motion sensor timing

[slightlyagitatedwookie]

I want use a standard outdoor motion sensor to turn on a 12V power supply for only a very short time. The units I have seen are adjustable so the lights come on for 5-15 minutes when motion is detected. How do I change it so it only stays on for a range of 1-10 seconds?

[Chris Smith]

Trace the multi position slide switch down [or pot] inside the unit and change the value for one or more of the resistors [or change the pot] of the multi position switch with lower value resistors. You need to experiment to find the value that suits your needs. You can count the timing positions on a slide switch and check the values for the individual resistors and calculate roughly the value needed to replace a resistor for your timing cycle. If 5k resistor is equal to 15 minutes, roughly speaking it could equate 1k per three minutes. If this math works for the other positions as well, you can calculate the timing down to with in a few seconds using straight math.

[slightlyagitatedwookie]

Thanks, Chris<p>I'll try that out
Heath

[josmith]

Or just put it into test mode

[slightlyagitatedwookie]

Thanks that sounds even simpler if the test mode works out to be the time frame I'm looking for.<p>On a similiar note, I want to hide this sensor behind an Aluminum vent with angled slats. Will the sensor still work? I only need a range of 5-10 ft.

[Chris Smith]

What ever your eyes would see behind that vent, the sensor can also see. Dont hide any sensor behind glass or plastic however. The vents will limit and obstruct the area and sensitivity some what. If you have heat or cold running through that vent, there is a great chance it will set off the sensor. Never place a IR sensor near or at a heater vent.

[slightlyagitatedwookie]

Thanks Chris,<p>I had heard that metals affect the sensing ability. I didn't think it would be an issue since it was detecteing change in heat. Hot air will not be an issue. The sensor is going into a replica of R2-D2 in the vents on the chest area to trigger the head to rotate back and forth with a windshield wiper motor. So the vents are purely decorative.<p>Heath

[Chris Smith]

Its not the metal that effects the unit, its the variances in heat absorbed in metals [IR light/heat] in diferent spots refered to as "hot spots". This throws off the sensor if these changes are drastic or changing through time too quickly.