I am in search of a circuit which works with IR or RF wave with a range of 100 meter to detect proximity or burglar.

I need this to detect the presence of human or animals One thing important is i can only use the circuit in this way.

0metere ------------------------------------------------------- 100 Meter

Signaler (IR) ...................................................................>|(obstacle)

Receiver (IR or RF) <---------------<---------------------<<<<|(reflected from obstracle)

That is I cant place the receiver at the end of 100th meter, but it much work with reflection...

I have found the same circuit but it has a small range of less than a 0.5 meter

The circuit I have found is "Circuit download...."

  • \$\begingroup\$ 100m is a very long way for an IR reflective detector type of circuit, they are normally used at much closer ranges. Have a look at PIR sensors and Fresnel lenses (or a different narrow range lens if the detection area is small), some of the external security light type circuits have a pretty long range. \$\endgroup\$ – Oli Glaser Mar 17 '13 at 6:33
  • \$\begingroup\$ Would a 'pencil' beam like a laser be OK? It might be worth updating the question to say at the end of the 100 meters how broad the detection area should be, and if it needs to be exactly 100 meters range or if say 100-200 would be OK. \$\endgroup\$ – PeterJ Mar 17 '13 at 6:33
  • \$\begingroup\$ @PeterJ , is it possible to but pencil beam laser from market ? , i need anu thing which must be invisible and also the range is 0 to 100meter that is within the range \$\endgroup\$ – cc4re Mar 17 '13 at 6:38
  • \$\begingroup\$ @OliGlaser : can you explain me a little bit clear , is it possible with IR or RF or need to go with anything , this is for outdoor purpose the medium must be invisible \$\endgroup\$ – cc4re Mar 17 '13 at 6:40
  • \$\begingroup\$ @cc4re - Yes, this is totally invsible as it does not output anything - PIR stands for Passive Infra Red sensor, it works by detecting the IR emitted from hot objects (e.g. body heat) compared to the surroundings. Have a read of the Wiki page and see if you think it's suitable for your project. \$\endgroup\$ – Oli Glaser Mar 17 '13 at 6:42

There are quite a few PIR circuits, ranging from very simple to quite complex. The better ones use a window comparator setup and adjust for ambient light conditions.

Here is a page full of PIR circuits, and another good page from LadyAda. An app note detailing some common circuits.

Here is one pretty typical circuit (from this page):

Example 1

Here is about the simplest circuit:

Example 2

And one that appears to have ambient light compensation (notice phototransistor at bottom left)

Example 3

Have a read through the tutorials/links and then have a browse around for circuits, there are literally hundreds of examples out there, some better (and better explained) than others. Choose your lens carefully - if you don't want a typical wide angle security type detector, then I think this will be crucial to getting good results. Experiment with a few options to see what works best.
The PIR sensors (component only) are available from places like Farnell, Mouser, LadyAda, etc. Or you can purchase ready made modules from various places.


We have had pretty good results using the Zilog ZMOTION chip to build a PIR sensor for shorter distances around 20-30 feet with an appropriate Fresnel lense. To get any where close to your 100m detection range would definitely require a custom designed Fresnel lense. BTW We also worked with both Ultrasonic and simple X-Band microwave designs neither of which were capable of reaching 100m range.

There is some good information on the Zilog site: http://www.zilog.com/index.php?option=com_product&task=product&businessLine=147&id=148&parent_id=148&Itemid=77


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