Definition
An electronic filter circuit, typically built from capacitors and inductors, placed at the output of a rectifier to smooth out the small voltage fluctuations (ripple) that remain after alternating current has been converted to direct current.
Plain English
A circuit that cleans up the leftover bumps in a DC power supply so the output is a steady, smooth voltage instead of one that still wobbles.
Context Anchor
Seen in aircraft electrical system descriptions and troubleshooting, especially when discussing alternator output, power supplies, or radio noise.
Derivation
Ripple' comes from the visual idea of small waves on water — here it describes the small leftover waves of voltage on a DC line after rectification. 'Filter' simply means a device that removes something unwanted. Together: a device that removes the small voltage waves.
Why Pilots Care
Unfiltered ripple can cause erratic instrument readings, radio interference, or avionics malfunctions during flight.
Intuition Check
Ripple does not mean the airplane is shaking. Here it means small unwanted ups and downs in electrical voltage. Filter does not mean an air or oil filter. Here it means an electrical circuit that reduces an unwanted part of the power.
Example Sentence 1
The ripple filter in the power supply smooths the rectified output before it reaches the avionics bus.
Example Sentence 2
During the electrical system check, the ripple filter kept the DC bus voltage steady despite alternator output variations.