We have all watched electric locomotives, traction vehicles or trolleys as they move along the rails and have seen the sparks created by the pickups (pantographs or spring-loaded poles) as they travel along the overhead (catenary) wires. This simulator is designed to reproduce those intermittent sparks of varying intensity for either two outputs (for dual pantograph applications) or a single output, for one pickup like many early-era trolleys had. The tiny size of Ngineering Nano white LEDs is perfect for this application.