Motion detector with impulse function

Conventional motion detectors switch the connected consumer directly. For more complex installations, a pulse function for the motion detector may be necessary. We have summarized below what it has to do with an impulse function for motion detectors.

The connection of a conventional motion detector

A conventional connection of the motion detector is the supply of the three lines N, L and PE to the motion detector and then on to the consumer, such as a lamp. It is also possible to integrate a switch in front of the motion detector. Even two motion detectors can be connected in series.

Disadvantages of this circuit diagram

However, under this connection requirement, the two switching times of the two motion detectors are added if living beings or objects fall into the monitoring areas of both detectors. In addition to this effect, there are some other circuits that make a conventional motion detector impossible.

Special challenge with the example of a stairwell lighting circuit

This includes, for example, a staircase lighting installation with a timer unit. In order to be able to address such a device, an impulse function is necessary. As a result, the said time control unit knows that the staircase light is to be triggered even without actuating a switch. Also, the switching time when using multiple motion detectors in the stairwell can not add up.


In order to be able to make such a circuit, however, some prerequisites have to be checked in advance or presupposed:

  • Impulse function of the motion detector must be present
  • Timer should have a connection for motion detector (can respond to impulse function)

Wiring diagram for pulse function

Connecting the motion detector then takes place like a normal installation. Only that the outgoing line L2, "output" or "arrow" for output is not connected to the consumer, in this case a lamp. Instead, L2 is then connected to the motion detector with the corresponding input on the time switch.

Pulse function of motion detectors in general

Meanwhile, the impulse function of the motion detector is finding more and more fields of application. For example, the Smart Home offers numerous possibilities in which the impulse function considerably simplifies installation and opens up new possibilities. The instruction manuals show exactly how impulse functions can be used for other requirements.

Tips & Tricks

When selecting a detector, also pay attention to the respective mode of operation of the different motion detectors. Here, especially when recognizing a movement, there are clear differences due to different technologies. In addition, each motion detector should match the power consumption of the consumer. Also LED bulbs are to be considered separately.

Video Board: Node-RED Pt.3: Trigger and Events: All nodes. Motion Lighting and Actionable Notifications.