Abstract: A solvent delivery system (10) has first and second pistons (92, 94) and cylinders (58, 68) connected to first and second cams (110, 112). The cams (110, 112) each have a ramped portion (150, 162) and an abrupt step (152, 164). The first cylinder (58) is connected to solenoid valves (44, 46, 48) to fill the first cylinder with solvent components during movement of cam follower (104) along ramped portion (150) of the first cam (110). Spring (140) urges the first piston (92) forward into first cylinder (58). Movement of the cam follower (104) over the step (152) of the cam (110) moves the piston (92) forward abruptly to force the solvent components from cylinder (58) into second cylinder (68). Spring (178) urges piston (94) back in cylinder (68). The second cam (112) is reversed relative to first cam (110). Movement of cam follower (106) over abrupt step (164) of second cam (112) moves second piston (94) back abruptly in cylinder (68) to receive and mix the solvent components in the cylinder (68).

Abstract: Electrocardiograph apparatus capable of discerning the H-wave in the P-Q interval of an ECG signal comprises a charge transfer device delaying the ECG signal and a signal averager circuit triggerable by an R-wave peak detector for summing a plurality of the delayed ECG signals in time-locked relationship to the detected R-wave peak.