Abstract: A differential DC/RF bridge-configured flowcell particle detector includes a flowcell and an adjustable circuit model of the flowcell, which are differentially coupled through output amplifier circuits and galvanically isolated from sources of signal degradation. The output of the difference amplifier is coupled to a DC/RF discriminator and associated downstream processing circuitry. Respective amplitude and phase outputs of the DC/RF discriminator are used to control amplitude and phase adjustment circuits of the adjustable circuit model, so as to automatically track amplitude and phase variations in the non-linear behavior of the flowcell, to mirror the characteristic impedance of the flowcell, thereby making the bridge insensitive to variations in the flowcell.

Abstract: A power supply apparatus which includes at least one switching power supply disposed in a chassis connected to earth ground and at least one D.C. to D.C. converter whose inputs float with respect to system ground. To reduce transmission of high-frequency electrical switching energy from the switching power supply to the load, the invention contemplates a tuned reactive circuit connected between the system ground and the earth ground. Electrical switching energy is shunted to earth ground by way of bypass capacitors located at various stages of the power supply apparatus. A further aspect of the apparatus contemplates the interposition of low-pass filters between the switching power supply and one or more D.C. to D.C. converters connected to the power supply and/or between the D.C. to D.C. converters and their respective loads to effectively eliminate radiated electromagnetic energy.