Which sensor should I buy?

I want to buy a sensor that is programmed to detect plastic. For example, if I put an aluminum bottle, the sensor will reject it and (with another sensor) make a noise that tells me it is not plastic

Aluminium is conductive, plastic is not, so you could just touch it with 2 metal probes (one connected to ground and the other one to an input with the internal pull-up resistor enabled) to know whether the tested item is conductive or not.

Testing aluminium cans is a bit more difficult though, since they don't conduct electricity very well, due to the labeling and/or coating.

Most recycling plants use aluminium's paramagnetic properties to separate it from the other waste.

Pieter

Thank you!! And which Anduino plate would you buy in my place?

valeriagallegos:
And which Anduino plate would you buy in my place?

That depends. You need at least 2 I/O pins: one for the sensor, and one for the buzzer. Every Arduino has more than 2 I/O pins, so the choice is up to you.
What else should your project do? Do you want to drive lots of LEDs for example?

For most beginners, an Arduino Uno is the best fit: it's simple and relatively cheap, so it's one of the most popular microcontroller boards out there.

Pieter

perfect!! thank you so much pieter

Hi,
Welcome to the forum.

You will also need a button to tell the controller when you are doing the test, otherwise it will say plastic all the time, even when no sample is being sampled, until you encounter metal.

Can you tell us your electronics, programming, arduino, hardware experience?

Thanks... Tom.. :slight_smile:

I would use a metal detector.
and an ultrasonic or a beam break.

the beam break /ultrasonic would detect that there was something placed.
then the metal detector would test to see if it were metal.

Thank you all, I am a first timer, so any help you can give me is greatly appreciated!!