Michael does a good job designing stuff. This signal driver
he designed can drive any standard three aspect color light
signal, B&O CPL, or Pennsy PL. He has these drivers installed
in a rather large private HO pike, and has experienced very few problems
with them since installing them in 2000.
Signal Driver Overview
This board is intended for use with model
signal systems using a common anode system of 3 color LEDs in each head or in
the case of PRR Position Light (PL) 3 series LEDs in each aspect. It also has
the ability to drive one other LED, such as the single red LED in another head
on an absolute signal or the qualifier in B&O Color Position Light (CPL)
signals. The circuit is designed to permit each more restrictive signal
indication to override any more permissive indication. The default aspect is Clear.
Mechanical Specifications
This board is made out of fiberglass reinforced resin, 0.062" thick. Overall
size, without connectors is 1.08" x 3.20". The board has a black
soldermask and white silkscreened legend/mask. Edge
card fingers are on 0.1" centers and intended for use with Sullins EZC10DREH or
equivalent connector. Outputs to the LEDs on the signal mast are on a 5 contact Waldom/Molex
KK type connector with 0.1" centers. All exposed pads and edge card connections
are plated with tin/lead.
Circuit Description
This board is designed to operate from a 12 volt regulated power supply.
All inputs are active low - that is, a "low" going signal
(or connection to ground) will activate the function. Diode isolation is
provided to allow multiple devices to be connected to the same electrical signal
without interference. Pull up resistors of 10K ohms are provided on the board to
insure unconnected inputs will be in a known state - off or non-activated.
All logic devices are 4000 series or 74C series CMOS.
An enable input is provided to allow approach lighting of the signal. Grounding
the \EN input on pin 6 will turn the LEDs on to display the selected indication. If
approach lighting is not desired, the enable jumper on the board should
be installed. This will keep the signals lit all the time.
The red,
yellow, and green
LED outputs are open collector transistors capable of driving up to 500 mA each
at 40 volts with an external power source with the proper selection of series
resistor. Pin 1 on the connector, is typically used to provide power to the
signal head. Normal operation is to select resistor values to match the
intensity of each color LED. Nominal values are installed to match many common
LEDs.
The marker is connected directly to ground
when the jumper is installed in the MKR position. The enable jumper should also
be installed when using this option. When in the CPL position, it is driven by
the output of the CD4069UB and is limited to a total of 3.5 mA divided between
the LED output and the \MKR output pin. The CPL output can be selected for
absolute or permissive operation. In the absolute mode, the marker is blanked
when the main head is displaying a red stop signal. The permissive mode allows
the marker to remain lit. In either mode, the marker is blanked when the signal
is not enabled unless the home input is low.
Installation and Operation
In general usage, the mating Molex connector
housing is loaded with pins attached to the signal head. A 12 volt supply is
furnished on pin 1 for common anode signal heads. Green is wired to pin 2,
yellow to pin 3 and red to pin 4. A CPL qualifier light or fixed red signal
head can be connected to pin 5.
The input edge card connector is wired with
signal system ground on pin 9, and the 12volt regulated supply on pin 10. The
enable pin 6 can be jumpered to the ground pin 9, (or the enable jumper on the
board can be installed), if this signal does not require approach lighting.
The \HOME pin 2 is connected to the output
of the current detection circuit of the block protected. The \Rin inputs on
pins 3 though 5 can be used to force a red stop indication whenever they are
low. Note that these inputs will not force the display to be enabled like the
\HOME input. These inputs should be connected to anything that should force a
red display, like a turnout set against the direction of travel or optical
detectors at the ends of the block. The \DIST line is usually connected to the
\Rout line of the next signal, or the current detector protecting the following
block. This will cause the signal to display a yellow approach indication
whenever the next block is occupied.
Below is a photograph of the circuit board, and below that is the schematic.
Connections to the signal are on the left, inputs are on the right.
I love trains, and I love signals. I am not an expert. My webpages reflect what I find on the topic of the page. This is something I have fun with while
trying to help others.
Please Note: Since the main focus of my two websites is railroad signals, the railfan guides are oriented towards the signal fan being able to locate them.
For those of you into the modeling aspect of our hobby, my
indexa page has a list of almost everything railroad oriented
I can think of to provide you with at least a few pictures to help you detail your pike.
If this is a railfan page, every effort has been made to make sure that the information contained on this map and in this railfan guide is correct. Once in a while,
an error may creep in :-)
My philosophy: Pictures and maps are worth a thousand words, especially for railfanning. Text descriptions only get you so far, especially if you get lost or
disoriented. Take along good maps.... a GPS is OK to get somewhere, but maps are still better if you get lost! I belong to AAA, which allows you to get
local maps for free when you visit the local branches. ADC puts out a nice series of county maps for the Washington DC area, but their state maps do not have the
railroads on them. If you can find em, I like the National Geographic map book of the U.S..... good, clear, and concise graphics, and they do a really good job
of showing you where tourist type attractions are, although they too lack the railroads. Other notes about specific areas will show up on that page if known.
Aerial shots were taken from either Google or Bing Maps as noted. Screen captures are made
with Snagit, a Techsmith product... a great tool if you have never used it!
By the way, floobydust is a term I picked up 30-40 years ago from a National Semiconductor data book, and means miscellaneous
and/or other stuff.
Pictures and additional information is always needed if anyone feels inclined to take 'em, send 'em, and share 'em, or if you have something to add or correct.... credit
is always given! Please be NICE!!! Contact info is here
Beware: If used as a source, ANYTHING from Wikipedia must be treated as being possibly inaccurate, wrong, or not true.
