Abstract: Temperature comparison circuits which utilize two thermistors which are initially set up in a balanced bridge using NPN transistors and resistors. As temperature differences between the thermistors cause the bridge to become unbalanced, there is a current flow in which the voltage varies in magnitude and direction. The circuits are attached to electrical equipment which is sensitive to changes in magnitude and direction of voltage. The circuits find uses in controlling refrigeration systems, controlling heating and cooling systems, and performing diagnostic tests on mammals or devices which contain temperature differences between two separate points. The circuits may be used in cooperation with an expansion valve which is located in the tubing of a refrigeration system. The tubing is non-magnetic. There is a fixed magnetizable plate having a central orifice.

Abstract: A security device for a bill changer that greatly reduces the risk of the coinage within the changer from being robbed. The security device includes a support having a bill insertion slot therethrough. The support is adapted to be securely attached to a front surface of a bill reader with the insertion slot aligned with a corresponding slot of the bill reader. A moveable blade is mounted on the support and detaches foreign objects extending from an inserted bill. An actuator member, preferably comprising two solenoids, is connected to the blade for moving the blade across the insertion slot in response to validation of an inserted bill by the bill reader to detach any foreign objects therefrom.

Abstract: A security device for a bill changer that greatly reduces the risk of the coinage within the changer from being robbed. The security device includes a support having a bill insertion slot therethrough. The support is adapted to be securely attached to a front surface of a bill reader with the insertion slot aligned with a corresponding slot of the bill reader. A moveable blade is mounted on the support and detaches foreign objects extending from an inserted bill. An actuator member, preferably comprising two solenoids, is connected to the blade for moving the blade across the insertion slot in response to validation of an inserted bill by the bill reader to detach any foreign objects therefrom.