Some car batteries must be lifted out of their holding trays, while others can be charged as they are. In most conventional vehicles, you likely won’t have to remove the battery to charge it. In the ...

A number of broadcasting stations using frequency modulation on the ultra-short wave-length band below 10 metres have been in operation for some years. Frequency Modulation By K. R. Sturley. Pp. 58.

FREQUENCY-MODULATION, or the technique of varying the frequency of radio waves for signalling purposes, has been known and used for many years ; but it was not until Armstrong in the United States ...