Definition
A branch of electronics in which signals are represented by continuously variable voltages or currents that change smoothly over a range of values, directly mirroring the physical quantity being measured (such as pressure, temperature, or position).
Plain English
Electronics that use signals which rise and fall smoothly across any value, rather than switching between fixed on/off states. The signal looks like a continuous wave that copies the real-world thing it is measuring.
Context Anchor
Seen in aircraft maintenance when working with instruments, sensors, radios, control circuits, and older or mixed analog-digital systems.
Derivation
Analog comes from the Greek 'analogos,' meaning 'proportionate' or 'corresponding.' That fits the meaning here: the electrical signal is proportionate to — a direct copy of — the real-world quantity it represents.
Why Pilots Care
Many legacy aircraft instruments and sensor systems still rely on analog circuits, so maintenance personnel must understand them to diagnose and repair accurately.
Analogy
Think of a dimmer switch on a light: it can sit at any brightness between off and full. That is analog. A regular on/off switch is digital — only two states.
Intuition Check
Analog does not just mean “old” or “non-computer.” It means the electrical signal changes smoothly and continuously to represent a changing condition.
Example Sentence 1
The fuel quantity gauge in the older trainer uses analog electronics, with a voltage that varies smoothly as the float moves up and down inside the tank.
Example Sentence 2
Older airspeed indicators depend on analog electronics to translate pitot pressure into smooth needle movement on the dial.