Circuitron
Emergency Flasher

.080" Yellow
Walthers Part # 800-3023, p. 773 Walthers 2012 HO Scale Reference
A scale, $19.95, not currently in stock at Walthers, Expected: Unknown

 
A low-cost circuit that alternately flashes two LEDs at a constant rate. Animate emergency vehicles, signs, barricades, towers, etc. Simple to install. Powered by a 9V battery, or by using PS-3.