The flashing light signal is particularly useful as a monitor during pulse transmission, when the operator may be engaged ... that the primary power supply Is derived from a 12-volt storage battery, or the 32-volt lighting circuit of the locomotive.
|Title||:||Scientific and Technical Mobilization, Hearing, Before a Subcommittee ..., S. 702 ..., March 30, 1943|
|Author||:||United States. Congress. Senate. Committee on Military Affairs|