need some ideas for a perimeter alarm

[joulian]

I want to build a device that i can more or less mount in a hat or something like a belt that will alert me to something approaching. Something that works off heat perhaps. I work outside sometimes on projects and it gets dark on me and I would like to know if someone is sneaking up on me.  I think the problem would be excluding myself from being detected. I was thinking i could use a cell phone vibrator to alert me if someone is approaching.

Any ideas on circuits that might assist in the making of this project?

 

[Herman the German]

Hi Joulian,

the problem would be an omnidirectional sensor. It must be rotating either mechanically or electronically like a radar antenna.

That sensor system being carried by a person has yet to be invented.

What is your personal problem?

Are you afraid being alone in the dark?

Do you have reason to believe that somebody intends to threaten your life?

If you honestly answer any of my questions with YES you don't have an electronic problem, but one a good psychologist can solve (together with you).

Regards

HtG