Proximity sensor

Thread Starter

tnn

Joined Jul 21, 2017
40
Hi,

I made a proximity sensor with this IR emitter LL-503IRC2V-2AD and this phototransistor LTR-3208E
wavelength 940nm.

it works well, except if I expose it to sunlight both directly and indirectly ...

can you recommend something to solve?

can I put a filter in front of the window where the emitter and the phototransistor are located?

it is urgent thanks ...
 

Thread Starter

tnn

Joined Jul 21, 2017
40
ok, but you make me better understand how I measure the distance ...

as I did the circuit I have an operational amplifier as a comparator which activates above a certain voltage threshold ...

SENS.jpg
 
Last edited:

Thread Starter

tnn

Joined Jul 21, 2017
40
I'm sorry is this okay to power the 1khz emitter?

I have a 53% dutycicle okay anyway?

ne555 astabile 1khz.jpg

can you tell me the filter?
 

MisterBill2

Joined Jan 23, 2018
7,259
The photoreflective sensors that DO measure distance use an entirely different light sensing device, more like a line-camera. The mechanism of measurement is fairly complex and involves a lot more circuitry and logic. Also, those sensors cost a whole lot more.
 

MisterBill2

Joined Jan 23, 2018
7,259
Radio Shack, years ago, offered a long range beam break photo system that was really quite novel. The system used a stereo decoder IC as both the oscillator and the sensor circuit, and as long as the beam returned te "stereo" indicator output stayed active, but if the beam was broken then the output dropped. The beauty was that it used a phase-locked-loop circuit so it was almost impossible to trick the system.
 
Top