Proximity Switch for LED via IR

Discussion in 'The Projects Forum' started by gravymister, Aug 21, 2012.

  1. gravymister

    Thread Starter New Member

    Aug 21, 2012
    1
    0
    Hi, I'm trying to build a very simple (and cost effective) circuit that when you place a cup of beer down it lights up the LED and when you take it off the LED goes off. For a Beer Pong table I've built.

    I've found a few schematics online that use phototransistors but since I need 20 of these circuits its simply too expensive to buy 20 phototransistors (plus all the other stuff for those schematics).

    I have stumbled across one simple circuit that uses an IR LED as a receiver with an op amp (http://www.artemlive.com/cgi-bin/news?c=v&id=758) but the website doesn't give the full schematic and the image of the breadboard is pretty confusing.

    I only have a vague knowledge of op amps myself, but would I be correct in saying the circuit schematic below would work and in the probable case that I've made a glaring error what could I do to rectify it?
     
  2. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    395
    Is '" the LED " going to be under the beer container, or in a ring around the container? What containers are allowed?
     
  3. #12

    Expert

    Nov 30, 2010
    16,269
    6,781
    Along the same idea, does beer reflect IR?
    Does the cup reflect IR?
    There is just so much information I don't have. I've rarely said this but, could you ramble on a while? Do you have ideas about flush mounting the sender and receiver? Cutting a shallow divot in the surface so the beer cups will be properly located?

    ps, that battery symbol in your drawing seems wrong. Is it trying to be a ground symbol?
     
Loading...