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linked block signals

Block Signal Control for Model Railroads

Infrared (IR) train detection eliminates the need for insulated rail gaps and resistor wheel sets.

One TS2 circuit operates two LED train signals on a single bi-directional track:

signals at block boundary
Two block signals at a block boundary, single 2-way track

One TS2-D circuit operates two LED train signals on a double-track line:

signals for dual track
Two block signals at a block boundary, dual one-way tracks

 Any number of TS2 or TS2-D circuits may be linked to operate a series of cascading block signals:

linked block signals, single track
linked block signals, dual track

Simple installation

  • Don't worry about rail gaps or resistor wheel sets. The TS2 includes two very reliable infrared train detectors to sense train activity.
  • Don't worry about the polarity of your LED signals. The TS2 is "polarity smart" - it automatically adapts to common-anode (+) or common-cathode (-) signals.
  • Don't worry about LED resistors. Current-limiting resistors are built into the TS2.
  • Don't worry about programming or addressing. The TS2 is ready to wire up and go!
approach signal
The installation of a TS2 signal system is documented on the Michigan Interstate St. Clair Sub blog site, including photos, video and a detailed narrative.

Greg McComas photo

Designed with modular layouts in mind

  • Two adjoining layout modules that each have TS2 or TS2-D controllers can be linked with just two wires. The signals on the two modules will then operate together.
  • If the next module does not have a TS2 / TS2-D, then your TS2 / TS2-D will automatically sense this and will operate in a timed mode. Signal aspects will change after a train goes by according to a built-in timer.
    On the TS2 (single track) only, the timer's speed depends on the train's speed. Signal aspects will change more slowly after a slow train goes by because a slow train presumably will take longer to clear the distant imaginary blocks than a fast train.
block signal circuit
  • The pulsed infrared train detectors are not affected by changes in room lighting. Moving to a new location or turning down the lights for night operation? No re-adjustment needed!
  • 3-aspect or 4-aspect operation (see below).
  • Lamp on/off fading effect.
  • Spring terminal blocks for quick wire connections.
  • Power required: 9 to 16 volts AC or DC.
    One PS906 power supply will power up to ten TS2 or TS2-D circuits with signals.
  • The TS2 and TS2-D are designed specifically to work with LED block signals of any scale.
    For signals that have incandescent bulbs, solid state relays such as our SSR6 must be used between the TS2 and the signal.
  • Block signals sold separately:
TS2 single track installation guide PDF
TS2 Track Signal Control  $39.00
for use on single 2-way track
Includes two IR sensor sets with 2-ft (60cm) wire leads
TS2-D double track installation guide PDF
TS2-D Track Signal Control  $39.00
for use on dual 1-way tracks
Includes two IR sensor sets with 2-ft (60cm) wire leads
TS2 3-pack  $99.00
for use on single 2-way track
Three circuits + six IR sensor sets with 2-ft (60cm) leads
TS2-D 3-pack  $99.00
for use on dual 1-way tracks
Three circuits + six IR sensor sets with 2-ft (60cm) leads
signal types
2 LED signal
2 LEDs
D typeG type
3 LEDs
incl. searchlight signals
with single tri-color LED
CPL with marker
B&O color position light
with marker
bi-color searchlight
Searchlight with
bi-color LED (red/green)
2-wire or 3-wire
[see note below]
2 aspects
• clear
• stop
• green
• red
• green
• red
• green
• red
• vertical
• horizontal
• green
• red
3 aspects
• clear
• approach
• stop
• green
• yellow
• red
• green
• yellow
• red
(marker on or off)
• vertical
• diagonal
• horizontal
• green
• yellow
• red
4 aspects
• clear
• advance appr
• approach
• stop
• green
• flashing yellow
• yellow
• red
• green, marker on
• yellow, marker on
• yellow, marker off
• red, marker on
• green
• flashing yellow
• yellow
• red
Note: There are two kinds of LED searchlight signals:
  • Bi-color (red/green) - With two or three wires, this is the older type. The red and green portions of the LED are illuminated together to imitate a yellow color. The effectiveness is highly variable depending on the LED itself, ambient lighting and viewing angle. Looking from one side, the 'yellow' signal may appear almost red, and from the other side it may appear very green.
    Though the TS2 / TS2-D has a jumper setting that allows you to adjust the yellow aspect with more red or more green to compensate, we recommend evaluating one signal first before purchasing signals in quantity.
  • Tri-color (red/yellow/green) - Newer searchlight signals are available with tri-color LEDs that have a real yellow chip inside the LED, plus the red and green chips. You can easily spot these signals because they have four wires (red, yellow, green and 'common'). They show a real yellow color from all angles and under all lighting conditions. Use tri-color LED searchlight signals for best appearance.

