why Pilots Care
Ensures sensor signals reach cockpit displays and autopilot computers without loss of accuracy or drift.
Analogy
A DC amplifier is like turning up the volume on a quiet steady tone, except it is increasing an electrical signal instead of sound.
Intuition Check
A DC amplifier is not simply an amplifier powered by the aircraft battery. It is an amplifier designed to increase a direct-current signal.
Example Sentence 1
The autopilot's pitch channel uses a DC amplifier to boost the small signal from the rate gyro before it reaches the elevator servo.
Example Sentence 2
A DC amplifier boosted the steady voltage from the fuel quantity sensor before it reached the gauge.