Re: IR detector system, biasing of photo diode

On Sun, 27 Oct 2024 09:03:20 GMT, Jan Panteltje <alien@comet.invalid>
wrote:

On a sunny day (Sun, 27 Oct 2024 02:19:14 +0200) it happened Klaus Vestergaard
Kragelund <klauskvik@hotmail.com> wrote in <vfk0u0$3u9en$1@dont-email.me>:
>

Hi
>
I am working on an IR detector that will guide a robot into a docking
station.
>
A IR transmitter on the docking station transmits a beam, and 2 IR
detectors on the robot detects the beam and lets the robot navigate
towards the target. The working distance is a couple of meters.
>
I need it to be insensitive to ambient light/sunlight.

>
>
I use a cheap camera module to track a light source in H and V direction, and just a simple Microchip PIC : for processing
It can, with some added code, track object forms too, like a cross or maybe a big character.
panteltje.nl/pub/horizontal_IR_target_tracking_4686.avi
those camara modulea are IR sensitive to some extend, sometimes you can remove the IR filter from such modules.
It may be a bit of overkill for your application, but OTOH it can do a lot more.
Mainly designed to detect and follow jet exhaust..
You could uee utrasonics too, maybe even simpler, no sun problem, like a bat.
Cheap electret mikes? or modify some ebay 1 dolalr distance sensors...
can be used for anti-collision too.
>
 

Right. A sonic scheme could measure the phase between two mikes to
determine the direction of the source with high resolution. That could
be an analog multiplier or a bit of code. The amplitudes would be
useful too.

One could compute direction, distance, and velocity almost for free.

No problem with sunlight!

Cheap electret mikes have gain inside, a jfet or an IC, so there would
be lots of signal to go straight into a uP ADC pin.