EEVblog

How to hack a calculator into a test system event counter.
Previous video on contact debouncing and using a universal counter: • EEVblog #961 - Monkey ...
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[@zer0b0t]

Hacking anything, that's the kind of content I really like to see.

[@zer0b0t]

Ugh?

[@thelavian4481]

You often tell random people what to do?

[@arcade_signal]

I think he meant hacking in the original technical sense and not in the "soft" sense where the word has been co-opted by morons and applied to silly stuff. It's even been bitten by marketing people, search for "growth hacking" to discover a new and exciting world of idiots

[@electronicsNmore]

I did the same thing using one of those inexpensive tally counters. Worked great with the magnet and reed switch.

[@PiratCarribean]

I read "Hacking A Calculator Into A Calculator" 😂

[@anotherdayisforever]

One of my favorite DIY vids youve ever done!

[@NoxMarcus]

Dave is SO prepared to demolish the Batterizeroo. Got all the toys lined up, I love it. I don't care about the actual device itself. But all this stuff showing how to accurately disprove the b.s. is really interesting.

[@linengmiao]

More of such hacking video's please! It is a real pleasure to see you hacking/modifying and reverse engineering stuff (in stead of mostly just analyzing and explaining like we are used to).

[@orvillejones1258]

Nice project Dave, thanks for sharing!

[@kryskarr23]

Cool tutorial. Big fan. Take care and keep up the quality work.

[@NicholasAarons]

That Was Awesome Dave. Keep up the great work. Nick.

[@DoRC]

batterizer test setup!!

[@samgab]

PS, you can also hack a cheap pedometer to do the same thing as this. They just have a little weight and switch inside which increases the count by one ever time the weight moves and closes the contact. You just remove the weight and solder wires to the two contacts and then you can connect those wires to any switch, such as a reed switch and magnet or a light sensitive switch, etc.

[@mattshilling]

Samgab Better solution!!

[@rpc72]

Samgab was gonna post the same comment when i saw yours.

[@Blendedasian]

holey queen spikes, look at this fabulous smooth footage! Thanks, dave, you're making your videos way more pleasant to watch with 50fps. welcome to the pc master race club.

[@TechGuyCharlie]

Hi Dave, such a cool project there! Would have looked great with a VFD display calculator.

[@tambechristian]

You are a genius Dave !!

[@mbirth]

I somehow expected you to seamlessly implant a calculator into a counter top …

[@rogerkerr5745]

I saw this done by a couple of guys who wanted to count the number of turns when winding a motor. It was a brilliant simple hack which performed perfectly.

[@nickhill9445]

Love the idea. Another possibility is to put the reed switch inside the calculator case. It can read the train directly without affecting the calculator appearance, and you can use a solenoid placed near the calculator for other applications.

[@ExStaticBass]

This is definitely something I wouldn't have considered doing before watching this video. They say the simplest ideas are the best and this one is brilliant. I think I would put the connector in farther so the pins wouldn't stick out the side but that's the only thing I'd change. I loved the Keysight O-scope hack too which I just finished watching before this one.

[@BendeVette]

I used this when I was 18 (34 years ago) on my bicycle to count the distance of my trip. You could enter the circumference of the wheel and each rotation would add this to the previous result. Worked wonderfull. Magnet and a reed relay.

[@MyBigThing2010]

this is genius....I would never thought to do this on my own...I'm not that "creative" ...thanks for the idea, just saved me an eBay purchase, saved money and a month of time waiting for CE garbage to get here...all for the cost of a jst, a scrap of wire, solder dots and a few minutes of time! definitely gonna give this a go! THANKS AGAIN.

[@thevoid7480]

Forshadowing the batterizer test setup. ;) But why not use an arduino for that? You can collect and store the data and send it to a PC. Then you could also implement a timer that measures how much the train slows down instead of just counting loops. Collect more data!

Great post Dave!

[@andrewsalton7670]

simple,cheap and reliable. nice one.

[@TechsScience]

This videos deserves millions of views

[@umajunkcollector]

happy new year dave, good one Don

[@danielmoraes9637]

Great job!

