# Can you use an international power adapter with a charger? **URL:** \ **Category:** Factual Questions\ **Created:** [October 10, 2006, 5:45pm UTC](https://boards.straightdope.com/t/can-you-use-an-international-power-adapter-with-a-charger/375951 "2006-10-10T17:45:00Z")\ **Posts on this page:** 5\ **Page:** 2
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [October 11, 2006, 7:15pm UTC](https://boards.straightdope.com/t/can-you-use-an-international-power-adapter-with-a-charger/375951/21 "2006-10-11T19:15:49Z")
[QUOTE=Chronos] Don’t ask me what ohmic-only devices anyone would ever bring on vacation with them [/QUOTE] Curling irons, travel irons, hair dryers; that sort of thing. Yes, there’s a small reactive component to all of these, but by far the biggest component is resistive. The notice should read “PRIMARILY OHMIC LOADS”, but you don’t want to confuse people who have no background in electronics. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [October 11, 2006, 7:22pm UTC](https://boards.straightdope.com/t/can-you-use-an-international-power-adapter-with-a-charger/375951/22 "2006-10-11T19:22:59Z")
[QUOTE=Chronos] “NOT FOR USE WITH BATTERY CHARGERS. OHMIC LOADS ONLY”. Don’t ask me what ohmic-only devices anyone would ever bring on vacation with them. [/QUOTE] Hair drier, curling iron, touch up iron for clothes…and a soldering iron in my case. These converters use a phase control triac to switch the current on and off, so it is only on half time, which **averages** to half voltage. They put out a waveform that is a sine wave at 90-180 and 270-360 degrees and zero elsewhere. The problem is that nearly any charger captures the **peak** voltage, not the average voltage. The peaks are at 90 and 270 degrees, so a phase control circuit does not halve the peak voltage applied. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [October 11, 2006, 7:39pm UTC](https://boards.straightdope.com/t/can-you-use-an-international-power-adapter-with-a-charger/375951/23 "2006-10-11T19:39:56Z")
Isn’t the motor in a hair drier a non-neglible inductive load, though? I’ll grant curling irons and travel irons; I didn’t think of those just because nobody I’ve ever travelled with uses them. Still, I can think of a lot more non-ohmic loads than ohmic that a person would travel with (electric shavers, still and video cameras, laptops, music devices, etc.). ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [October 12, 2006, 4:56am UTC](https://boards.straightdope.com/t/can-you-use-an-international-power-adapter-with-a-charger/375951/24 "2006-10-12T04:56:15Z")
[QUOTE=Chronos] Isn’t the motor in a hair drier a non-neglible inductive load, though? [/QUOTE] Not really. These all use some kind of low-voltage motor, typically between 6-12 V. Hair dryers usually use the heating element as a dropping resistor to supply the motor with whatever voltage it needs, while shavers and other things with very small motors use various techniques. In any case, low-voltage means fewer turns in the windings, which (along with a small core) means a small inductance. At 50 or 60 Hz, these motor windings generally have a much greater DC resistance than they do inductive reactance. ---
**Author:** ![Zsofia](https://avatars.discourse-cdn.com/v4/letter/z/7bcc69/32.png) [@Zsofia](https://boards.straightdope.com/u/Zsofia)\ **Post date:** [October 13, 2006, 12:52am UTC](https://boards.straightdope.com/t/can-you-use-an-international-power-adapter-with-a-charger/375951/25 "2006-10-13T00:52:19Z")
FYI, had to go to Radio Shack. The ones at Best Buy said it was for heat-producing appliances only. [Previous page](https://boards.straightdope.com/t/can-you-use-an-international-power-adapter-with-a-charger/375951.md?page=1)