Let's Make Robots!


A particular sensor

Hello. So I reread the rules and am going to pose my dillema as specifically as I can. I've been researching it for a couple weeks and am still stumped, so please bear with me...I'm just a beginner.


Here is the problem I am trying to solve, posed metaphorically.

What sensor exists, that would allow you to detect a particular tennis ball being dropped into a bucket, only that tennis ball, and no others? What would I have to attach to the bucket AND that one tennis ball that could detect and alert me it just passed into the bucket?

LDR vs Ir Phototransistor

Hi  Everyone

I'm doing research for my first bot from scratch. I was hoping someone could point me to a good source of info on the advatages/disavantages of using LED & LDR vs Ir with Phototransistor for proximity sensors.

My basic goal for them is to have an edge detector in each corner and a line following array. I thought the LDRs would a simple and cheap approach but was surprised to see how cheap this Ir LED & Phototrasistor set was.

Infrared Proximity Sensor

I have a Infrared Proximity Sensor. Is there a way to debug the distance so I know how far I want it to detect something. I always see people's codes have 400 and 700 and I'm like where did they get those?