[@tomwimmenhove4652]

I remember doing a project like this when I was around 6 or so. I connected one wire to our (aluminium) sink, and the other in a glass of water. By placing the glass below the tap and having it drip into the glass, the calculator would count the number of drops that have fallen. At the time I didn't appreciate the incredibly small change of current by the charge carried by a single drop. I'm still amazed that it worked at all :)

[@abymohanan2043]

Thank you so much for this video 👍🏻👌🏻✌🏻

[@billboe9784]

Great video! Ive never seen a hardware calculator hack before.

[@doggy_888]

WOW it's a really cool project!!!

[@faybercova]

what amazing video, congrats

[@ralfgottfridhansson3127]

Nice battery tester ! Happy new year!

[@aserta]

I used one of those electronic finger counters. Works perfectly well for those who don't want to do complex things.

[@RinconingenierilEsp]

I love it, thumbs up

[@ravivashatkar5585]

I had the same idea Dave .... I never tried it .. thankyou for doing this 😊😊😊👍

[@genericgreensquid6669]

This was helpful!

[@shawn_2]

Super cool!

[@krzysztofsoja5301]

Back in a days I used this method to make distance couter for my bike :)

[@travis4798]

I use to mod electronics in the past. Best wire to use for pads is computer ribbon cable and if you go online to say Amazon they have ribbon cable by 20-50 foot rolls. Solder on with low heat, tack down in a few spots using hot glue, it will never come off.

[@fdjhrfgjry]

Hey Dave, another great feature of this ghetto-counter is that you can determine the +1 amount so flexible, eg. if used in composed counting formulas and tailor them (other than 1;) to match your purpose or eg. 6 decimal position or better precision. Almost literally a streetwise universal counter ;)

[@SlyPearTree]

I used that trick to make a cheap digital voltmeter in the 80's. If I remember it counted how many fractions of second acapacitor needed to charge from 0 to the same level as the voltage being measured (or discharge from measured voltage to 0). The fractions of second were probably relatively large since the calculator could not respond that fast, that was probably due to internal debouncing of the keyboard circuit. I think I took the idea in a magazine. The result was not really seriously usable but made a nice little experiment to learn a bit more about electronic.

[@Zamsky39]

I really like videos like this one.

[@bornfe5127]

wow now ive got a counter for inductor and transformer projects thanks dave ("beauty')

[@welshgoldferret5107]

Awesome, I remember doing this when I was making Tesla coils on my homemade winding machine, worked well.

[@tonesoft1956]

New this when I had my first Casio calculator in the late 70s :D

[@RPBCACUEAIIBH]

If you press "+" then "1" instead of "1" then "+", then it starts from 0 not from 1 works the same way. You can also type in an initial number, from which to start counting, then "-" and "1" to count down, you can also use another numeric constant instead of "1" to count by that numeric constant.

[@horiamorariu]

Genious! Just remainds me that in a very old TEHNIUM (Electronics Magazine), back in 1980, in Romania, there is an article of WINDING MACHINE COUNTER - exactly the same, but based on Texas Instruments TI30. Nothing new under the sun. But maybe for some young hobbysts is new. Cheers Dave!

[@88njtrigg88]

Can be used also for a home made anemometer project, with the addition of a stop watch.

[@mirkomueller3412]

Nice Idea - might come in handy someday.

[@waynerussell6401]

I had a client who wanted to detect how often a reference book was used. I embedded a watch module in the spine with reed switch and magnet and mode to set minutes. Only counted to 60 but that was adequate.

[@techalyzer]

I have done this on my bike ages ago, only instead of 1, I used to put in the tire's circumference to measure the distance.

[@mooncabbagere]

This week on EEVBlog's The Dave Jones Show, Dave hacks a calculator to count automatically!

[@antonnym214]

Very nice! We can get these calculators at the Dollar Tree (everything's a dollar), so this is an awesome use for one.

[@MrJohn1966elliott]

In 1984, I build it, use for "Odometer" fit my push bike. I put magnet on spokes bike wheel.

[@SimonE-fz5pc]

Funny found a box recently in the attic where my father did the same thing to count ants in a tube leading to food with a light switch for his Dr (PhD) thesis back in 1974! Sure it was an old "4 banger", as Dave says, but it still worked and high tech back in the days.

[@JONOVID]

IMO I would use hot glue to anchor wires in place. also I would use sockets as the wires end connectors so you can close the back up on the calculator and re-use for other counter type jobs in the lab.

