The key component is a transistor radio with a headphone plug. You can find these in garage sales, bargain bins, or on electronics surplus company web sites, such as All Electronics, which is where I believe I bought the radio shown in the photo here, specifically for this purpose.

A cheap set of headphones is the other part needed. Cut the headphones off. I made the wire as long as possible so that I could locate the radio somewhere under layout without having it interfere (space-wise) with all the things that normally go under a layout.

The final part is an amber LED. The amount of current coming out of the headphone jack of the radio is small, so no current-limiting resistor is needed. I soldered the LED to the wire and inserted the plug in the headphone jack of the radio.

Adjust the tuning and the volume to have the LED produce a flicker without going off or being full on.

As mentioned above, the circuit is real simple. You need a radio, headphones plug and wire, and an amber/yellow LED.

It is possible to attach several LED's to the wires. This would allow for flickering lights in various locations, such as in a machine shop, in a 55-gallon drum, or a burning building, all running from a single radio.