Simple I/O Reading with Parallax Prop and Infrared

Discussion in 'General Electronics Chat' started by ryfitzger227, Jun 2, 2013.

  1. ryfitzger227

    Thread Starter New Member

    Dec 4, 2011
    This might seem like a simple question to answer for some, but I'm completely stuck with this. I just can't get it to work how I want it for anything!

    I'm using a Banner Engineering MULTI-BEAM Sensor with a PBT Power Block. Information here: . It's job is to send a signal to a Parallax Propeller I/O pin when the beam is broke and reflecting. In other words I'm trying to get it to equal 0 & 1 and then register that on the prop. The way the MULTI-BEAM PBT Block works is that Pin 1 is VIN (+12v), Pin 2 is VSS (-12v), and Pin 3 is connected to VSS through a transistor. When the beam is reflecting, that transistor gets energized and makes pin 3 -12v. I got this to work a while back by connecting Pin 1 & 3 to the coil of a relay and then put one side of the relay to ground (through a 10K ohm resistor) and the other to VIN. This worked just fine and registered in the prop as 0 & 1. I don't really want to use a relay, rather a transistor (if that's what I'd have to do). The only problem is I don't want it to have to be something that I have to replace often. It needs to be able to run for long periods of time (12 hours a day) and not have to replaced, well - forever. I've had problems with transistors before with them getting too hot and others just stop working. I'm sure that's just the way I've been wiring them up. And relays are just becoming old technology and they still have to be replaced every so often. Another problem is that the infrared is powered by 12v and the maximum Input voltage on the prop is 3.6v. In other words, I'm looking for a reliable way to hook up this infrared to a Prop so it can tell when it's reflecting and when it's broke.

    Any answers, suggestions, and comments are greatly appreciated.
    Last edited: Jun 2, 2013
  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    Put a pull up resistor (10K to 100K or so) from PBT pin 3 to the Propeller Vcc, then pin 3 to the input.

    That gives you a logic level your chip can detect.