There are many silk-screen letters on the PCB, such as R107, C118, Q102, D202, etc. Do you know what these letters mean? In fact, the letters on the PCB represent the abbreviations of electronic components, and there are often numbers behind the letters, and these numbers also have meanings.
The meaning of some letters on the PCB
B: buzzer
C: capacitor
D: diode
F: fuse
J: jumper
L: inductor
Q: transistor
R: resistor
RT: thermistor
T: transformer
U: chip, integrated circuit (IC)
W: voltage regulator
Y: crystal oscillator
R107, C118, Q102, D202 and other numbers are often seen on circuit boards. Generally, the first letter identifies the device category, such as R for resistor, C for capacitor, D for diode, Q for triode, etc.; the second is a number, indicating the circuit function number, such as "1" for the mainboard circuit, "2" for the power supply circuit, etc., which is determined by the circuit designer; the third and fourth digits indicate the serial number of the same type of device on the circuit board.
R117: resistor on the motherboard, serial number 17
T101: transformer on the motherboard
SW102: switch
LED101: light-emitting diode
LAMP: (indicator) lamp
Q104 (E, B, C): transistor, E: emitter, B: base, C: collector
