Hello,

I searched a lot for a circuit of a sensor light but didn't find any. I know that these lamps senses motion with an ultrasonic motion detector with sensing range of several meters, but for an ultrasonic motion detector an ultrasonic transmitter transducer and a receiver transducer should be used, right? I saw somewhere pictures for a sensor light showing only one transducer .
Anyway, their ultrasonic motion detector is good and practical for some projects, and I'm searching such a circuit as a part of a bigger project.

Regards,
Hazim

 

Do you mean one of these?
http://en.wikipedia.org/wiki/PIR_sensor

Normally used to turn on annoying motion sensitive floodlights outside peoples houses.

 

Hi,
There are lots of types of motion sensors used in lamp circuits. I believe that an I.R. (infrared) motion sensor is more common than an ultrasonic type. There are lots of ways you can use these. For an I.R. sensor, you only need the one sensor and there is no need for a separate transmitter and receiver. It simply detects the presence of a person (or even a dog) by the body heat given off by the person and these can be quite sensitive or they can be adjusted so that small cats and dogs won't set off the sensor. If you were thinking of using an ultrasonic type with a separate transmitter and receiver, I would say you would likely be better off using an optical beam with an LED transmitter and a photodetector receiver. If you choose an optical frequency in the I.R. or possibly U.V. regions, it will be invisible to anyone walking across the beam.
Good luck.
Regards,
Kamran Kazem

 

Yes, that was a PIR sensor.. and it functions as kazem said. I googled "PIR sensor" and found what I was looking for. Thanks for you

Regards,
Hazim