My suggestions for possible problem sources.

1. Insufficient power supply filtering.  Most of those race sets
transformers are nothing more than a transformer and a diode.  Works fine
for the motor, but not so good for electronics.  An easy test would be to
put a large (4000 uF or larger capacitor) in parallel with the transformer
output.

2. Noise generated by the motor.  Here your on board filtering comes into play.
        22uF and 0.01uF at inputs to regulator
        0.01uF at output of regulator

I like the suggestion about the diode for moments of power loss due to non
contact with the track.

Of the three, my first shot would be the power supply filtering.  It would
be my first shot and has the benefit of being the easiest to work on.

One way you can test to see if it may be a power supply filtering issue is
to put an oscilloscope on the tracks and monitor the voltage.  If you don't
have an oscilloscope, use a voltmeter instead and have it set to AC
Volts.  Monitor the AC component of the track voltage as you go from idle
to full on.

Scott



At 06:22 AM 12/25/03, you wrote:
>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?
>
>Thanks
>
>Magnus, Sweden
>
>--
>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.