BUILD A SORTING
By Ron Newton
If you ever visited a
medical laboratory 25
years ago, you would
have probably found a
med tech looking
through a microscope,
using a hand tally
white cells, red cells, or
platelets. Or, they might
have been using a
sorting counter for
cells. Nowadays in
America, most of this
work is done using automated equipment.
In developing third world countries, they
still use the old method. Hand tally
counters cost $40 and sorting counters
run about $600.
Icombined both devices with a parts cost of $15 plus the printed circuit board (PCB). This is a great project for a
beginner or student because it will get you started in
doing soldering and interested in doing programming.
There is one surface-mount item (battery holder), then
everything else is through hole. The nice thing is that it
will fit in your shirt pocket.
Sorting counters have many uses: keeping score;
counting parts; counting people, e.g., classifying their sex,
age, etc. It is just a handy gadget to have on hand. Hand
tally counters are often used for counting people at events
or even cars on the road. Instead of using a sheet of paper
and marking four lines and a slash showing a count of five,
you just push the button (or buttons). The sorting counter
allows you to keep a total, plus keep track of specifics. For
example, if you are counting VWs on the road and want
to know the percentage of red, blue, yellow, green, and
black ones, you would use the differential counter.
44 July 2011
As I mentioned, this is a very simple project for those
who want to learn to solder or are interested in using
microprocessors and how they function. No special tools
are needed except for a small tip soldering iron. It has no
box as it stands alone, therefore there is no drilling. If you
want to change the programming, you will need a
Microchip PIC II programmer ($34.95;
www.microchip.com). Better yet, go to the Nuts & Volts
store and purchase their PICkit 2 starter kit for $49.95. It
comes with a board that will teach you additional
programming techniques ( www.nutsvolts.com).
The main point of this article is to teach the novice
about displays and multiplexing.
What It Does
This project has five counting buttons for sorting and
tallying. One mode button (blue) is for changing from
differential to hand tallies and one button (red) is for
clearing the results. When using the sorting function, it will
count 100 items displaying the numbers, sound an alarm
at 100, and then it will display the percentage of each
button when you push the sorting buttons.
When using the hand tally, it has three buttons which
will tally the counts. The first button advances the count
by one. The second button will count in batches of three.