> > opto for the inter-ticket holes which the PIC used for counting
>
> I noticed the motor is used in one direction only but has no
> flyback diode around it.  This may have been part of what
> was causing your glitches.  The 100nF caps slow down and
> reduce the peak voltage of the flyback pulse, but I think the
> transistor is still taking a beating

I couldn't swear to the fact there was no flyback diode. The
dispenser was a ready-made module and I made the best
notes I could without dismantling it. Aside from that though,
the carnival game this was part of was a rifle range using
flash tubes in the guns. A trigger-operated circuit dumped
450VDC into the flash tubes, which caused quite an electronic
ruckus. So even if the motor had been clean, the micro still
needed protecting

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