[sdiy] Proximity detector

[Peter Grenader]

Look at Robot e-stores.  These are quite common. There's chip and a small
assembly available with a UV led.sensor pair which returns a voltage
proportional to the distance to the object the UV light is bouncing off of.
I think it's has a range of up to 24 feet, something like that.

hope this helps,

Peter

Toby Paddock wrote:

> 
>> --- Fredrik Carlqvist <ifrc at iar.se> wrote:
>>> Hi!
>>> Does anybody know a circuit for detecting the presence of a
>>> human body? Kind of like the ones that open the doors at the
>>> supermarket. Preferrably, they would output a voltage
>>> proportional to the distance of the body.
>>> Fredrik Carlqvist
>> 
> Tim Escobedo wrote:
>> Someone recently posted some info about the QT301 chip.
>> ...
> 
> http://www.seanet.com/~tpaddock/c2cv.html
> I don't know if it will get the distance
> you need. I just tried it with the QT301
> and a 3 foot wire stretched out
> horizontally. It would start to see me at
> about 16 inches and was kind of jittery.
> 
> BUT,
> I tried the QT300, which is 16 bit serial
> output, instead of 8 bit PWM 'analog'.
> It would start to see me at about 24 inches
> and seemed to have a nicer response. I
> don't know mutch at all about the QT300 and
> I don't know how to talk serial.
> (The evaluation board does both chips and
> has an lcd display.) Yet another reason I
> need to learn about microcontrollers.
> 
> I didn't try tweaking the sensitivity
> capacitor (the eval board has 100nF) or
> antenna style. Might be able to squeeze
> out some more distance.
> 
> Later,
> Toby
> Paddock
>