JAY EMRIE wrote in a message to ALL:

 JE> I have had a small lamp on my bed bookcase type headboard for
 JE> years. The pivotable arm finally got so loose it wouldn't stay put.
 JE> Picked up another one at an estate sale - that worked fine. Trouble
 JE> with it turned out to be a constant hum from the voltage reducing
 JE> xfrmr - even when the lamp was switched off. It used a #93
 JE> automotive bulb.

 JE> I finally got disgusted with it and bought a new one - halogen -
 JE> which does not hum when turned off.

 JE> Tore (literally - the screws that held it together were imbedded 1
 JE> 1/4" deep and had a head that matched  nothing I had) the old one
 JE> apart. The idiots had hard wired the input of the voltage dropping
 JE> transformer directly tp the 110 V AC input. The on/off switch only
 JE> switched the 12V output! No wonder it hummed when turned off or on!

I guess that makes for them being able to use a cheaper switch,  or something...

The transformer primary winding shouldn't draw all that much current when
there's no load on the secondary side.  If it hums,  it's because there's
probably a lamination loose in there.  Some sort of "stuff"
applied to it should quiet it down.

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