Long time reader (Well, I've spent hours reading posts over the past few days!) but first time poster. I have a question about PIR's and cable length.
Background : I am building a home monitoring system. It is to monitor motion in 3 areas outside my house. Also to monitor temperature both inside and out and control a panning servo with a small external camera to snap to locations when motion is detected. The system is to reside inside my house on my desk, with the possibility of a small LCD screen to display motion detected alerts along with LED's.
Questions :
PIRs - There are plenty of PIRs that can be purchased - but someone suggested to be the cable length could only go to about 1-2M away from the arduino board. This is obviously a problem as I want the board to be on my desk. How should I go about this? Someone has suggested buying external PIR's that are used commercially. How will they interface with the board? Are they the same setup? (3 wire +/-/SIG?) Will the board be able to power 2 or 3 of them at the same time? Should I be looking into another form of PIR?
Panning Servo - I already have a small security camera out the front which I would like to mount on a servo located near 2 of the PIR's. When motion is detected, it should pan to the area so I can have a look. Ideal setup, it snaps a photo and emails it to me. But that's a long way off. What servo should I look into for something like this?
Admins : I hope this was the right area to post this.
Many thanks for your help guys, I'm really looking forward to getting this project off the ground.
But I would think that many wired sensors intended for home security would handle the cable lengths you neeed.
I think I have seen one or two discussions here recently about servos for pan and tilt camera mounts. The right servo for you will depend on the weight of your camera and be some compromise on speed (how fast it moves into position) and price. How much does your camera weigh and how fast does it need to move, and is it just panning (with fixed tilt) ?
Thanks for the reply.
1/ The wired PIR's - so would you suggest a commercial PIR that requires separate 12V, rather than just buying the small sensors? Ideally i would LOVE to buy just the small chipboard ones, put them in a water tight black box and mount them, but the cable length would need to be about 10-15M. I'm guessing that is probably not possible?
2/ I would love pan AND tilt, but it's probably not a requirement. The camera is only very small, the size of a webcam. Speed doesn't need to be anything super fast, but when motion is detected I would like it to pan to the 'zone' fast enough to see what triggered the event. I only want it to have 3 zones. Left, right, middle. PIR's will monitor the left and right zones and the camera will have a default position of middle. So if any movement is detected to the left or right, the camera turns to that 'zone'.
Then pan servo idea can wait, it's the PIR's and cable solution I want to get solved so I can actually start building the system.
I would think that it would cost more to put together a wired DIY sensor with a box and other components then something off the shelf from ebay or another online retailer. A search through some of the sites that cover diy home security systems should provide the answer to your questions about wiring and power.
It might cost a little more - but where's the fun in that? It's more of a project for me to learn about electronic components than being a cost effective solution. The only thing stopping me is the wiring length... once I find out if I can run say a 10M cable from the controller to the PIR, I'm good to go.
I want everything to be all controlled out of the one box. A box on my desk with LCD and LED's to indicate motion, the LCD to also display temp's when requested, and the LCD to display system messages etc. From there, expanding is easy and fun.
The power requirements are tiny so should be no problem running them off the board, why not give it a try.
If learning about electronic components is a goal, at least consider the approach of re-purposing off the shelf products to get access to the components already mounted in a box waiting for you to figure out how to interface it. It's not the same as building something from scratch, but IMO one can learn a lot by opening up a commercial product and building your own interface.
And it can be just as much (if not more) fun
I live in Australia so radioshack is a little out of the way, but thanks. We have a few places I can order them from here.
My concern with cable length is someone mentioned resistance is built up over unshielded cable - so if I have a 15m cable running to one of these sensors it won't have enough power left by the time it gets there. Likewise with sending information back to the board.
Thanks for the advice - but I think i'll build it all from scratch, it just seems more fun to me.
If you can't find a local supplier, futurlec ships to Australia and although delivery can be slow, their prices are good.
The sensors use so little power I am surprised that resistance of the power line is an issue. I would think that the TTL data line is more likely to be an issue over long distances. But there are many solutions for that issue.
Excellent, thanks very much for your help. I've just placed an order (from 3 different sites!) for an arduino, 2x PIR's, 2x Temp sensors. I have a million jumper cables lying around which I can use to test everything.
Out of curiosity, if I do run into troubles with the data line - what are the solutions you mentioned?
Search terms such as : TTL line driver should turn up a bunch stuff that you could use. But because your data rate is so low I would not think you need anything exotic.
It's more of a project for me to learn about electronic components than being a cost effective solution. The only thing stopping me is the wiring length... once I find out if I can run say a 10M cable from the controller to the PIR, I'm good to go.