I think I'm pretty good at putting things into motion e.g. actually getting them fitted into trash-bins after liaising with city councils, but it would take me an age to learn enough about circuits to design something that fits the purpose. I couldn't do it all quickly enough, hence the request for some aid.
But I have done some background reading and have some questions:
Sonar sensor vs. Light dependent resistor
in use 2 amps
How long between pulses would be an acceptable time period? A piece of trash can be placed in the bin in half a second, thus a pulse every quarter a second might be needed.
Would I need a capacitor to handle this jump in power requirement? If so, should I power this from a separate source rather than risk the microcontroller losing too much power?
Cost about $30
Light dependent resistor:-
Inexpensive, less-power needed for detection(?). The problem I can see here is that as light alters throughout the day, activation may occur when the sunlight changes, or a clous passes. Thus, would it be possible to calibrate it based upon rate-of-change of resistance (the change in power)?
I love the sonar-sensor and speakjet chip, although a little pricey if stolen.
I'd be happy with the falling sound if it was effective, and then maybe progress onto the sonar-sensor and speakjet chip if it proved popular and needed tweaking to keep it popular in the same location.