Subject:
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Re: Re[4]: IR Collision avoidance
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Fri, 7 Mar 1997 20:30:20 GMT
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Original-From:
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Adam <adam@ring.zenox^IHateSpam^.com>
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Viewed:
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2212 times
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Richard,
Please send me the schemtics on the $2 circuit and whatever else
I need to know to get this thing up and running. I would appreciate
this very much. Thanks.
On Tue, 4 Mar 1997, Richard Whitehead wrote:
> Adam,
>
> I don't use -5v, I just use a single 5v supply. You have to choose
> your op-amp carefully - I am currently trying ICL7612 but I'm looking
> at another sort which might turn out to be better. With a single
> supply, you have to bias things around 2.5v using a voltage divider
> network.
>
> I am detecting the received IR using a demodulator (precision diode)
> circuit, which costs just about $2 to build. It gives an analogue
> output indicating the strength of the received signal. Hence there is
> no software involvement, except to poll the analogue port value.
> I am considering locking the receiver to the detector to make a
> synchronous demodulator, which might work better.
>
> One advantage of my approach is that you can test it using *visible*
> light if you want; because of the modulation, an ordinary red LED and
> visible-light phototransistor work fine, but with much less range than
> the IR reflectance sensor parts.
>
> I will post something specific on here once it is all completely
> finalised.
>
> Richard
>
>
> ______________________________ Reply Separator
> _________________________________
> Subject: Re: Re[2]: IR Collision avoidance
> Author: Adam <adam@ring.zenox.com> at Internet-Mail
> Date: 03/03/97 14:09
>
>
> Richard,
>
> I've tried the op-amp method and had some success. I just don't
> know how I would power the -5V via the HB. Do you have any
> suggestions? Thanks.
>
>
> On Mon, 3 Mar 1997, Richard Whitehead wrote:
>
> >
> > Bill,
> >
> > Why is everyone using a digital device to try to detect the (analogue)
> > distance to an object? Especially one with AGC, it makes no sense!
> >
> > I modulated the IR at 10KHz (high enough to be away from mains light
> > flicker, but out of the way of the remote control band), and am using
> > an analogue op-amp demodulator circuit to detect the strength of the
> > reflected signal.
> >
> > It is basically working, but I am just changing to a different op-amp
> > to get rail-to-rail operation.
> >
> > Richard
> >
> >
>
>
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Message is in Reply To:
 | | Re[4]: IR Collision avoidance
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| Adam, I don't use -5v, I just use a single 5v supply. You have to choose your op-amp carefully - I am currently trying ICL7612 but I'm looking at another sort which might turn out to be better. With a single supply, you have to bias things around (...) (28 years ago, 4-Mar-97, to lugnet.robotics.handyboard)
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