These displays are driven by current pulses. Direction of the pulse is determining how you set the display. It is also important to keep length of the pulse within a range in order not to overheat driving coils as well as limit current of the pulses. If you are planning to build your own driving circuit, we can help. We also offer ready controllers.

Just add RS485 signal and 24V and you are ready to go! The segments are molded from a white UV resistant material to ensure high visual impact over a wide ambient light range, including direct sunlight. The background color is matte black.

  • visibility

    White flags on black background – what to expect more? The same visibility as black pen on a white paper. You can read it with pleasure and without being tired. Very pleasant and non – aggressive display which can be fitted perfectly into good indoor design or highly critical industrial application with human operators looking 24/7 at thousands of displays. The light reflecting segments provide excellent visibility over a wide range of ambient light conditions, and are readable up to 50ft (15.2m) away. Visibility increases with an increase in the ambient light level.

  • reliability

    Nothing to burn out. Simple, proven principle. Can last for years, and this means 10 years or 15 years. If you want to compare it with LED time life, these displays can show information for 200’000 hours+ without showing a small evidence of being tired. There are no lamps to burn out and no mechanical linkages to wear out. The segments are rated for over 250 million operations. The modules are highly resistant to shock and vibration and are particularly suited to mobile applications with wide temperature extremes. Millions of these units have been in operation worldwide for over 20 years. No other display technology can match this performance and reliability.

  • economy

    Power is only required to change the data displayed. Magnetic memory retains the display indefinitely without power being applied. This makes this display the perfect solution for battery or solar driven devices because you can limit power consumption very much. Practically, you can keep all control circuits off for most of the time and wake them up only to measure your value and show it on your displays. Consisting of 7 electromagnetic operated light reflecting segments, the module can display the digits 0-9, plus a limited selection of alpha characters.

Consisting of 7 electromagnetic operated light reflecting segments, the module can display the digits 0-9, plus a limited selection of alpha characters.

  • A display flag is a moving part which is either visible to an observer or hidden. Each display flag includes a permanent magnet. The selected flag changes position according to the controlled change in the magnetic field of a core of a closely coupled electromagnetic coil. 

  • The control signal sets orientation of magnetic domains inside of the coil’s core showing or hiding the flag. The flag remains in the position to which it was last turned until the magnetic field is reversed by another current pulse. 


  • This principle of operation is based on the same technology as a core magnetic memory - more then 60 years old invention that revolutionized computer industry (more here: www.computerhistory.org)

  • Mobile devices
  • Ground fault
    indicators displays
  • Designers clocks
  • Thermometers
  • Solar powered
    field indicators

These modules are manufactured on original Ferranti Packard and according to Ferranti Packard specifications


operating temperature: -40°C to 75°C storage temperature: -45°C to 85°C relative humidity: 5 to 95% non-condensing


coil resistance: 45Ω ±10% w 20°C coil temperature coefficient: 0.195°C/mW (free air) coil temperature MAX: 95°C

Current pulse data

current pulse amplitude MAX: (set current limit of driver circuit) 335mA (implies minimum coil voltage of 16 V DC) voltage across coil: 19 V DC pulse width: 1 ms

Segment mechanical turning time is within 15 ms maximum. At these coil drive parameters, the duty cycle for driving the same segment must be less than 5% (on/off time) therefore allow at least 900 ms before driving the same segment again.

This will ensure that the segment coil will not accumulate heat. PCB connection pinout

PWB connection pinout

+SET to -RESET current direction through the coil will cause the segment to be displayed. 
+RESET to -SET current in the opposite direction through the coil will cause the segment to be hidden.
All dimension in inches. 

Outline and Mounting
Application notes

The module must be protected from the temperature extremes created by sunloading on the display enclosure. A UV screening material should be included in the design of the enclosure window. Life test (at 14 operations per minute) is currently over 94 million operations without any failure.

During cleaning of the printed wiring board the head assembly should be separated from the base assembly, as the head assembly does not require cleaning. The use of fluorinated solvents will invalidate the warranty.