IO4-SignalDriver

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IO4 Output adapter driver for a 2-head signal mast

IO4-SignalDriver-Graphic
IO4-SignalDriver-Graphic

 

 

IO4-SignalDriver Version 2.0

Not built

Takes an IO4-Output and drives 2x 3-LED common Anode signal heads using a demultiplexor logic chip. Designed in conjunction with Jay Beckham for his South Shore Lines layout Circuit testing:

  • The board needs to share a common ground with the remote controller (CMRI SMINI…) as the RJ45 only carries control signals
  • Drive the board with 5V DC through the IO4 connection
  • Signal heads / LEDs are “common anode” - pin4 of the signal head connector is VCC, the “colors” pins are driven LOW to energize the LED.
  • All control lines are pulled up logically on the signal driver board.
  • The board can drive 2x signal heads, each with R, Y, G and DARK aspects
    • Control signals 1 & 2 and 3 & 4, each control one head:
      00 - Green
      01 - Yellow
      10 - Red
      11 - Dark
  • The discrete resistors set a safe limit on the current allowed to the LED, and the trimmer pots can be used to further adjust the brightness.
  • The exact value depends on the specific attributes of the LED variety being used - specifically the forward voltage drop across the device. This info is found in the data sheet for the LED in question, or can be found experimentally.
    • Example: with a 5v supply and a LED that drops 2.2v, the resistor sees (5-2.2 = 2.8v). If we wish to limit the max current to 15mA, we need a fixed resistor of (2.8v / 0.015 = ~180 ohms). If we add a 500 ohn trimmer resistor, that lets us adjust the current from 15mA max to about 4mA min. High efficiency LEDs might need even LESS current, so upping the fixed resistor to 470R or even 1K0 might be appropriate.

Schematic
Schematic
Bot Silk
Bot Silk
Board
Board
Top Silk
Top Silk

Download IO4-SignalDriver.gerbers.zip - Gerber Fabrication files
Download IO4-SignalDriver.parts - Parts List (spreadsheet data)

 

IO4-SignalDriver.bom

Parts Value Package Quantity Library Type/Feeder
C1 0.1UF 0603-CAP 1x SPCoast 19
CON2, CON3 2mm 4P-2.0 2x SPCoast PTH
CON4, CON5 3.5mm SCREWTERMINAL-3.5MM-4_LOCK 2x SparkFun PTH
RN1 4k7 SIL5 1x resistor-sil PTH
IC1 74LS139D SO16 1x SPCoast NONE
R1, R2, R3, R4, R5, R6 330R 0603-RES 6x SPCoast NONE
P1, P2, P3, P4, P5, P6 500R P-3319 6x SPCoast PTH
BOARD1 BOARD BOARD-DINRAIL-3.17INX10CM 1x SPCoast PTH
FID-LR, FID-UL FIDUCIAL FIDUCIAL_1MM 2x SPCoast NONE
U$2 OSHW OSHW-LOGO-L 1x SparkFun PTH
J1 RJ12/6 RJ25-PANEL 1x SPCoast PTH
CON1 RJ45 RJ45-NO-SHIELD 1x SPCoast PTH

This technical documentation is licensed under the CERN Open Hardware Licence v1.2

Tags: eagle Signal