I have recently had a MkI charging base fail, and would like to know if the charging logic is part of the charger or part of the phone.  MkI base stations are difficult to source now but on checking in my "man drawer" I have a 5.6v regulated adapter (from a mobile phone or something similar I expect).  I have verified it's output, but before I risk using it I would like to confirm that it's the phone that decides when it's fully charged and not the charger.

Can anybody help? 

Well - the charging logic is located in the handset and using the described power adapter may work, but I would never recommend using a "non-authorized" power adapter.