I recently added this project to my blog, if you don't want to wade through all the how to 'ness then this summary might be better to read.
I made it as part of the Gift Exchange.
It works by sending out a modulated infrared signal. The detector then senses any of the reflected signal, this is how it knows if anyone has passed by.
The main board contains a pickaxe chip. There is a mode select button which allows you to cycle through the different detection methods and alerts.
It runs off of 3 x AG-13 button cells and can sense up to 15cm+ in good conditions.
For a demo watch this video.
I also made a couple of instruction manuals which are attached.
Instructables reduces the image quality of uploads so I've included a PDF with all the diagram illustrations at high res.
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Signing UpStep 1: Materials
I've included links to techsupplies.co.uk so you can see what the pieces look like, as well as places you are likely to find the component.
Components: Likely places to find them:
- Picaxe 08M chip
- Perf / strip board
- IR sensor 38kHz
- 2mm red LED
- 5mm IR LED Any Remote control
- Piezo transducer Anything that makes a beep noise
- 6mm tactile switch Anything that clicks when you press it
- PCB mount slide switch
- Resistors with rough values of 32k, 10k, 1k, 300, 180 Ohms
- <1.2mm insulated wire
- Button cell battery contacts Anything powered by button cells
- 3 x button cell max size AG-13
- Small nut & bolt
also a Zippo style lighter, or other pocketable housing
(small altoids tin etc)
Tools:
- Soldering iron with fine tip
- Drill with 1mm, 2mm, 4mm and 12mm bits
- Small files / sandpaper
- Needle nose pliers
- Side cutters
- Tin snips
- 2 part epoxy glue / hot glue gun
- Pva glue / nail varnish
- Screwdriver
- Hacksaw
These images show what I was able to get out of a broken electronic die.
small electronic things like this are the best place to look for battery contacts.

















































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It is of course possible to make a detect circuit without having to program a chip. You can use a standard 555 timer to generate the pulse signal and have the ir detector directly trigger a buzzer. In either case you need to generate a pwm signal. Anything less than that would give too much interference, and mean more hard work tuning the sensor.
I think that the way I've made it is simplest (once you get the program on the chip). And if you're interested in this sort of thing I really encourage you to take a look at learning to use Picaxe. It's kind of the lazy choice, because I end up using it for everything instead of building proper circuits, but it's so easy to use.
http://www.picaxe.com/Getting-Started/Downloading-your-First-Program/
Thanks
I don't know what the convention is, and this was ages ago, so I don't really remember what I was doing but:
You should always check the pin out of your specific component with a datasheet, not just read it off of the circuit diagram. (I sent Tin Tin a longer message which should holpfully help clear this up)
My teacher said that IR Sensor Blowed up
Can U help Me here?
Please?
Good work. :)
However I don't smoke so I'm always trying to find more useful things to put in the neat little enclosure.
:)