Phototransistor Raspberry Pi

Hello guys, is phototransistor an ideal sensor for detecting objects? distance to detect the object from the sensor most probably around 1cm.

Or LDR is ideal for this?

any ideas or suggestion is greatly appreciated.

Thank you.

that highly depends on the object itself (if it was glass or ???), on the speed of it and size of it and ....
What should be detected at all (there should be at least 2 different states)

Hi Pan64, basically it is some sort of a close range detection.

The object is a medicine pill.

Thanks.

I do not think you can measure any range/distance or similar with that, but you can check if the pill is there (or not). But probably I misunderstood something

Not enough information to say. As stated you can use them to detect a change in state. One example is an encoder that switches between black and white lines.

Hi,

A Photo transistor would not be the best choice since distance of the moving object would not effect the transistor unless the change is reflective to that device. Maybe looking into IR or look here; https://en.wikipedia.org/wiki/Passive_infrared_sensor to possibly modify detection of a small object at a distance. Even then the reaction thresh hold time may not be fast for a moving object that small.

Hope this helps.
Have fun & enjoy!

Hi guys, thanks for all the replies.

Pan64 got it, I just want to check whether the pill is present or not.

What's the best option for this?

Originally Posted by michaelk Not enough information to say. As stated you can use them to detect a change in state. One example is an encoder that switches between black and white lines.

Hi Michaelk, can elaborate further what do you mean by switching black and white? What's an encoder?

You may want to detect if that thing moves, spins, you may want to identify that object (shape of it), you may want to measure its size, or there is a pattern on it you want to identify, want to know its weight, color ...
So there can be a lot of things .... In some cases you may need an encoder to do the job, but I do not think we need to go into details right now.
If you want to know only if there is something in between the LED and that transistor your setup may work properly (although you will not be able to tell if that was your finger, a screwdriver or a pill).

The pill is in stationary mode, it's not moving. I only want to know whether in the holder, there is a pill and I am thinking whether a Phototransistor is able to do the job.

depending on the layout, a phototransistor can be a good solution.

Hi,

Originally Posted by JJJCR The pill is in stationary mode, it's not moving. I only want to know whether in the holder, there is a pill and I am thinking whether a Phototransistor is able to do the job.

If the pill is contained and not in motion then an interruption on when the pill enters and remains in position could be done by interruption of the beam from a source to the photo-transistor. As long as the state remains then that could be sense for the pill or whatever is breaking your beam for the Photo-transistor. Your pill and beam should be contained so there are no leaks for the threshold settings of the detection. Your source beam must be finite and not cause to much flooding. The container material will need to have the beam and sense transistor aligned to provide a path to be broken by the pill. Ambient light could be factored in for the sense levels to allow bias of the Photo-transistor. Or use opaque material for the container then align the source and photo-transistor so a proper trigger point will occur.

Hope this helps.
Have fun & enjoy!

Thank you guys, a lot of mechanism is on my mind.

But I haven't really find a good time to implement in order to find out the limitation or whatever is the best way of doing it.