| General > General Technical Chat |
| Cheap, electronic US-to-EU mains converters |
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| wraper:
You need autotransformer for (usually high power) devices which require 230V like Ktettle, coffee machine and similar. Be aware that power that US sockets are rated for way less power than in EU. Devices that use SMPS most likely can work from 120V to begin with. Like phone chargers, PC/laptop PSU, TV and similar. |
| soldar:
--- Quote from: tom66 on November 03, 2023, 10:50:15 am ---I've seen those cheap power converter (for 240V to 120V) before, and torn one apart -- it had a single diode in it. Which resulted in 240V power becoming half-wave rectified, and in the mind of the engineers who designed it in China, that was 120V. In fact, even for a heating element, it's still twice the rated power because V2 * I. Using one of these power supplies destroyed a nice American coffee maker that a friend had imported over. A £20 purchase on Amazon killed a $600 espresso machine. For the other way around (120V -> 240V), I suspect they are just autotransformers, so are *probably* ok to use, but unlikely to withstand the 2kW rating they claim unless they are quite substantial. --- End quote --- I have a 30 year old Radio Shack Archer 273-1404 triac converter which allows the use of 120V heating appliances with 220 V. It is basically a dimmer type control but what is interesting is the trigger circuit which is not the usual delay type but is triggered by a capacitor and the wave falling from the top. So it is essentially impossible to fire too soon because the wave has to fall a certain amount for it to trigger. It is quite clever. |
| NiHaoMike:
For the case of converting 120V to 240V, one could voltage doubler rectify the 120V, then generate a 120V modified sine which is 180 degrees out of phase so it adds to the original 120V. The resulting waveform quality would be in between pure sine and modified sine. |
| rstofer:
If you just buy replacement gadgets (coffee maker, etc) you might consider donating them to one of the larger charities (Salvation Army, Good Will, etc) and see if the tax deduction helps. Or advertise them in the ex-pat community, some newcomer will need them for the same reason. |
| bdunham7:
--- Quote from: TheUnnamedNewbie on November 03, 2023, 09:38:40 am --- To my surprise, you can find 20-30 USD adapters that claim 2 kW output power - much cheaper than the 150 bucks I remember for a single 1 kW transformer, and it's the size of a simple power brick! --- End quote --- Do you have a link to one of these devices? I can't imagine what would be worth all the trouble of doing this adapting--you're not going to get enough power to run your 3kW kettle unless you tap directly into a panel or unplug a clothes dryer. Most other devices just need a connective adapter and will work on 120VAC. Those that don't can be replaced cheaply. If you really did have a need to run anything on 240VAC, just get an actual transformer--they aren't that terribly expensive in a reasonable capacity (not 2kW). |
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