Tips and Jottings

Radio Record, Volume V, Issue 7, 29 August 1930, Page 23

Tips and Jottings

Transformer Care. AUDIO transformers having cores made up from stampings from sheets of one of the new steels may change their characteristics if by accident a relatively heavy current is passed through the primary winding or if the component is dropped. It is usual to heat treat the core stampings after they have been punched from the sheet in order to improve their magnetic properties, but it would seem that a user must exercise a certain amount of care, or the special properties will be destroyed. The manufacturers them’ selves handle the stampings with care during assembly, as it is known that even bending will impair the magnetic

properties of the steel. Using Two Speakers. THOSE possessing a modern cone speaker and an old-style highs pitched horn may easily adopt the mixes ing-panel idea employed by transmitting stations. The general purpose of a mixing panel for the home receiv er is to obtain mellowness and depth with just the desired degree of sharp ness for voice and distant reception. To do this, both speakers are cone nected in series across the output of the radio receiver, and each is shunte ed with a variable resistance. Both resistances should have a range of from 0 to 300,000 ohms for efficient cone trol. Separate resistors may be used, ol dual resistors mounted in a single anit. na nmennananenan eh fb bb bf bd >,