Yes, that power supply will work on the 7.5,9v or 12v settings. Based on the diagram on the supply, It looks like you can adjust the polarity of the barrel jack plug. You will want to make sure that you have the center of the plug set as + (positive).
Thank you so much for your reply Dan.Do you think that is it better to use a higher voltage (9V) or is 7.5V sufficient?
Furthermore,is 1500 mA safe like power value?Lastly, this is the plug...I think that it's the right one!