Panasonic PM-65 amplifier built-in/U-shaped micro photoelectric sensor compact/connector built-in type models are standardly equipped with the following protection circuits in their compact bodies. These protection circuits minimize the possibility of sensor malfunctions caused by erroneous wiring. The beam emitting and receiving sections are 0.5 mm 0.02 in thinner than those on our conventional models while their external dimensions are the same. As a result, the distance between the beam emitting point and receiving point increased by 1 mm 0.039 in. The wider distance means less possibility of collision between the sensing section and sensing object. The upper-limit and lower-limit positions of beam can be visually confirmed from the front and back sides of the sensor unit. This allows easy adjustment of the position of sensing object. The large operation indicator (orange) lights up when the beam enters. The indicator is easy to see from above and from the sides. The sections where stress concentrates, such as the connecting section of the cable and internal circuit, are covered with a resin. This helps prevent malfunctions caused by vibrations and impacts. The connector connection type eliminates the extra work of soldering and insulation processing. In addition, the connector used is a commercially-available multipurpose connector which is also currently used by the DP-100 series of digital pressure sensors.