You can surely buy one on eBay, yes.
UK is 220v
No, you cannot directly convert a 120V household outlet to supply 220V 3-phase power for a machine. You would need a transformer to step up the voltage and a suitable 3-phase power source to provide the required power for the machine. It is recommended to consult with a licensed electrician to ensure proper installation and safety compliance.
120V appliance will not work on 220V. Use an instrument transformer or voltage regulator to adjust the high voltage to the desired level.
You don't, at least, not legally.
Using a 120V heat element with a 220V supply is not advisable, even with a rheostat, as it could damage the element or create a fire hazard. A rheostat can reduce voltage, but it may not provide consistent or safe operation under varying loads. It's best to use a heat element rated for the voltage of your supply to ensure safety and efficiency. For a 220V supply, look for a compatible 220V heat element instead.
No, 120 v is not enough.
Brazil has a nominal voltage of 220/380V.
If you mean - can you run a 220v device on 120v where the 220v device needs that level of voltage to operate correctly then the answer is no. Even disregarding the frequency difference which some devices aren't affected by, the voltage difference is too great. Some devices these days, such as phone chargers, laptop power supply units etc will run happily on a voltage range from 100v up to 240v (read the label first) but they are the exception. The question is somewhat ambiguous and needs more information.
No, connecting a 120V device directly to a 220V power source is not safe and can cause damage to the device, create a fire hazard, or result in electrical shock. Devices are designed to operate at specific voltage levels, and exceeding that can lead to catastrophic failures. If you need to use a 120V device in a 220V environment, consider using a step-down transformer to safely convert the voltage.
This type of a transformer is known as a step up transformer.
To rewire a 220V lamp for 120V, you will need to replace the existing 220V bulb with a 120V bulb that is compatible with the lamp's socket. Next, you will need to install a 120V compatible power cord that matches the voltage requirements of the lamp. It's important to refer to the lamp's manual or consult with a professional electrician to ensure the rewiring is done correctly and safely.
No, a device designed for 110v will not work on 220v without a voltage converter.