In an SDRAM chip, two signal generation circuits are provided corresponding to two test circuits arranged at either ends of a rectangular semiconductor substrate. Each signal generation circuit is provided in the proximity of corresponding test circuit. Hence, a signal line for test signal can be reduced and smaller chip area can be achieved compared with the conventional case where one signal generation circuit is provided at a center of the semiconductor substrate and a test signal is supplied to two test circuits from the signal generation circuit.

An electrical generator in a coin mechanism supplies enough current to operate an electronic device or an electromagnetic device such as a solenoid, by providing a stator mounted about a rotor and driven by a spring-loaded drive wheel. The drive wheel rotates with the coin mechanism up to a release position, loading the spring. At the release position the drive wheel is released and snaps back to the rest position, driving the rotor and causing the rotor to rotate rapidly within the stator, generating an electric pulse. The electrical signal can be used to pulse a counter, electronic tag or other tracking device, and to recharge a small battery which may be provided as a backup or auxiliary power source. In one embodiment the invention further provides a means for determining whether a deposited coin is composed of metal or form a non-conductive material such as plastic or cardboard.