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Re: IR Detectors (Int & Comp)

On Tue, Jan 11, 2000 at 08:58:23PM -0500, Joyce Poon wrote:
> I saw the specs for the OP505 today.  Everybody agreed that savvysearch 
> didn't work very well -- this guy looked it up thru altavista.  The
> detection angle is indeed 18deg for the full angle.  Blind spots may be a

I don't understand why you're so worried that it will be hard to find
a better chip.  I still propose that people use the op505 because they
_want_ the narrow detection angle.  I may be wrong.

> I also found out that another grp wants to do PWM for IR input to the
> comp.  However, they couldn't find the nec circuitry.  I thought I had
> seen the circuit req in the manual, but I was wrong.  Do you think it is
> possible to do PWM for IR input? (also keep our comp clk count & speed of
> 6502 in mind)

Do you mean that they intend to turn the IR output from the sensors
into a pwm signal?  Sure, it's possible, but I don't see the advantage
to it, other than sucking-up-to Malone.  I would urge that group to
reconsider their plan.

But yes, of course, it can be done.  After filtering and rectifying
the sensor output, plug it into a voltage-controlled oscillator
circuit.  There are chips to do this (ask Steph Pereira), or it's very
easy to design your own circuit for this --- you may recall we tried
to design such a circuit but failed ...  :)  ... I think our failure
would be a temporary condition if we tried a little harder.  Then run
that to the comp who simply reads the input and analyses the pulse
rate comparing the number of oscillations to a timer.

Using all these cookie-cutter circuits and chips is getting boring.  I
think we should design some more of our own.  1/2 ;-)

> One more bit of info (possibly useless): we can safely assume that the
> room for the competition is windowless (Malone said so).

ie. less IR interference.

> Lastly, I have to learn how to solder.  I think you (Tim) have to do some
> soldering to assemble the 6502 board.  Is it possible for me to do some of
> the soldering for your board so that I can learn how to solder?  This

Uh, that's one possibility.  How say you come over to my room
sometime and play with my cheap-ass soldering iron instead.  Then
I don't have to worry about my 6502 board getting fucked-over.  :)
I have an old keyboard you can take apart.  It's a very old one so
there should be plenty of PCB for you to have fun with (unlike
these new-fangled ones they always sell).  For the purposes of this
exercise it would be useful to bring one of the
solder-sucking-vacuum-thingys from the lab.  Try to sneak into the
lab on Wednesday.

Signature withheld by request of author.