The corporation may issue bonds at any time and from time to time as the board may determine to be most advantageous for the purpose of paying the purchase price of and all expenses incurred in connection with the acquisition of any properties or other assets of the corporation and for the purpose of furnishing adequate working capital for the corporation. Such bonds shall be revenue bonds payable solely out of the revenues derived from the operation of all or any part of any utility owned by the corporation as may be provided at the time of the authorization of such bonds. All bonds shall be signed by such officer or officers as the board may direct, but the facsimile of any signature may be impressed on any interest coupons in lieu of the original signature. The bonds shall be in such form, whether registered or bearer, shall be in such denominations, shall bear such dates and have such maturities not exceeding 40 years from their respective dates, may be in one or more series, shall contain such provisions not inconsistent herewith, shall bear such rate or rates of interest payable and evidenced in such manner, shall be payable at such place or places and shall be subject to such terms of redemption with or without premium, all as may be provided by resolution of the board. The bonds shall be sold at public sale in such manner and at such price or prices and at such time or times and after such notice or notices as may be determined by the board to be most advantageous, provided that the interest cost to maturity of the money received for any issue of bonds so sold shall not exceed six percent per annum compounded semiannually; provided further, that the provisions of this sentence shall not apply to bonds payable within less than one year and limited to an aggregate principal amount not exceeding $5,000.00, which may be sold at private sale at such times and in such manner as may be determined by the board to be most advantageous. Any bonds issued and any obligations incurred by the corporation may be refunded either by sale of refunding bonds or by exchange of such refunding bonds for a like principal amount of the bonds and obligations proposed to be refunded thereby. Any such refunding may be effected either before or after the maturity of the bonds or obligations proposed to be refunded thereby. Pending the preparation or execution of definitive bonds, interim receipts or temporary bonds may be delivered to the purchaser thereof.