Relays are an important component of an LCOS layout. Relays are used for power management, such as for Master Power controls, cab selection on multi-cab DC layouts and for Reversing Loops. Relays are also used to run stall motor and coil motor turnouts. Relays are controlled by DNOU8 boards.
What is an LCOS Relay? #
In LCOS, a relay consists of an off-the-shelf 5 volt relay module, wired in a specific way.
The Physical Relay #
The physical relay, is a commonly available 5 volt “relay module” with an optocoupler circuit that allows a 5 volt microcontroller to control household current. This type of relay guarantees electrical isolation between the two sides of the circuit.
To use an off-the-shelf relay module, the trigger type must be set (by jumper on the relay) to LOW, and the IN trigger connections are attached to ports on DNOU8 boards. VCC and GROUND should be attached to layout +5volt and GND respectively. NC (Normally Closed), NO (Normally Open) and COM (Common) contacts are wired according to the application, as shown below.
Logical Relay Types and How They Are Wired #
LCOS uses physical relays, wiring and coding to synthesize several different relay types out of basic single and double relay modules. The available switching types are a mix of conventional and specialized relays:
1. Standard SPDT
2. Standard DPDT
3. D3DT – This relay emulates a center off, DPDT momentary switch. It was specifically developed to control two-wire coil turnout motors (Kato, Atlas, etc.). The logical relay is composed of a double relay module, wired for tri-state (ON – OFF – ON) operation. The diagram below includes a recommended 1000μf capacitor when used for turnout control.
4. SPDT BREAK-MAKE – This is a compound relay that breaks the circuit before switching between input poles. Use this relay to select one of two inputs, then energize the circuit. This type of relay can be linked to turnouts for providing a power feed to turnout frogs; the break before make feature prevents inadvertent short circuits.
5. SPDT SELECT-ENERGIZE – This is a compound relay similar to the SPDT BREAK-MAKE, except it has an output select instead of an input select. Use this relay to select one of two outputs then energize the circuit. This relay type is used to run 3-wire coil turnout motors (Atlas snap-track, Peco, etc.). NOTE: The common wire from each turnout motor should be connected to layout GROUND.
Using Relays with Turnouts #
Relays are used to run coil motor and stall motor (Circuitron Tortoise; SwitchMaster) turnouts. Note that double relays require two DNOU8 ports. When setting up relays in the Configurator, “port 1” should be the port connected to IN1, or the bottom relay. “Port 2” should be the port connected to IN2, the top relay.
Below are the three most common wiring scenarios: