On 28/04/2011 10:17, Huge wrote:
On 2011-04-27, Jules wrote:
On Wed, 27 Apr 2011 12:58:34 -0700, Mathew Newton wrote:
I've been experimenting with a break beam detector (a Velleman MK120
hobby-type kit consisting of an IR transmitter/receiver) and whilst the
detector functionally works and is great for detecting even a finger
quickly passing through the 'beam' I am not having quite so much success
with the smaller, and I guess faster, burst of nuts going through. I
have yet to try focussing the falling nuts via some waste pipe or
similar but I'm beginning to think even that might not help much.
Hmm, it should be possible - I've used grain counters before and they're
very reliable despite the smaller size of the grains. They held the
grains on a vibrating chute which had a *very* slight slope to it - the
frequency could be tweaked, but too high and grains would pour through
too quick and give false results much like you're getting.

Alternately, are the nuts of uniform enough size that you could use a
slotted wheel to pick one - but never two - up from a hopper and deliver
it past the beam at a "slow enough" speed?
When I worked for United Biscuits (who own(ed?) KP) I have some brief
exposure to the problems involved in packing mixed nuts and raisins(*). We
only counted brazil nuts, since they were large and expensive - IIRC peanuts
were packed by volume, since they are of reasonably constant size.

(* My real job was weighing flying crisps. Or persuading PDP11s and crisp
bagging machines to do it. This was some time ago, so my knowledge of
the technology is a tiny bit out of date.)


How about having a weighing machine of some type under the bowls and
trigger the stop when the correct weight has been reached.

either mod a electronic scale or make your own pressure sensor.