Counter/ Timer Circuit

[DaveK]

I’m a baseball coach at a high school and when we use our pitching
machine our players want to hit more balls than they should. I would
like for an alarm to go off after a pre-determined amount of pitches.
The machine has an arm connected to a wheel that rotates. Each full
revolution equals one ball pitched. I would like to count each
revolution (pulse) of the wheel either by a limit switch or even a
reed switch with a magnet on the wheel. Maximum pitches would be
somewhere around 10. There is 110 vac at the machine so I can run most
any dc voltage through a transformer to run a circuit. I have played
around with the 4017 counter/divider and the 555 timer but I don’t
seem to be getting anywhere. What would be the correct type of circuit
to use for this type of application?
I’m not real experienced with electronics but I can follow a schematic
and build a circuit. I would have to have a complete schematic in
order for me to do this. I’m not sure how much time it would take to
make a schematic of this sort but any information would greatly be
appreciated.

Thank You for Your Time
Dave

 

On Tue, 24 Nov 2009 19:43:32 -0800 (PST), DaveK <piscatory@cox.net>
wrote:

I’m a baseball coach at a high school and when we use our pitching
machine our players want to hit more balls than they should. I would
like for an alarm to go off after a pre-determined amount of pitches.
The machine has an arm connected to a wheel that rotates. Each full
revolution equals one ball pitched. I would like to count each
revolution (pulse) of the wheel either by a limit switch or even a
reed switch with a magnet on the wheel. Maximum pitches would be
somewhere around 10. There is 110 vac at the machine so I can run most
any dc voltage through a transformer to run a circuit. I have played
around with the 4017 counter/divider and the 555 timer but I don’t
seem to be getting anywhere. What would be the correct type of circuit
to use for this type of application?
I’m not real experienced with electronics but I can follow a schematic
and build a circuit. I would have to have a complete schematic in
order for me to do this. I’m not sure how much time it would take to
make a schematic of this sort but any information would greatly be
appreciated.

Thank You for Your Time
Dave

I would be incined to point you to one of the easy microcontrollers -
the PICAXE. It's programmed in a dialect of BASIC, so you may already
have been exposed to it. If not, the chip is aimed at education (late
elementary and up) in the UK.

The big advantage would be the ease of changng the number of cycles
allowed (via a Sony IR remote control) and the ease of changing the
type of sensor: mechanical switch, optical switch, magnetic switch
(including the Hall effect chips).

The startup expense would be under $50.

I can almost guarantee that you will find "bells and whistles" to add
to the design once you have the basics working.

The home site is here: http://www.rev-ed.co.uk/picaxe/

There are several US suppliers:

http://www.advancedmicrocircuits.com/

http://www.phanderson.com/picaxe

http://www.sparkfun.com/

http://www.robotshop.com/

They have a VERY active support forum: http://www.picaxeforum.co.uk/

I'm in Georgia, near Atlanta. If you're close by, I can work with you
on getting a design that works. Working from pictures and approximate
measurements may not work as well...

John

 

[ehsjr]

DaveK wrote:

I’m a baseball coach at a high school and when we use our pitching
machine our players want to hit more balls than they should. I would
like for an alarm to go off after a pre-determined amount of pitches.
The machine has an arm connected to a wheel that rotates. Each full
revolution equals one ball pitched. I would like to count each
revolution (pulse) of the wheel either by a limit switch or even a
reed switch with a magnet on the wheel. Maximum pitches would be
somewhere around 10. There is 110 vac at the machine so I can run most
any dc voltage through a transformer to run a circuit. I have played
around with the 4017 counter/divider and the 555 timer but I don’t
seem to be getting anywhere. What would be the correct type of circuit
to use for this type of application?
I’m not real experienced with electronics but I can follow a schematic
and build a circuit. I would have to have a complete schematic in
order for me to do this. I’m not sure how much time it would take to
make a schematic of this sort but any information would greatly be
appreciated.

Thank You for Your Time
Dave

Allelectronics sells a LED chaser kit that has 10 LEDs,
a 555 and a 4017 plus a few other components for < $7.00.
You could easily modify that for your application. Either
eliminate the 555 entirely and use a switch + debounce
circuit to clock the 4017, or reconfigure the 555 to a
one shot and trigger it from the switch. (Essentially,
that uses the 555 as the debounce circuit.)

You'll most likely want to connect the 4017 output to
a transistor and use the transistor to drive the alarm.
Post details on the alarm you intend to use - if you have
access to ABSE a schematic can be posted there.

As already pointed out, a PICAXE (or a PIC or other
microcontroller) would give you greater flexibility,
but you have to contend with the learning phase and
initial cost for a programmer. If you have the time
and the interest, learning to use a PICAXE/PIC/whatever
is worthwhile.

Ed