On a recent visit to SoCal from the UK we got a Chinese made, 200 watt transformer at Frys Electronics for $30 to run her hair straighteners (rated at 60 watts). It has an on/off switch and another for stepping up or down. Stepped up to 220 from 115, as soon as the straighteners came on it emitted a loud buzz from the vibrating case. Running the cellphone adaptor or simply switched on it made a low level hum. Now the adaptor is over here in the UK stepping the 230 down to 110 to run our Nakamichi tape deck (rated at 35 watts). The case still vibrates when it's on but with no hint of complaint like it did when stepping up for the hair iron. The tape deck performs as always. Any suggestions for what to use to internally damp the case? A block of porous rubber? It's perfectly silent when I damp it with my hand. Of some note, the fine print with the transformer says that stepping up halves the wattage rating stated on the box.
