General question - Mortgage levels for second investment property

I have a general question based upon a potential situation.  

I am looking to possibly buy a personal residence, and then buy investment property afterwards.  Holding both properties.  My question is how much do banks/financial institutions typically loan for the second investment house?  I want to know how much I could afford for the second house, because that will determine how much I actually spend on the personal residence property.  Please let me know any thoughts.  Thanks everyone!