Typically, 220/110 volt transformers warn against using them with higher wattage devices which have electronics. Some transformers have a Low setting for electronic and motorized devices up to 50 watts and a Hi setting for non-electronic heating devices up to 1600 watts.
Why are these transformers not compatible with higher wattage devices with electronics? What might happen to a 110 V coffee maker with electronics if used with a 220/110 V transformer?
I have seen some Foreign Travel Voltage Converters with a low power and hi power switch. Is that what you meant? The converters are meant to allow someone to use 120V USA products in a place that provides 240V power.
Let me quote from a customer review of a Dual Wattage Travel Converter at amazon.com that seems relevant:http://www.amazon.com/Recoton-ADF1650-Wattage-Travel-Converter/dp/B000028F42
This item offered here (Recoton ADF1650 50/1600W Dual Wattage Travel Converter) is actually two different converters built into one package. At LOW setting (up to 50W), it uses a small AC transformer to convert 220V sinusoidal waveform into a 110V sinusoidal waveform. This is the preferred approach which works well for any low power appliance.
At HIGH setting (50-1600W), this convert simply uses a solid-state switch inside to chop off part of the 220V sinusoidal waveform. The resulted waveform, as seen by the appliance, is highly distorted and is far from an 110V sinusoidal AC voltage.
For a purely resistive appliance (such as travel iron or water heater) it works just fine irregardless of different voltage waveform. But if you ever try to power an electronic appliance (such as TV, computer or battery charger) with this distorted 220V waveform, it will probably be fried in an instant!
If I understand this correctly, it is saying that at the 1600W high setting, the converter simply switches the output on and off to block half the 220V AC waveform. It is applying 220V half the time so the amount of power provided is the same as normal 110V AC (half of 220V).
I can see how this can fry some
electronic components that cannot handle the 220V at all. I would be willing to bet that things like laptop computers would handle it just fine.