In the pix above, notice both the plug and receptacle. Both are 20A devices. Both have one blade 'horizontal' and one blade 'vertical'. The positioning of the blades is reversed. This is the type of voltage/current rating distinctions Michaeltoc was describing. Notice the
230v plug will not mate with the
115 receptacle(blade positioning is reversed). Also a
115v plug will not mate with a
230v receptacle.
However a
115v 15A plug will fit into that
115v 20A receptacle(blades are both 'vertical'). The reverse is not true!
A
230v 15A plug has both blades 'horizontal' and will mate with the
230v receptacle. The reverse is not true!
20A receptacles are designed to accept
either 20A or 15A plugs.
15A devices are easier to find and are much less expensive.
Regarding codes, that is the reason these are called cheater cords. However today many appliances are 'multi-voltage compatible' and are not adequately addressed in the 'code'. Some use plugable cords that have different plugs in the input end. My computer power supply also works on 12v DC and the power cord has 5 pins on the 'brick' end.
So: Make a cheater cord with a 115v 15a inline receptacle and a 230v 15A plug. #14 is large enough. Keep it short(6" to a foot).
All voltage numbers mentioned above(115v, 230v) may be 120/240 on the devices you find. Actual voltages in my area are typically 125/250v measured at the source.
If the word receptacle bothers you substitute 'outlet'.

More descriptive would be female.
P.S. See post #4 for wiring 'instructions'.
Paul: A european 'plug' converter will only work if you install a european receptacle in your USA house.