Variac

[ppppenguin]

However, the spec looks a bit odd, because it states

• 2.75 AMP VARIAC
• Input 283v max 47hz
• 0 to 240v output @ 2.75amp

That doesn’t make sense – why would a variac operate on such a precise non-standard input voltage such as 283 Volts at 47 Hz, and if it did, why would it only provide 240V output? They’re questions that would need to be answered by the seller of course, (who has seven available)

The spec needs to be read differently. 283V is the maximum input voltage, presumably using the whole winding, which isn't the way you usually connect a variac. You normally have a tap for 230V-ish input so the output can go up to 260V or 270V. 47Hz is simply a minimum frequency. If you go any lower the magnetising current will be too high. 50Hz or 60Hz will be no problem at all.