How to Make a Simple Counter of a Calculator

How to Make a Simple Counter of a CalculatorWe often need a counter, for instance, to calculate the number of turns or hits. However, we don't always have one at hand. But there is always a way out. You can make a counter out of a calculator. In fact, it is quite easy. Let's take a calculator and disassemble it. We remove the screws. Then we need to access the pads under the keys. In this case we'll have to remove the plastic holders. However, usually these pads are attached by screws.Having done that, we find the first and the second contact of the equal sign. We solder wires to these contacts. Then we connect a magnetically operated reed relay to the wires. The reed relay will substitute the equal sign key. As a result we get a programmable counter. It can count not only whole numbers adding by one or two but also some other values.Let's clear the pads and cover them with flux. Now we tin them. We cover the wires with flux and then also tin them. Then we solder the wires.Now we straighten up the wires and close the body. It is not necessary to tighten it with screws. We close it till the catch clicks and that is enough. With the help of alligator clips we attach the reed relay to the wires. Now we can check how the counter works.But first we need to program it. We dial 1+1 and bring the magnet close to the reed relay several times. Now we can see that numbers on the screen are changing as the counter counts how many times we brought the magnet to the reed relay. For example, this time it's 14.This also works when we unwind a coil. If there are 500 turns we can unwind one at a time. With each turn the number on the screen will decrease by 1.The calculator can also count fractions. Let's assume that by winding a coil we increase its inductance by 0.73 millihenry. So we dial 0.73+0.73 and continue counting. In this way we don't count the number of turns but the inductance of the coil at this particular moment. At some point we will see, for instance, that its inductance has reached 6.57 millihenry. This is close to what we need and we can stop here.At the same time the calculator can still be used with its original function. It can still count, multiply and divide. But the wires on the equal sign allow us to use it in this unusual way.

[@in3432]

Bro this idea is pure genius, so simple but yet exactly what I needed. And to be able to vary the amounts AND still use the calculator. Brilliant. Going to the pound store tomorrow for cheapo calculator. I tried it on my scientific calculator ( old one) I found the contacts a bit more complicated. So stick to the cheap calculator two contacts for the equal sign. Thanks

[@wipranksta]

And here I was about to buy a $40 7-digit digital counter. Thanks for the idea! Can't believe I didn't think about this!

[@rockyrodriguez2351]

Damn! This guy is ahead 5 years Applying this idea, I already had This 10 years ago, I'm jealous Anyhow it's good to know That any idea could work If you just put an effort to it. Don't get me wrong, by The way I like this video to me It's a five Star rating and I'm sure it will Help a lot of you tubers.

[@ridefast0]

Hi - great for counting turns, but you can't calculate inductance like that. Because the inductance increases with n^2, that means that the inductance added per turn is not a constant, it depends how many turns are there already. So you can use a spreadsheet or a calculator or an app to work out how many turns you need to add or take off, then count the turns using this great method.

[@schitlipz]

Good idea for new use of inexpensive dollar store calculators. But how fast can they count; can they be used as tripometers on a bicycle, or more slower like for a pedometer, or fast enough to count windings on an electromagnet being unwound with a drill? Very neat though. Good enough for counting people through a turnstile or opening doors, etc. Love it.

[@WhoWantsToKnow81]

Interesting hack!

[@kevinbeckenham3872]

Very very interesting.

[@leifkeane]

Thanks!!

[@TwistMasterDeluxe]

Brilliant.

[@MrBrownstonee]

just type in 1+1 and press =, press +1 again and just keep pressing =, hey you've got a counter!

[@tmiller1916]

This would work well to measure how many times the blades of a windmill or wind generator turned by putting a magnet on the rotating device, a reed relay near the parameter connected to the calculator. The auto power off feature might be a problem.

[@karslake10]

Hi.. problem is that after five minutes not using the calc, it turns itself off !!!!!! think you can find this bug?....must by pass some cap somewhere....

[@VoidFame]

Dude, cool oscilloscope.

[@bnrchmp]

how can one disable the auto power off feature?

[@chass5438]

It may be easy for you, you know what your doing.

[@QbidMusicandMore]

Where do I get a magbetic Reed relay?

[@zakhan14]

Hi can you make a digital counter according to my needs?

[@Miister00]

ah okay this is very nice and all, but.. will it blend?

[@MrSlimak39]

Because of many deferent clalculators, how find equal contact places? I shall be very grateful for any help

[@shaurab007]

Hey I did all the step that you have done in the video but I was unable to make the counter. Please help me. Reply asap !!!

[@100roberthenry]

could i use a sausage instead of the relay..?

[@shivamsiyani8]

What is that black thing on calculator circuit and how to open it

[@babitamandal5171]

Display of my calculator has been gone plz tell me solution

[@longnhatking5408]

I can't find the two contacts! How to find them? You said this so easy: "having done this you'll find 2 …" Plz tell me how to find those contacts

[@Turbo_lover]

Long Nhật King Locate the physical button for the equal sign on the board.

[@Mr64YO]

how to find the contacts?

[@martinpalsson490]

+Mr64YO Locate the physical button for the equal sign on the board.

[@desinfector]

reed or red?

[@ballan1668]

reed

[@UncleFranco215]

hey can you put a counter in a boxing glove?

[@riyazshaikh8627]

Switch name

[@OmarSerra]

Cool nis ereewar

[@techfield5819]

it is made by calculator

[@sultana8107]

It is not working fast

[@SkazaTV]

wrong soldering !

[@neartogod4075]

Hello sir Mera ek project bna sekte ho Kya chota hsa hai fess aap ke 10000