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.
- Design 225VAC 400Hz inverter that can supply ?mA (?W)
- BOM
- WiFi interface board
- Firmware
- Tests
- Example code
- Documentation
- 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
- some characters are lower case and some are missing strokes
- 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
- 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
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-
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)
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-
SmartSocket for Alien Font displays
- use same protocol on daisy-chained 9600 baud RS232 (3v3?)
- 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)
- 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"
- mqtt listener