My father has a wave generator that runs on either a 9V battery, PP3 type or DC through a 9V charger rated at between 500mA and 1000mA. He's lost the original charger and i'm having the dickens of a job locating a similar one. The original charger was 110/120V US and was used in europe with a transformer. Am i being stupid (don't answer

) to think that as long as the european charger is 9V and between 500-1000mA that i could just get him that as a replacement ?
Also, because the device is rated at 500-1000mA, what would be the appropriate or best fit in terms of mA ? Any helpful replies much appreciated.
SHJ