The motion sensor switch circuit can automatically turn on a water sprinkler but you can easily use it as a motion sensor light switch or motion activated alarm too. Before beginning the construction ...

Therefore, the 9V signal is then lowered once more using a voltage divider circuit. When the PIR sensor is triggered, it activates the timer circuit. The timer circuit is driven by a 555 timer.

If Philips adds other sensors, they’d stay focused on lighting The motion sensors will sell for $39.95, with up to 12 supported on a single Hue bridge. They’ll go on sale in October.