Versatile and Low Cost Digital Counter

Hey, this is a really cool, yet so simple idea. Great Job! I do have problem with the soldering. I do have PCB however the solder does not stick to the board. Any tips?

Oops. Correction. It worked for a few minutes correctly, then the stiff wire started causing the "=" to go off on it's own multiple times. So then I tried another wire that wasn't so stiff, and it worked for a few minutes, then stopped getting connection. So, unless someone knows of a glue that is also a conductor, then that kind of calculator doesn't work for this application.

I bought that exact clear calculator, and it was easier than another than had an actual PCB. I wasn't able to solder the PCB at all, and that was if I was right about the place to solder it anyway. It was very confusing. But the clear calculator was much simpler, and I noticed that there were holes at critical junctures. I placed stiff wire in the 2 holes that lined up with the "=", bent it double, and crimped it down. It was no problem.

Who could start making these to sell with my skein winders. I need a silent counter to count number of revolutions. What would you charge to make 3 to test with?

ur telling me you cant make one yourself?

I just do not have the time. Need someone to make me six at a time or more.
Nels Wiberg

Yes, the calculator that I took apart was a printed circuity board and I do not know how to connect the sensor to that. I'm also too busy making spinning wheels to make fibers into yarn. If you would be interested in making them for me let me know. It would help with my Skein Winder sales.

its a nice idea...i never think to do this!

wat r u foreign or something? lol jk but to be honest the grammar really sucks.

Lol im not a foreing but I speak french

I got an idea to resolve the problem with the different calculators doing different things when you press "=", this uses 2 switches though
You know how it calculates when you press "+" or any other signs? instead of wiring the "=" button to the switch, wire the "1" and the "+", have the magnet or something trigger the "1" and then the "+", shouldn't be a problem to do for a spinning object, might look ugly on doors though.

exellent logic.

SWEET!!!!

Excellent Job. Is there a specific type of reed switch that one would use for this?

(I live the idea of the fridge counter :P )

you could make a homemade one (look up here) or buy one from mouser.com, or whatever. As long as its a true reed switch it should work.

I'm using one for a home alarm system... I believe it is a normally closed swtich - but I'd think a normally open would work too - the count would just happen at a different time.

could u help me with your digi counter i want to know were to solder my wire on the equals wen i run my wire over it it will just keep counting

How could you modify this to measure speed on a bike?

not speed

distance could be possible
multiply the circumfrence of the wheel by the number on the calculator and that should tell you in the same units ( metric / imperial / anything u invent ) that you used for the circumfrenecr of the wheels

Speed works on a completely different set up you would need to get rid of the calculator all together as you are couning the certain number of pulses per min or so many secs

Are you the one in your profile picture and is it recent? Because if so you are a frickin genius.

You Could Just Do Distance Over Time

Yep -- you'd need a timer... You can adapt the concept to do so (I think someone has a speed sensor in the magnet challenge contest ;)).

But, it can do average speed if you keep track of time :P

I wonder if you could do that with just a reed switch, calculator, and stop watch...

of course then again you could just spend $10 on a cheapo bike calc at walmart ^_

I did that a long time ago while in the Navy. I used it to keep track of my time left in the Navy by using a battery powered quartz clock with only the hour hand left. With two wired attached to the gauge glass of the clock, it acted like a microswitch. To debounce it I used a capacitor sourced from out in town. I was waiting for the day they would have a security scare from my short timer's clock.

The calculator would subtract half a day with each revolution of the hour hand shaft. What gave me the idea was the ship's driveshaft odometer! Nobody in naval history ever heard of this "short timer's clock". The calculator had a D battery rigged to it for when it was dark in the room.

A small improvement on the maker's reinvention, try a small capacitor across the leads of the reed switch matched for the anticipated fastest speed. With my version, I used a 220 microfarad cap becuse the crude switch so slowly made and broke contact and got "scratchy" for 2 hours per revolution.

Tis a pretty clever idea

Ok, I know this was from Sept, 2006... but I thought I'd point it out anyway... 23 openings in 58 minutes isn't 2.52 openings per minute ... you did it upside down - 23/58, not 58/23... think about it - 2 openings per minute for an hour would be 120 openings. I know, it's an easy mistake to make when you're just humming along and stuff... but as I say, just thought I'd point it out, for clarity's sake...
Cheers :)

Tres cool!

this is mycounter on my bike i used a lot of tape and some epoxy pipe sealant to attach the reed switch onto the front fork

as son as i saw that i said "omg (not really) gotta have!" so, i built it. in stead of using a reed switch and a magnet i used two wires and alluminium tape.

out of curiousity, why would you put the counter on your fridge door? Is it for a survey or just generally to see how often the door is opened in a day?

Yep - to see how many times/day the door is opened... If it's being opened a lot, and it's not you doing the opening, you can talk with the people in your house to try and cut that down. After all, for most setups, when you open the door - lots of cold air falls out :p

Pretty cool way of doing it i guess.

How exactly did you utilize the aluminum tape?... sorry n00b here.

awesome :D There's so many (potentially useless but fun to know) bits of data you can collect with it -- all you need is the right method to hook up. So far, I think the most fun is the fridge counter :P

I think I have (or had) that very same calculator :P

I used to have two of those. The screen cover broke on one.