COMPASS HOUSEModel Engineering Manufacturing locomotives in 5" & 7¼" gauge since 1994 Electronic Diesel Engine Sound Module & Speaker Suitable for 5" & 7 1/4" Gauge battery electric locomotives. The module features simplified wiring to ride-on loco controllers. The ability to add extra speakers for even greater volume. The engine noise effect is directly linked to the regulator voltage and varies from a rhythmic idle sound when the loco is at rest, to a full-bodied "roar" when the engine is in motion, with turbo "whine" if required. The idle speed is fully adjustable, as are maximum revs, turbo level, cylinder level, tone and volume. Input voltage = 12V D.C. Supplied with full fitting instructions.