Abstract: A battery charging circuit comprises a first circuit provided for interrupting the power supplied to a load to rapid charge a secondary battery with an external power source, and a second circuit provided for enabling the power supplied to the load and charging the secondary battery with a trickle charge. A control circuit is provided for selectively activating the first circuit and the second circuit.

Abstract: An electronic cash register includes a melody generation system for generating a melody for as long as the cash box is open. Information corresponding to a plurality of melodies is stored in the melody generation system for changing the melody in accordance with a certain condition. In a preferred form, a first melody is generated when the current time has not yet reached a preselected time, and a second melody is generated when the current time has already reached the preselected time. In another preferred form, the melody is changed when the clerk who handles the electronic cash register changes.

Abstract: Contact patterns are formed on a transparent substrate to introduce information or a command into a system. A display means, responsive to the opening and closing of the contact patterns, is installed behind the transparent substrate, thereby indicating a switching condition of a switching means associated with the contact patterns.

Abstract: A light emitting diode has a metal casing connected to the cathode electrode thereof to protect the light emitting diode from the ambient conditions. Detector circuitry is provided for detecting touch operation by an operator to the metal casing of the light emitting diode. A driver is responsive to the output of the detector circuitry for enabling the light emitting diode when the touch operation is effected to the metal casing of the light emitting diode.