Guys,

         Just wanted to give some feedback on all the suggestions that have
been submitted.  BTW, there have been a lot of suggestions.  I appreciate
it a lot.
         I went through the suggestions and tried them.  Listed below is
what I tried and how well it worked.

1.      0.1uf cap across relay coil - no help
2.      4.7ohm resistor in series with relay coil - no help
3.      Checking all inputs for noise or floating inputs - no help
4.      10nf cap from C to E on the transistor - no help
5.      Put 0.1uf cap across relay contacts - partial success.  Instead of
failing like 75% of the time, it only failed about 10% of the time
6.      Put two 0.1 uf caps across relay contacts (in parallel) - better
partial success.  Failed probably 5% of the time.
7.      Moved the caps to the terminals right on the motor - better
success.  Failed probably 1% of the time.

         I'm saying failure is when the PIC resets or jumps to a random
place in the code.
         So, I'm thinking if I put a bigger cap on the motor winding
terminals, it will help even more.  Question is, how big of a cap should I
use?  I can't use an electrolytic b/c the motor reverses direction.  Anyone
have a suggestion?  Hopefully something fairly cheap.

Thanks,

Gary


At 02:55 PM 8/28/01 -0400, Dan Michaels wrote:
>Gary Neal wrote:
> >Hello,
> >
> >        I've got a 16f870 that I'm using to turn a relay (Tyco V23105 150 mW
> >Nominal Coil Power, 960 ohm, 12 volt Nominal Coil Voltage) on/off.  This
> >relay is controlling a very small DC motor (~0.5amps).  About 10% of the
> >time when this relay turns on/off, it resets the PIC.  I've verified this
> >is what's happening.  Seems to work fine when the motor isn't connected to
> >the relay.  Only resets when the motor is connected.
>.......
>
>
>Sounds like you need a suppressor across the relay "contacts", or
>better yet at the motor itself. Since a DC motor, try a reverse
>diode there or a snubber - 10-100 ohm resistor in series with a
>0.1 uF cap across the motor winding. The cap should be better
>quality than simple low-V ceramic. 200V or so polypropylene.
>
>- dan michaels
>www.oricomtech.com
>========================
>
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