Re: ][e paddle port annunciators...

[russotto@wanda.pond.com (Matthew Russotto)]

In article <969alp$p3i$1@acme.gcfn.org>,
Dave Althoff Jr <dalloff@gcfn.org> wrote:
>
>For Christmas, my brother gave me a neat toy...a KNex Ferris wheel kit. 
>Nice.  But the drive system on it is absolutely horrible.  It comes with a
>little 3v geared motor with a battery box containing two AAA-size
>batteries and a switch.  Trouble is, the motor has a worm gear, so it
>can't slip, and the wheel has no clutch on it.  Lousy engineering.
>
>But then, I have these ][e's lying about.  It seems to me that with a
>simple bit of machine code, I could turn the paddle port into a neat
>little DC motor controller, using the annunciator instead of the battery
>box to power the wheel.
>
>So the question is...How much current can I draw off of the annunciator?? 
>Not being much of an electronics geek, but knowing that the motor won't
>complain at being fed 5v instead of 3v...any advice for protecting the
>computer?  

I don't think you can hurt the Apple; IIRC if you try to draw too much
current it simply won't work.  You could place a resistor in series to
limit the current, if you're worried.  However, I doubt there's enough
current to run the motor-- they're 74LS-series flip-flops, IIRC.  If
not, you could use the annunciator to drive a transistor which ran the
motor off of battery power (or off a beefier 5v line)
-- 
Matthew T. Russotto                                russotto@pond.com
"Extremism in defense of liberty is no vice, and moderation in pursuit
of justice is no virtue."