Uses a reflective infra-red sensor for counting drops. The sensor contains a high-power infra-red emitting diode and a photo-transistor. A background correction circuit removes any interference due to ambient sunlight at the detector. The Drop Counter is supplied with a DIN connector and requires 5V power, and connects directly to any Pod Port of a PowerLab. The unit is light weight and can be easily attached to a clamp and retort stand. The sensor is impervious to ambient light and the unit is chemically resistant. The counter can be used in titration experiments using a burette as well as measuring physiological fluids such as urine and gastric juices collected from rodents.