Looking to build a counting device

I'm lame at electronics, but i want to build a device that would have either LCD or LED display with 3 (or more) digits. the counter would have a sensor that would increment the count by one each time a magnet passes in front of the sensor. It needs add and subtract capabilities (increment one or decrement one by pushing a up button or a down button.) It should run on AAA, AA or 9V battery. Where should I start to find a schematc, instructions or plans to build or buy such a thing? I used to have an exercise machine that did this, but can't seem to find such a thing on google. Probably not using the right buzz word. (':wink:') (help?)

TIA

I'd use a 74ls193

http://vivisimo.com/search?query=74ls193&v:sources=Web&x=45&y=15
click on projects in the left hand panel
should give you a place to start.

Keep us posted on how the project turns out!

Cool, thanks. One piece of the puzzle. I picked up a Radio Shack Engineer's Miini-Notebook Magnet and Magnet Sensor Projects book... It talks about Hall Sensors. Yikes. I "think" a Magnet Position Detector may be suitable? I am a total newbie. the Projects link didn't contain anything other than info on the chip you recommended that I found to be useful so far.

Once the puzzle is complete I will be sure and make lots of noise.

if you cannot find any thing I'll scan in a copy of one of my books that contains a project.

Here it is

https://www.angelfire.com/alt/martinskitchen/counter.html