On a lot of model railroad layouts, I noticed something that always felt a little off: every light in every room of every house is on — all the time — and none of them ever turn off.

That didn’t feel very realistic.

So I put this together.

This 12-Volt AC Light Timer is designed to add more natural, independent lighting behavior by automatically turning lights on and off in adjustable cycles. Instead of everything lighting up at once, you can have lights change over time — the way they do in the real world.

It connects directly to a 12-volt AC output from a transformer and is equipped to handle that power safely, delivering a controlled output to your lighting circuit. It also works just as well with DC lighting systems.

Fully Adjustable Timing Control

Using the built-in buttons (Up, Down, Mode, Enter), you can set:

• On time
• Off time
• Delay before turn-on
• Repeating on/off cycles

Timing is continuously adjustable from 0.1 seconds up to 999 minutes, so it can handle anything from quick lighting changes to long, slow day-and-night style cycles.

Each timing parameter is set independently, giving you fine control over how the lights behave.

Remembers Its Settings

Once programmed, all settings are stored in memory.
Turn the transformer off, turn it back on later, and the timer resumes cycling automatically — nothing needs to be reset.

Quiet, Solid-State Operation

This unit uses solid-state MOS switching, not a mechanical relay:

• Completely silent operation
• No clicking, arcing, or sparking
• No electromagnetic interference
• Long service life

It’s designed to handle typical low-voltage lighting loads smoothly and reliably.

Simple Connections

• Input leads connect to your transformer’s 12-volt AC terminals
• Output screw terminals connect to your lighting circuit

No software, no computer, no special tools required.

Important LED Note

If you are using LEDs that are not already rated for 12 volts, be sure to use the appropriate resistor in line with the LED.
This timer provides a 12-volt output, so your lighting must be properly rated to avoid damage.

Features at a Glance

• Works with 12-volt AC or DC systems
• Timing range: 0.1 seconds to 999 minutes
• Independent on/off timing settings
• Silent solid-state switching
• Emergency STOP function
• Reverse-polarity protection
• Automatic display sleep mode
• Settings retained after power loss

This is a simple way to add life and realism to lighting, instead of having everything stuck in the “always on” position.