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© April 06, 2008
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Signal Track Circuit For Live
A simple track Circuit for operating signals on your railroad
Written by Robbie Diehl
main problem with Signals in our hobby is snow and rain on the track. Snow and
rain conduct electricity and will show the false presents of a train in a
block. I have tested this in both snow and rain and it works well. The circuit
works with the track completely submerged in water !!! The type of ballast that
you use and moisture content of your soil also effect the operation of the
circuit. I have used it with 1/4 minus crushed river rock ballast and volcanic
cinders with good results. This is not a fail safe system. What I mean by
this is that it does not protect you from component failure or power loss. Full
size railroad signaling that costs thousands of dollars protects against a
false clear (Green) indication with many system back up circuits and is fail
safe. I will not be responsible for damages caused by this circuit. You use it
at your own risk.
|With that said all you need is two components for the circuit.
Radio Shack Reed Relay Catalog #: 275-233 200 OHM 2 Watt Resistor (I use the
NTE Brand Just make sure it is 2 Watt) DO NOT SUBSTITUTE PARTS. PLEASE NOTE
THAT THIS IS A 2 WATT RESISTOR You can build these on PC Boards using the Radio
Shack PC Board Kit Catalog #: 276-1576 and make 4 circuits at once. (see
diagram on right). The reason you should do this is because a typical siding
has at least 4 blocks.
- 1 Block for the siding
- 1 Block for the Mainline
- 1 Block for the East Approach
- 1 Block for the West Approach
Print the circuit board template
out and tape it to the PC Board. Full size when printed should be 3 inches by 3
˝ inches. Drill the holes then connect the holes like the lines on the template
using the ink pen in the Kit. I use a smaller drill bit then the one in the
Kit. Use a drill bit that will fit the biggest wire you solder to the PC board
snugly. Follow the instructions in the PC board kit to etch the board then
solder the components in (right).
click to enlarge
click to enlarge
|I use the Oaktree Systems Model RR interface
to control my signals and the Railroad & Company Software
http://www.freiwald.com/ Oaktree will be
coming out with their own software this year that is less expensive then the
Railroad & Company Software. The output of the track circuit board (Yellow and
Blue Wires) connects to one of the inputs of the Oaktree I/O 48 board.
|I also use the Maxstream 9excite 900 MHZ radios to send a 232
signal from my computer to the Oaktree 485 converter and then to the I/O 48
board. I buy the 900MHz 4mw Radio Modem Development Kit 38400 Baud from B&B
Electronics Part number XC09-038-DK.
click to enlarge
|This kit gives you two radios that is enough to
signal your first siding. Be sure to pick a radio set that works for your
conditions i/e distance from the Base Station to Remote Station. You can
connect the output of this circuit to any circuit that you would like to
control your signals. The Reed Relay is always closed until a train enters the
block then the Reed Relay will open.
Written by Robbie
|Editors Note: There are dozens (if not more) ways
to configure train detection and signaling circuits. We are interested in how
it's done at your railroad. Please send us an article explaining how you
do it. E-mail me today.
Information contained in this article is for reference only.
We at discoverlivesteam.com and our authors are not responsible for any loss
that might occur from the practical application of ideas presented here.
Regardless of what is contained here, always protect your projects with sound
engineering techniques. Use current limiting devices and ground fault
protection on all circuits. To not rely on signals to provide proof positive
that track is clear of traffic.
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