AfdDriver

alienFontDisplay

Display made of six eight-segment EL display units with per-display custom driver board and controller.

Scrolling display board that displays whatever string is published on a given MQTT channel over WiFi.

These displays were used in Russian tanks and missile launch consoles.

TBD

• Design 225VAC 400Hz inverter that can supply ?mA (?W)
• BOM
• WiFi interface board
• Firmware
• Tests
• Example code
• Documentation

Display Pinout

Alphanumeric Font

Single Display and Driver Board

Driver PCB

Schematic

EL Displays

IEL-O-VI C63.396.208-02

• Blue, Alien Font, Russian/Soviet Electroluminescent Display
• [0-9] and [A-Z] (after a fashion)
  • some characters are lower case and some are missing strokes
    • in particular, there isn't a center vertical stroke, so "T" and "I" are not so great
  • seems to have been designed for Cyrillic characters
• pinout
  • 1: common
  • 2: bottom horizontal (S)
  • 3: bottom right angled (M)
  • 5: n/c?
  • 7: left vertical (L)
  • 8: bottom left angled (M)
  • 11: top right angled (M)
  • 14: left vertical (L)
  • 17: top horizontal (S)
  • 20: top left angled (M)
• per-segment capacitance (estimates)
  • S (2x): 55 pFd
  • M (4x): 90 pFd
  • L (2x): 170 pFd

Power Supply Design

• Specs
  • 220VAC @ 400Hz
  • 0.5-3mA per display
    • four displays: 12mA (max)
    • six displays: 18mA (max)
• Design alternatives
  • drive audio amp into (CT?) step-up transformer
  • DC boost converter into H-Bridge

=========================

• notes

  • ~200V @ 400Hz
  • not squarewave -- filter or triangle wave for constant dv/dt
  • less bright at 50Hz, but last longer
  • need current limiting resistor if power source has low internal resistance
    • e.g., 330K ohm @ 220V @ 50Hz
  • 500 Hrs lifespan
  • sine/square voltage up to 250V and 400Hz-5KHz
  • decay time fractions of msec
  • at least 6usec pulse
  • no loss of brightness in pulses of 100usec at constant duty cycle
  • most of drop in brightness occurs in first 200 hours of operation
    • relatively flat after that
  • for best lifetime, maintain constant frequency and reduce voltage
  • use current limiting resistor for supplies with internal resistance less than 1Kohm
  • add 0.03-0.05ufd caps in parallel with electrodes to improve reliability
  • nomenclature
    • I: indicator
    • EL: electroluminescent
    • color
      • O: one color
      • M: multicolor
      • P: raster
    • size (13x sizes)
      • VI: 34x40mm
      • II: 13x35mm
      • IV: 18x26mm
    • number of dots indicate brightness
  • IEL-0-VI-101-246: 19x segment starburst with bar above and left and right commas
  • constant power mode
    • 220V @ 400Hz
  • constant brightness mode
    • 175-250V @ 1200Hz -- increases with service life
  • 0.5-3 mA current
  • DC will destroy the display
  • can't multiplex displays -- need driver for each segment
  • lifetime drops rapidly with supply frequency >400Hz

• Links

  • https://www.nixology.uk/el-displays/
  • http://www.155la3.ru/electroluminescent.htm?fbclid=IwAR3kzInl6R3qaqCM56aDhy-eqRuBEZQ2xA1R94jkRoaB9Y2xDsH_GoB88GI
  • https://www.youtube.com/watch?v=p6mNbgtnFK8
  • http://lampes-et-tubes.info/cd/cd143.php?l=e
  • http://www.nedopc.org/forum/viewtopic.php?f=65&t=11093
  • https://www-nedopc-org.translate.goog/forum/viewtopic.php?f=65&t=11093&_x_tr_sch=http&_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=en-US&_x_tr_pto=wapp

• Sparkfun EL Inverter (COM-10469 retired)

  • input: 12VDC
  • output: 70-110V (90V typ)
  • frequency: 800-3500Hz (2000Hz typ)

• Sparkfun EL Inverter (sourced from Amazon)

  • input: 5VDC
  • output: 225VAC (in afd circuit)
  • frequency: 5-7KHz (in afd circuit)

=======================================================================================

