I have a project I'm working on and kind of running into a wall on figuring it out. Historically speaking, I do not have a lot of electronics background so please bear with me. I have a keypad mounted in a housing. This keypad is unlit, making it very difficult for others to see the numbers when it's still dark outside. What I'd like to do is illuminate it with a small light. Possibly LED, or? The other thing I'd like to use is a small motion detector so that it's not lit all the time (not a good neighborhood, not trying to draw attention to it).

Within the unit I have 24VDC. I also have plenty of room inside to mount a small transformer if needed. I need something that can put up with the elements as it is outside (the light, that is. Any other components would go in the cabinet). Any chance one of you gurus would like to toss some help my way? Thank you

 

Another option would be to just illuminate the keypad for an interval of time once any of the buttons are pressed. The 1st button press is "ignored" as far as the key sequence goes.

This strategy requires the user to be able to find the keypad, which is easy for a user that knows where it is, and avoids having it light up for just a random passerby.

 

TONS of examples/tutorials on the internet for a simple motion sensor..
http://www.learningaboutelectronics.com/Articles/Motion-detector-circuit.php

 

Thank you for the replies. I need to source the proper light, a simple LED won't provide enough light. After looking at the link you provided, the motion detection side will be simple.

 

Thank you for the replies. I need to source the proper light, a simple LED won't provide enough light. After looking at the link you provided, the motion detection side will be simple.

For simple keypad illumination? Sure it will..
you can put a few in series if you need a bit more.. but a 20mA white LED should be more than sufficient for keypad illumination IMO..

 

Thank you for the replies. I need to source the proper light, a simple LED won't provide enough light.

Have you seen how bright LEDs are these days?

 

Apparently, I stand corrected! Like I said before guys, I'm not doing this kind of stuff often so I'm not all that knowledgeable. So it looks like I can get a PIR sensor, 1 or a couple of LED's, and whatever resistor I'll need and be all set? I have 24vdc in the keypad, I'll have to knock it down to 9 or so. Any idea how long a 9v. battery would last roughly if I went the battery route?

 

Apparently, I stand corrected! Like I said before guys, I'm not doing this kind of stuff often so I'm not all that knowledgeable. So it looks like I can get a PIR sensor, 1 or a couple of LED's, and whatever resistor I'll need and be all set? I have 24vdc in the keypad, I'll have to knock it down to 9 or so. Any idea how long a 9v. battery would last roughly if I went the battery route?

avoid batteries if you have a power source already.. Add a 12V regulator circuit off your 24VDC supply and call it a day.. No worries about replacing batteries.