Definition
A memory aid used to identify the emitter lead of a bipolar junction transistor. The first letter of each word -- C, C, L, T -- corresponds to the direction conventional current flows in the three transistor types: Conventional Current Leaves the Transistor at the emitter of a PNP transistor, and conventional current enters the transistor at the emitter of an NPN transistor (the reverse of CCLT). The phrase fixes which lead is the emitter and which way current is treated as flowing through it.
Plain English
It's a short sentence pilots and technicians use to remember how current flows through a PNP transistor. The first letters spell out the rule: in a PNP, the current flows out of the emitter; in an NPN, it flows in.
Context Anchor
Seen when reading aircraft electronics diagrams or studying how transistor symbols are used in electrical systems.
Why Pilots Care
Knowing the direction prevents mistakes when reading schematics or troubleshooting transistor circuits in aircraft power and radio systems.
Intuition Check
Do not read “conventional current” as the actual path of electrons. It is the standard positive-to-negative current direction used on circuit diagrams.
Example Sentence 1
When the instructor asked which lead was the emitter on the PNP transistor, the student remembered CCLT -- Conventional Current Leaves the Transistor -- and pointed to the correct pin.
Example Sentence 2
During preflight checks of the comm system, remember that conventional current leaves the transistor through the emitter leg.