Abstract: An RF shielded and electrically insulated circuit board structure comprises a first layer of shrink wrap tubing wrapped on a circuit board substrate, and a layer of an electrically conductive RF shielding material on the tubing. A second layer of shrink wrap tubing retains the electrically conductive material to the circuit board. Edge portions of the electrically conductive layer and heat shrink tubing are folded inward to prevent RF energy from the circuit board from leaking from the edges of the structure. The structure is made by wrapping a first heat shrink tubing on the circuit board to insulate and seal any wiring patterns and components thereon and shrinking the tubing by applying heat. The electrically conductive layer is located on the heat shrink tubing, and the second heat shrink tubing is wrapped on the electrically conductive layer and first tubing.

Abstract: A heat shrinkable strain relief device protects electrical wires passing through an aperture in a partition and secures the wires to the partition. The strain relief includes a first heat shrunk tube overlying the wires and having a diameter that is no larger than the diameter of the aperture. A second heat shrunk tube overlying a portion of the first heat shrunk tube has an outer diameter greater than that of the aperture. The strain relief is located in the partition with only a length of first heat shrunk tube that extends outward from the second heat shrunk tube passing through the aperture. A third optional heat shrunk tube positioned on the first heat shrunk tube is spaced apart from the second tube by a distance approximately equal to the thickness of the partition. The strain relief device is formed by locating lenghts of heat shrinkable tubing in predetermined positions on the wires, and applying heat.

Abstract: A portable tester determines an operating condition of coin relays by sensing a duration of a time period between flux conditions generated thereby. The device does not require electrical circuit connection to the relay and is thus a non-invasive testing apparatus. An annunciator provides audible and visual indications to service personnel to indicate whether the detected duration is too short, requiring one form of adjustment, too long, requiring a second form of adjustment, or within a specified range therefor, requiring no adjustment.

Abstract: A temperature sensor located at a region being monitored controls an output switch that in one position when ambient temperature is below a predetermined temperature applies current to only a first loop circuit and in another position when ambient temperature is at or above the predetermined temperature applies current to only a second loop circuit. Currents in the first and second loop circuits are measured by ferrods to determine whether an over-temperature condition at the region monitored has taken place. An alarm circuit connected to outputs of the ferrods generates an alarm signal in response to a negative transaction of current in the first loop circuit or a positive transition of current in the second loop circuit. A failure in either loop circuit accordingly is insufficient to disable the system. A solid state timer periodically opens the second loop circuit to repeat the alarm signal when the second loop circuit is closed until corrective action is taken.

Abstract: An electronic circuit board, together with the components, circuits, and wiring patterns thereon, is encapsulated by a single heat-shrink tubing layer, or the like for insulation from environmental factors. A method for the encapsulation is disclosed, as well as products incorporating the inventive approach.