Editing Pro Electron (section)

===The second letter denotes the intended use===

{|class="wikitable"
|-
! 2nd letter !! Usage  !! Example
|-
|A||Low-power/small-signal diode || AA119, BA121
|-
|B||[[Varicap|Varicap diode]] ||BB105G
|-
|C||Small signal transistor, R<sub>thJC</sub>&nbsp;>&nbsp;15K/W || BC546C
|-
|D||High-power, low-frequency power transistor, R<sub>thJC</sub>&nbsp;≤&nbsp;15K/W || BD139
|-
|E||[[Tunnel diode|Tunnel (Esaki-)diode]] || AE100
|-
|F||Low-power, [[Radio Frequency|RF]] (high-frequency) [[BJT|bipolar]] or [[FET]], R<sub>thJC</sub>&nbsp;>&nbsp;15K/W || BF245
|-
|G||[[Hybrid integrated circuit|Hybrid device]] || BGY32, BGY585
|-
|H||[[Hall effect sensor]]/diode ||
|-
|L||High-frequency, high-power transistor (for transmitters), R<sub>thJC</sub>&nbsp;≤&nbsp;15K/W || BLW34
|-
|M||[[Ring modulation|Ring modulator]]-type [[frequency mixer]] ||
|-
|N||[[Opto-isolator]] || CNY17 
|-
|P||Radiation detector ([[photodiode]], [[phototransistor]])|| BPW34
|-
|Q||Radiation generator ([[Light-emitting diode|LED]])|| CQY99 
|-
|R||Low-power control or switching device: [[thyristor]]s, [[diac]]s, [[TRIAC|triac]]s, [[Unijunction transistor|UJT]]s, programmable unijunction transistors (PUT), silicon bidirectional switch (SBS), opto-triacs etc. || BR100 
|-
|S||Low-power switching transistor, bipolar or [[MOSFET]], R<sub>thJC</sub>&nbsp;>&nbsp;15K/W || BS170
|-
|T||High-power control or switching device: [[thyristor]]s, [[TRIAC]]s, silicon bidirectional switch (SBS), etc. || BT138 
|-
|U||High-power switching transistors, bipolar or [[MOSFET]], R<sub>thJC</sub>&nbsp;≤&nbsp;15K/W || BU508, BUZ11
|-
|V||[[Antenna (radio)|Antenna]] ||
|-
|W||[[Surface acoustic wave#Application in electronic components|Surface-acoustic-wave device]] ||
|-
|X||[[Frequency multiplier]]: [[varactor]], [[step recovery diode]] ||
|-
|Y||High-power rectifying diode || BY228 
|-
|Z||[[Avalanche diode|Avalanche]], [[Transient voltage suppressor|TVS]], [[Zener diode|Zener]] diode || BZY91 
|}