Subject:
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Re: electronics question please help
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Mon, 22 Feb 1999 23:54:43 GMT
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Original-From:
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Eric Noyau <noyau@apple(StopSpammers).com>
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Viewed:
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857 times
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At 13:18 2/22/99 , Bob Kelly wrote:
> Hello all,
>
> I hope there is a simple answer for this...
>
> I have attempted to build the circuit that will allow IR object detection
> using the Sharp IR detector module and a pair of "high output" infrared
> LEDs. The circuit I built was the one from "Mobile Robots - Inspiration to
> Completion, 2nd ed."
>
> The circuit calls for, among other things, a 74HC04 inverter. I obtained all
> the components from my local Radio Shack. The Inverter that I got is
> actually a 74HCT04 and the IR receiver was the same part number specified
> with the exception of a "B" suffix (hopefully to denote vertical mount Vs.
> horizontal mount). I implemented a slightly modified version of code to read
> the sensor that was based heavily on the info given in the book (I timed the
> LED pulse as required).
Been there, done that! Funny. I bought almost all the same stuff from my local shack. Writting the software was the easy part ;^).
>
> Obviously, or I wouldn't be asking questions, the thing doesn't work. The
> LEDs are working (saw 'em through the video camera) and there is power to
> the Detector (yes, I grounded the case). I wired everything painstakingly
> per the diagram but I was wondering if it is necessary to supply steady
> voltage to the inverter (I have not, and the book didn't tell me to.) I did
> ground the inverter however.
I've supplied some power to the inverter, yes. I'm assuming it's mandatory to have the inverter actually work. Otherwise how do you expect to invert a zero signal? It need some power from somewhere...
If I remember correctly it took me a while fiddling with the variable resistance before having the receiver getting a signal. I then put some hot glue on it to seal it and I haven't changed it since.
My version is working but is *way* too sensible: it detect an obstacle from at least a couple of meters away ;^). I tried changing the two resistances controlling the LED output to something bigger to limit the current going to the LEDs with no noticable changes in detection range. Any suggestion to get this thing less sensible would be appreciated.
> [...]
> I am new at electronics and I thought this might be a nice "get my feet wet"
> starter project. I don't have access to fancy testing equipment so any help
> at all would be greatly appreciated. I apologize if this question is a
> little on the basic side.
Hey man, it's not that basic for me. I'm a software guy, so take all my hardware advices with a grain of salt ;^)
-- Eric
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Message has 1 Reply:
 | | Re: electronics question please help
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| Eric - - You might try shielding the IR sensor ... add successive layers of "Scotch" tape until you get the desired sensitivity. I'm using layers of black plastic trash bags ... it blocks a lot of visible light, but very little IR. - - - Nick - - - (...) (26 years ago, 23-Feb-99, to lugnet.robotics.handyboard)
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Message is in Reply To:
| | electronics question please help
|
| Hello all, I hope there is a simple answer for this... I have attempted to build the circuit that will allow IR object detection using the Sharp IR detector module and a pair of "high output" infrared LEDs. The circuit I built was the one from (...) (26 years ago, 22-Feb-99, to lugnet.robotics.handyboard)
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