TS2 / TS2-D Limitations:

  • The TS2 / TS2-D detects trains only when they pass by the block boundary.
    When linked to another TS2 / TS2-D - After a train enters a block, the TS2 / TS2-D assumes that block is occupied until a train exits that block. If part of the train uncouples and remains in the block while the rest of the train exits the block, the TS2 / TS2-D can only sense that a train exited the block and will then show the block to be clear.
    Therefor, where track is not visible to operators, supplemental detection may be used with the TS2 / TS2-D to detect stranded rail cars or other obstructions.
  • While its power is turned off, the TS2 / TS2-D cannot sense if trains are added or removed from the track. Therefor, when power is turned on, all signals will initially show an 'approach' aspect to let operators know they should proceed with caution. After the first train passes the infrared sensors, the signals will operate normally.

Interlocking controls:

Forcing a 'stop' condition:
  • A signal may need to show a 'stop' indication for an open turnout or draw bridge in the block, for an indication from another train detector, or by command of a dispatcher. Use a switch or relay contact to connect a 1,000 ohm (1k) resistor between the Link ('LE' or 'LW') and 'C' of the TS2 / TS2-D to force a 'stop' indication. This works in linked or stand-alone mode.
Clearing a block:
  • An 'occupied' ('stop') signal indication may be manually cleared by momentarily shorting Link ('LE' or 'LW') to 'C' with a push button. You may want to do this if a train exited a block by some route other than passing a TS2 / TS2-D at the block boundary - perhaps it took a branch line or was removed by hand.
external controls
Closing switch S1 or S1-B will force #1 eastbound signal and #2 westbound signal to show 'stop.' These contacts may be linked to a drawbridge, turnout points, a train detector or a dispatcher's switch.
Momentarily closing switch S2 will clear the block between TS2 #1 and TS2 #2.

Use with a dual head signal:

If the 'M' terminal of the TS2 or TS2-D is not used for a B&O marker lamp or for the middle lamp of a PRR signal, the 'M' terminal can be used to light an LED on a second signal head.
In some places railroads will mount two signal heads on one mast, one below the other. Railroads will use the lower signal head for different purposes depending on location and situation. It's up to you to decide what information the second signal head will display to the train crews on your railroad.
For example:
A turnout is located to the east of a dual head signal. We decide to use the 2-light lower signal head to indicate the position of the turnout points.
When the turnout is aligned for the main track, the upper signal head displays the condition of the main track and the lower head shows red.
When the turnout is aligned for the siding or branch track, the upper head shows red and the lower head shows yellow.
The two sets of electrical contacts are linked to the switch machine. These can be internal contacts such as are built in to Tortoise™ and Cobalt™ switch machines, or they can be contacts of a latching relay that operates in parallel with the switch machine.
The contact on the left connects the 1,000 ohm ('1k') resistor in parallel with the 'LE' and 'C' terminals, the two east link connections, when the turnout is aligned with the branch line. This forces the upper signal head to show red.
The contact on the right routes power to either the yellow or the red LED in the lower signal head.
dual head signal placement
An example of a dual head signal located ahead of a turnout.

connecting a dual head signal
An example of using the 'M' terminal to power an additional LED.
For more details, download the
TS2 single track installation guide PDF
Or, download the
TS2-D double track installation guide PDF

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