Re: Need help on very basic stuff

Ok. I am still not sure I am doing it right, but it seems to work. I
have a configuration where I use a 555 timer in astable mode, cranking
its frequency to what I hope is somewhere between 38 and 40 kHz. On the
other side, I have the Rat Shack IR receiver and a couple of
transistors and resistors and when I wave my hand between the two, my
LED on the receiver lights up.

I noticed, that it mainly picks up on a signal change, rather than the
emitter itsself, that's why I liked someone's suggestion (forgot who it
was) to use a second 555 timer to turn the emitter circuit on and off
in a range of about 1 to 10 khZ.

Getting that LED to light up tho, tells me its time to move on to the
next problem: How do I get that flash to translate to a signal to the
serial interface on my computer? (rs232). The wiring should be real
easy, but I can't find a simple circuit out there on the internet.

Does anyone have a good resource?
Thank you
Manuel


Chris wrote:
> mbaumann@xxxxxxxxx wrote:
> > Thank you, Chris and Rich. I noticed that even though I had some
> > classes on the topic back in College, I didn't retain the slightest bit
> > of practical knowledge about the topic. Therefore, you can imagine how
> > thrilled I was when my visible LED would actually turn on and off when
> > I put my finger through the beam.
> >
> > Since I actually AM in a hurry, (and I like experimenting better than
> > reading), please let me know what you all think about this circuit,
> > generously published by David Cook:
> > http://www.robotroom.com/Infrared555.html
> >
> > If I can make my Voltage lower to +5V DC steady, (with an LM7805),
> > can't I just build above circuit and voila? Or what major problems
> > would I face?
> >
> > And on the other end, I use the (276-640) 38kHz IR Receiver Module from
> > Radio Shack, possibly in combination with another LM7805 for voltage
> > regulation and maybe a transistor (as switch) for supplying the result
> > to the rs232 pin? Or can I use the power of the rs232 directly? I
> > remember having seen circuits on the topic, but I think there is some
> > danger involved.
> >
> > The electronics kit sounds like a good idea, but on the other hand, you
> > know how many parts I can burn out for 50 bucks? :-)
> >
> > Thank you all again for your help. I'll keep you posted about my
> > progress, if that's ok...
> > Manoo.
>
> The circuit in the link looks like it would do the job for the emitter.
> There aren't any docs on the RS detector (usually they just have
> connections to Vcc and GND, with the third pin as output which may
> require a pullup resistor). There should be a basic hookup diagram on
> the back of the package. Line up your LED and detector, then start
> pulling the detector away until the signal just disappears, tweak the
> pot until the signal comes back on, then stretch it some more. Repeat
> until you can't get a signal. That should be the appropriate tuned
> frequency for the detector.
>
> Good luck
> Chris

.

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