It's always present, but once the adhesive starts to break it gets louder. Over time that adhesive starts to break apart and the laminated layers separate from each other slightly. That magnetic field acts between the adjacent plates stretching and squeezing the adhesive and insulation between them. The higher capacitance may do a marginally better job of removing 60-cycle AC line 'hum' from the audio output of the radio. Likewise, you could replace a 20 with a 33. Lots of metal plates, each with an induced magnetic field. For example, when replacing a 10-mfd electrolytic capacitor in the radio's power supply, it is OK to use a 20-mfd or 22-mfd replacement. So you have lots of steel plates stuck together, but not only that:Įach lamination is insulated from its neighbors by a thin non-conducting layer of insulation. Later designs constructed the core by stacking layers of thin steel laminations, a principle that has remained in use. This is done because:Įarly transformer developers soon realized that cores constructed from solid iron resulted in prohibitive eddy current losses, and their designs mitigated this effect with cores consisting of bundles of insulated iron wires.
#VINTAGE RADO LOUD HUM SERIES#
That ferrous material is not a solid lump of metal, but a series of plates laminated together with adhesive. A transformer, as you well know, is made up of two or more coils around a core of ferrous material.