Post by thread:[OT] IR-sensor

> I have a IR-sensor with an open collector output. > Can somebody be kind and explain how it works > or show me with a drawing will be nice! MOST LIKELY, when exposed to IR light above a certain threshold, the OC pin will be pulled to ground. Or maybe if exposed to IR light pulsed at a certain frequency. Or maybe the amount of current flowing into the OC pin will vary depending on the amount of IR light incident to the sensor. It's hard to say, exactly, without more details of the product involved. Mike H.

From: "Åke Neehr" > Hello! > I have a IR-sensor with an open collector output. > Can somebody be kind and explain how it works > or show me with a drawing will be nice! Since everyone seems to be preocupied with the new age religious thread about free love and the like, I'll give it a shot. ;-) The open collector output means that you will need to supply a pull-up resistor on the output pin. This resistor will connect the output pin to Vcc (the positive supply voltage, ie +5V). A 5K or 10K should be fine. The detector will respond to a signal modulated on what is probably a 38kHz carrier. It could be 40kHz or even 50ish depending upon the specific IR receiver. As I recall, when the carrier is present, the IR detector will pull the output low and hold it. When the carrier is not present, the output will float high. IOW, the carrier itselft is stripped from the signal. Data is sent at a much lower rate than the carrier frequency by simply turning the carrier on and off at some predetermined rate. The raw data will appear directly at the detector output pin.

> I have a IR-sensor with an open collector output. > Can somebody be kind and explain how it works > or show me with a drawing will be nice! Do you realy expect a response without providing the type number? Did you check the datasheet? Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: http://www.voti.nl consultancy, development, PICmicro products docent Hogeschool van Utrecht: http://www.voti.nl/hvu

> Since everyone seems to be preocupied with the new age religious > thread about free love and the like, I'll give it a shot. ;-) It's actually *very* old age, and labelling opposition to what has proven over millenia to be "common sense" as 'religion', as many involved in such discussions do, is used as an excuse to attempt to deny reality. Reality usually fails to notice :-). But, apart from that, your explanation of the operation of an open collector IR sensor was a very good one, especially so given the brevity of the question. RM

If it is the open collector part that has you confused.... The open collector output allows more than one "open collector" output device to be "wired ored" to the same point. One pull-up resistor required regardless of the number of output devices hooked to the point. When no outputs are conducting, the point is high, when one or more devices outputs then the point goes low. Sort of a "poor man's TriState". Bill ----- Original Message ----- From: "Åke Neehr" <spam_OUTake.neehrTakeThisOuTtelia.com> To: <.....piclistKILLspam@spam@mit.edu> Sent: Thursday, October 06, 2005 2:39 PM Subject: [OT] IR-sensor Hello! I have a IR-sensor with an open collector output. Can somebody be kind and explain how it works or show me with a drawing will be nice! Regards Åke

At 11:39 PM 10/6/2005 +0200, you wrote: >Hello! > >I have a IR-sensor with an open collector output. >Can somebody be kind and explain how it works >or show me with a drawing will be nice! It would be better if you could post a link to a datasheet. "Usually" industrial sensors with open-collector outputs have an NPN transistor with emitter common with the (-) supply. So, you'd typically use a pullup resistor somewhere in the circuit, or use a PLC input which has it built-in. In some very benign situations (short wires, all inside one enclosure, little electrical noise) you might be able to go directly into a PIC port pin and omit the signal conditioning and isolation, but that's oh so seldom true in industrial situations. (view with fixed-width font) +12V or whatever rated supply voltage o VCC | + | | | pullup | | Sensor \ .-. .-------------------. | | optional isolation and | | | | Signal conditioning | | '-' .----------. | | | | | | +----------+--------| |-----o | | |<- "open | | logic | ___ |/ | collector" | | level | -|___|---| | | | | |> | | | | | | | | | | | | | '-------------------' '---.------' | | === === GND GND Your sensor should come with specs that spell out the range of supply voltage it expects & the current and voltage rating of the output. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" speffKILLspaminterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com ->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff

<oops, sorry about the reply to the very old post, have to watch the sorting!> Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" .....speffKILLspam.....interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com