• SmartSocket for Alien Font displays

  • use same protocol on daisy-chained 9600 baud RS232 (3v3?)
    • http://tayloredge.com/reference/Circuits/1386SmartSocket/SmartSockets.pdf
  • build single-sided PCB that fits on back of display units
    • drive each segment individually
    • use common HV PSU
    • use circuits from SparkFun boards as they have been tested and shown to work
  • need to select a PIC to use as the on-board controller
    • PIC18F16Q41: same as PIC18F16Q40 but has an opAmp
    • PIC18F16Q40:
      • 14pin device has six GPIOs on PortA and another six on PortC
      • has 1/2 UARTs
      • 64KB program FLASH, 4KB SRAM, 512B EEPROM
      • 18x GPIO, 2/3x 8b timers, 17x channels of 12b ADC, 2x 8b DACs, 4x DMA
      • 32b CRC with scanner, vectored interrupts, temperature indicator, NCO, PWM/CCP
      • C compiler
        • CCS: http://www.ccsinfo.com -- $200-$500
        • Hi-Tech: http://www.htsoft.com -- bought by Microchip
        • Microchip: http://www.microchip.com -- free student mode
        • MPLAB C18: microchip
        • MikroC: free student version with limits
        • https://www.microchip.com/en-us/development-tool/C18
      • $1.5 at Mouser (in stock)
        • PIC18F16Q40-E/SO
        • https://www.mouser.com/ProductDetail/Microchip/PIC18F16Q40-E-SO?qs=sGAEpiMZZMv0NwlthflBi%252BydFA3s6SRqoyEH6IOSDHM%3D
      • example: https://github.com/microchip-pic-avr-examples/pic18f16q40-quadrature-decoder
        • RA2: UART Tx programmer?
        • RB7: UART Tx
        • RB5: UART Rx
        • RB4, RB6, RA4, RA5, RC0-RC7: GPIO
      • PPS re-mappable input signals can be moved from default locations to other ports
        • UART outputs: DTR1, RTS1, TX1, DTR2, RTS2, TX2, DTR3, RTS3, TX3
        • UART inputs: RX1, CTS1, RX2, CTS2, RX3, CTS3
      • pin allocation table (default)
        • RB5: RX1
        • RB7: CTS1
        • RC1: RX2
        • RC2: CTS2
        • RC3: RX3
        • RC5: CTS3
  • use shift registers?
  • use I2C port expander?

• display unit dimensions, pin and threaded spacer locations are not consistent across instances

• Use SparkFun EL boards for proof of concept testing

• EL Sequencer v23

  • https://www.sparkfun.com/products/12781
  • http://cdn.sparkfun.com/datasheets/Components/EL/SparkFun_EL_Sequencer_v23.pdf
  • ATMega328P processor on-board
    • use "Arduino Duemilanove or Diecimila" board with FTDI USB dongle
  • Gets HV from Sparkfun EL Inverter
    • not ideal -- need higher voltage and better frequency
  • Drives HV to all segments of all displays
    • EL Escudo Dos pulls display commons to HV_GND
  • D2-D9 used to drive EL_A-EL_H
    • EL_A: pin 2
    • EL_B: pin 3
    • EL_C: pin 7
    • EL_D: pin 8
    • EL_E: pin 11
    • EL_F: pin 14
    • EL_G: pin 17
    • EL_H: pin 20
  • Sends six (active high) TTL signals to EL Escudo Dos to enable each display
    • ADC_0 (JP4:2): display #1
    • ADC_1 (JP4:7): display #2
    • ADC_2 (JP2:8): display #3
    • ADC_3 (JP2:7): display #4
    • ADC_4 (JP2:6): display #5
    • ADC_5 (JP2:5): display #6

• EL Escudo Dos

  • https://www.sparkfun.com/products/10878
  • https://cdn.sparkfun.com/datasheets/Components/EL/EL_Escudo_Dos/EL%20Escudo%20Dos%20v21.pdf
  • Pulls display common lines (pin 1) down to HV_GND
  • EL_H: display #1 ... EL_C: display #6
  • gets HV_GND and TTL display unit selector signals from EL Sequencer
  • all SCRs have common HV connected to their tabs
    • and they have individual outputs to load and ground
  • need to cut HV to tabs and connect them to the display common signals
    • and short all load outputs to HV_GND

• misc

  • mqtt listener
    • mosquitto_sub -t /displays/# -F "%I,%t,%p"
  • commands
    • rssi
    • version
    • reset
    • rate[=]
    • scrollDelay[=]
    • pause[=]
    • display[=]
  • e.g., mosquitto_pub -t "/displays/afd//cmd" -m "display=abcdefghijklmnopqrstuvwxyz0123456789"