Except as provided in Sections 65 and 66, no obligations shall be issued to pay current expenses, but the council may issue and sell obligations for any other municipal purpose in accordance with law and within the limitations prescribed by law. Except in the case of obligations for which an election is not required by this charter or by state law, no such obligations shall be issued and sold without the approval of the majority of the electors of the city voting on the question at a general or special election.