Pro Electron

Designation system

Examples of Pro Electron type designators are:

AD162 – Germanium power transistor for audio frequency use

BY133 – Silicon rectifier

BZY88C5V1 – Silicon 5.1 volt Zener diode

CQY97 – light emitting diode

ECC83 – 6.3 volt heater noval dual triode

A63EAA00XX01 – Color TV picture tube

SAA1300 – Digital integrated circuit

Pro Electron took the popular European coding system in use from around 1934 for valves (tubes), i.e. the Mullard–Philips tube designation, and essentially re-allocated several of the rarely used heater designations (first letter of the part number) for semiconductors. The second letter was used in a similar way to the valves naming convention: "A" for signal diode, "C" for low-power bipolar transistor or triode, "D" for high-power transistor (or triode), and "Y" for rectifier, but other letter designations did not follow the vacuum tube mode so closely.

The three digits (or letter followed by two digits) after the first two letters were essentially a sequence number, with (at first) a vestige of the valve-era convention that the first one or two digits would indicate the base (package) type in examples such as in this family of general-purpose transistors:

... where x may be:

7 for high voltage

8 for general purpose

9 for low noise/high gain

Pro Electron naming for transistors and Zener diodes has been widely taken up by semiconductor manufactures around the world. Pro Electron naming of integrated circuits, other than some special (e.g. television signal-processing) chips, did not greatly take hold (even in Europe). Other popular designation systems were used for many integrated circuits.

Differences between Pro Electron and earlier valve-naming conventions

Unlike the tube naming convention, if there are two transistors in a single envelope, the type letter was never repeated - so a dual NPN RF transistor might get a type "BFM505" rather than something like "BFF505" for instance.

Although some of the most popular devices conform to a pattern of serial numbers that identified package type and polarity, many do not.

The letters assigned for the second character of transistor and diode type numbers differ in several ways, e.g.

"B" tends to be used for dual varicap diodes

"L" in the context of transistors designates RF power (transmitting) transistors; for valves it meant a high-power pentode tube (the usual choice for power RF)

"Z" is used for semiconductor Zener diodes instead of (full-wave) rectifier valves (tubes).

Frequently used first letters in European active devices

A Germanium (or any semiconductor with junctions in a material with a band gap of 0.6 to 1.0eV)

B Silicon (or band gap of 1.0 to 1.3eV)

C III-V semiconductors with a band gap of 1.3eV or more, like gallium arsenide in LEDs

D may be...

Semiconductors with a band gap less than 0.6eV, such as indium antimonide in infrared detectors (rarely used), or

(Mullard–Philips) 1.4V (or less) filament tubes

E (Mullard–Philips) tubes with a 6.3V heater

F Digital integrated circuits

P (Mullard–Philips) tubes for a 300mA series heater supply

R Devices without junctions, e.g. cadmium sulfide in a photoresistor

S Solitary digital integrated circuits

T Linear integrated circuits

U may be...

(Mullard–Philips) tubes for a 100mA series heater supply, or

Mixed digital/analogue integrated circuits

Electron tubes

See Mullard–Philips tube designation for details. A brief summary of just the more common letters is:

ECC81 / \ \\__ last digit(s) give serial number / \ \__ first digit(s) indicate base (3=octal, 8 or 18 or 80=Noval (B9A), 9=Miniature 7-pin (B7G). / \___ one letter per valve unit in the tube: D=1.4v or less A=single-diode (low power) E=6.3v* B=double-diode (usually shared cathode, but not always) P=300mA C=triode U=100mA F=pentode (low power) L=pentode (high power) Y=Single-phase rectifier Z=Full-wave rectifier * Note: some 6.3 volt heater types have a split heater allowing series (12.6 volt; the default for Noval pins 4 to 5) or parallel (6.3 volt) operation.

Semiconductor diodes and transistors

As listed above, the first letter gives the semiconductor type; the second letter denotes the intended use:

A 3-digit sequence number (or one letter then 2 digits, for industrial types) follows. Examples are:

With early devices, the number indicated the case type. Suffixes may be used, such as a letter (e.g. "C" often means high h_FE, such as in: BC549C). Other codes may follow to show gain (e.g. BC327-25) or voltage rating (e.g. BUK854-800A). A BC546 might only be marked "C546", thus possibly creating confusion with JIS abbreviated markings, because a transistor marked "C546" might also be a 2SC546.

Short summary of semiconductor diode and transistor designations

BC549C / \ \ \___ variant (A,B,C for transistors implies low, medium or high gain) / \ \____ serial number (3 digits or letter and 2 digits) / \_____ device type: A=Germanium A=Signal diode B=Silicon C=LF low-power transistor C=GaAs D=Power transistor F=RF transistor (or FET) P=Photosensitive transistor T=Triac or thyristor Y=Rectifier diode Z=Zener diode

Integrated circuits

Linear ICs begin with the letter "T", e.g. TAA570 limiter–amplifier and FM detector.

Logic ICs begin with the letter "F".

The FJ family is TTL (e.g. the FJH231 is a quadruple 2-input Open-collector NAND gate equivalent to the SN7401)

The FC family is DTL

The FD family is MOS.

Mixed analog/digital ICs begin with the letter "U", e.g. UAA180 LED bargraph A/D and driver.

FCH171 // \ \__ serial number, gives the count and type of gates for example // \___ H=gate ("Combinatorial circuit") J=flip-flop K=monostable Q=RAM R=ROM etc. FC=DTL FD=MOS FJ=TTL

Unfortunately the serial number does not specify the same type of gate in each family, e.g. while an FJH131 is a quadruple 2-input NAND gate (like the 7400), an FCH131 is a dual 4-input NAND gate.