Well, my first thought would have been a two transistor blinker. (Common in
modle railroad setups for the signal lights.) It would be much more
tolerant of supply issues.

But since we're here now....

The most likly cause of your problem is short term power loss from
intermitant connections to the track rails. (a few mS) During that time the
draw of the motor is draining the capacitor,  try adding a blocking diode
between the car motor power and the blinker circuit. The idea is to prevent
the motor draw from discharging the capacitor for the blinker. You may have
to seperate the LED power too.


Happy holidays
-Denny




> Yes, the self flashing ones were the first suggestion but failed because:
> 1. We could only find red ones, no blue ones.
> 2. We could only find 5mm ones, not 3mm.
> 3. We wanted them to switch "left-right-left-right" not both blink at
once.
> 4. It would be cool to build something so small wich a CPU. :)
>
> /Magnus
> ----- Original Message -----
> From: "Larry Green" <larry.green@SYMPATICO.CA>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Thursday, December 25, 2003 3:32 PM
> Subject: Re: [EE:] Power problem in toy car
>
>
> > Subject: [EE:] Power problem in toy car
> >
> >
> > > Hi,
> > >
> > > for christmas this year a few friends and me decided to get out our
old
> > > track-car sets (correct name?) and build a big set.
> > >
> > > My friend has Sheriff's car www.student.bth.se/~pt98mvo/police2.jpg
> > > in which we wanted the nice flashy lights. So, I set up a AVR
AtTiny15
> (not
> > > a PIC, I know..) with a surface mounted 7805 on top (not much space
> > > available) and a pair of LEDs with a resistor each.
> > > www.student.bth.se/~pt98mvo/police1.jpg
> > >
> > > Problem: When the motor is running, the AVR is not getting enough
power,
> or
> > > possibly not stable enough power.
> > > I tried putting a 22uF condensator over the AtTiny, and that helped a
> bit
> > > but not enough. At idle speed it works, but at medium speed it starts
to
> > > reset and att full speed it does not work at all.
> > >
> > > There is also a condensator that came in the car, which might be
busted.
> > >
> > > What can i do? Do I just need a bigger condensator for the chip, or
is
> there
> > > another problem I need to address?
> > >
> >
> > Would it have been easier to just use 'self-flashing' LED's? I just
used
> two in
> > a project of mine as it saved battery power and I did not need to code
the
> flash
> > rate in the PIC. Just a thought.
> >
> > Larry
> >
> > p.s. Hope you had fun with the cars, I built a permanent routed track a
> few
> > years ago that never sees daylight anymore, must get it out one of
these
> days
> > and see if it still works.
> >
> > --
> > http://www.piclist.com hint: The PICList is archived three different
> > ways.  See http://www.piclist.com/#archives for details.
> >
>
> --
> http://www.piclist.com hint: The PICList is archived three different
> ways.  See http://www.piclist.com/#archives for details.

--
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