Abstract: The invention relates to a circuit arrangement for operation of a relay which provides a switching-on current for the field coil of the relay and subsequently, after a predetermined time, a holding current. In order that any possible discrepancies in the parameters of the relay from their nominal values have no negative influence and need not be taken into account when designing the circuit, and in order that the circuit arrangement can be used with operating voltages of different magnitude, at least one constant current source supplies the relay switching-on current and the relay holding current.

Abstract: This is a single lumen balloon catheter having an infusion section distal of that balloon for infusing liquids into the bloodstream. In general, the infusion section has a plurality of holes in the wall of the section proximal of the tip so to allow infusion of that selected material. Depending upon the variation of the invention selected, the infusion section may have valve seats at either or both ends of that infusion section. The device may include a core wire for assistance in controlling the infusion of liquids through the distal sections orifices. The core wire, in most variations of the invention, may also be used as a guidewire for introducing the catheter with its attendant balloon to a suitable site. The single lumen is used both for inflation of the balloon and infusion of the treatment or diagnostic material. The balloon itself, depending upon the use to which the catheter is to be placed, may be either a compliant balloon or one having a predetermined fixed diameter.