Skip to main content
Tube Tinker — Electron Tube Database
Alternatives & variationsDownload PDF datasheet

Nixie ·Nixie

LL551

Cold-cathode numeric or character indicator cross-referenced to RFT Z561M. The comparison catalog supplies striking, maintaining, extinction, current, and display information for the RFT type while cautioning that comparable tubes are not necessarily electrically identical.

Directly heatedCold cathodeCommon cathodeDissimilar
Sections
1
Base
13-17 TGL 68-87
Socket code
B13B
Base pins
-
Nominal heater
-

Description

LL551 is a cold-cathode numeric or character indicator tube listed in the supplied German comparison catalog as comparable to RFT type Z561M. The catalog publishes 145 V anode striking, 135 V maintaining, 120 V extinction, a 1–2.5 mA cathode-current range, and associated display and mechanical data for that RFT type. The source explicitly cautions that comparable tubes are not necessarily identical, so these mapped RFT values are retained as comparison data rather than asserted as exact original-manufacturer ratings.

Socket description

B13B Nixie 13-contact

General specifications

Tube and section characteristics

Properties common to every published source and operating point.

Heater and base

Base
13-17 TGL 68-87
Socket code
B13B
Base pins
-
Nominal heater voltage
-
Nominal heater current
-
Parallel heater voltage
-
Parallel heater current
-
Series capable
No

13-17 TGL 68-87 - Terminal pinout

Electrical assignments shared by every tube using this base designation.

No verified pinout is recorded for this base designation.

Section ratings

1 physical section, each with unique specifications.

Section 1

Nixie

X-ray radiationInterelectrode capacitances
Max cathode current
2.5 mA
Regulator minimum current
1 A
Regulator maximum current
2.5 A
Regulator starting voltage
145 V
Regulator maintaining voltage
135 V

Cold-cathode display section; promoted starting/maintaining voltages and current range are published for comparable RFT type Z561M.

Source-dependent data

Operating conditions by source

Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.

Data set 01

1971 Nixie RFT

Published operating points and test conditions from this source.

SECTION 1

Nixie

Other

  • Comparable RFT Type

    Z561M

    Catalog cross-reference; comparable types are not guaranteed identical

  • Minimum Operating Supply Voltage

    170 V

    Published for comparable RFT type Z561M

  • Cathode Current Minimum

    1 mA

    Published for comparable RFT type Z561M

  • Cathode Current Maximum

    2.5 mA

    Published for comparable RFT type Z561M

  • Peak Cathode Current

    10 mA

    Published for comparable RFT type Z561M

  • Ambient Temperature Minimum

    -50 °C

    Published for comparable RFT type Z561M

  • Ambient Temperature Maximum

    70 °C

    Published for comparable RFT type Z561M

  • Displayed Symbols

    special symbols/characters

    Published for comparable RFT type Z561M

  • Reading Direction

    front

    Published for comparable RFT type Z561M

  • Symbol Height

    15.5 mm

    Published for comparable RFT type Z561M

  • Maximum Viewing Distance

    10 m

    Published for comparable RFT type Z561M

  • Mounting Orientation

    Pin 8 uppermost

    Published for comparable RFT type Z561M

  • Maximum Bulb Height

    26.5 mm

    Published for comparable RFT type Z561M

  • Maximum Bulb Diameter

    30.1 mm

    Published for comparable RFT type Z561M

Characteristic

  • Anode Striking Voltage

    145 V

    Published for comparable RFT type Z561M

  • Anode Maintaining Voltage

    135 V

    Published for comparable RFT type Z561M

  • Anode Extinction Voltage

    120 V

    Published for comparable RFT type Z561M