[@Zadster]

Doesn't the calculator have an auto timeout? Unless you are watching it all the time, the little train will eventually stop, the key presses will cease and a few minutes later it will time out, losing the count number? The M+ button might have been a better option, as the contents will be retained.

[@EEVblog]

Good point. No issue for me as I'll be recording on video.

[@therealjammit]

I'm sure you could either buy enough cheap calculators until you find one that doesn't time out, or buy an old LED calculator on eBay. Pretty much any old LED calculator didn't have enough horsepower to do fancy things like power management. Might have to make an Ac adapter to replace the batteries.

[@akuunreach3260]

Nice Zadster, I was going to comment on the M+ being a better way as it keeps a perfect count vs the +1 Though Dave could just start with -1 so that the running total comes out correctly.

[@suplerb]

Zadster Whatt does M+ do?

[@akuunreach3260]

Mancobbler, it adds to what is stored in the memory. MS is memory store, M+ and M- add and subtract from the stored value, and MC clears the memory. So say you want to figure your pay but part of it is over time, so you take your hourly and multiply it by 40, and store it in memory. Then you would take your pay and multiply by 1.5 or w/e and then the hours of OT, and press M+ Now when you press MR (memory recall) it will show your pay for the week before taxes and withholdings. If you already knew some or most of this, I was simply trying to be thorough, plus others might read this post.

[@inderpartapsingh4445]

great sir

[@MisterTalkingMachine]

We used to do calculator adding races in school this way.

[@dheujsnrhfydhehehshshhdggsd]

really enjoyed a simple kid friendly project

[@tzisorey]

I had a calculator as a kid, that had a little thumb-trigger "Count" button - so you could take tally of things easilly. Had one of those old light displays on it too - doubt it was LED, but some sort of low-power red 7-segment things.

[@Luclips123]

Thanks

[@magista247]

I did exactly the same 35 years ago with a Sharp calculator on my bicycle to measure the precise length to the basic school ;) So i was the first to have a 'bike computer'...

[@petermuller608]

Having a toy train: nerdy Using a calculator to manually count the laps: nerdy Hacking the calculator to count the laps of your toy train: king of the nerds xD

[@dismayer666]

genius in simplicity :)

[@user-vx8wr8wn5z]

Very good seeing in Brasil 😮

[@tasteless_5915]

If you get a knife down the middle of the plastic heat rivets you can “drill” them out as it separates the outer ring from it and you can’t take the chip out.

[@frogz]

heres a little hack for you, 301 green laser pointers(or any other cheap 18650 green laser pointer) aimed behind the board lets you see right through most circuit boards to see the traces

[@kajyakuzonik9130]

Awesome! :D

[@moustafa19997]

nice idea

[@brainndamage]

I've used this method before for counting turns on a coil winding machine, the problem is that the calculator can only count so fast until it starts missing pulses. But for slow counts it is ideal.

[@SpikesMavic]

Fantastic, just what I need, am wanting to count the amount of turns of wire for a transformer

[@vehasmaa]

i knew about constant mode but newer tought one could hack calculator to do it like that... Sure gives new usefulness to bargain bins 4-function calculators...

[@Eicles]

Annoying that there always has to be some dislikes; this is bloody brilliant! I'll have to remember this one, might come in handy! :-)

[@BlankBrain]

03:29 should'a used your Crocodile Dundee knife!

[@jimc52]

you are a genious.

[@ryangriggs5767]

Very nifty idea! I wonder what the maximum input frequency is? (probably some multiple of the key matrix scan rate?)

[@didierdubos]

Hi, In order not to have to substract one to the result, just substract 1 to 0 then add 1 and press twice + key. You then start from 0 cheers

[@danielpare9129]

You could also start the claculator with the value (-1) + 1. Then it will be set to Zero and no need to substract 1 at the end.

[@giga-chicken]

I actually wrote a python script for a raspberry pi to do this, but it does more than count, it also records the exact time of each lap so that a time line can be drawn for the entire experiment. The result is a somewhat gigantic text file which I feed into a java applet to generate a pdf.

[@MisterBadNews]

This is how we used cheap calculators back in '90 to count the number of coils on homemade coil winding machine. Using a calculator, a magnet and a reed switch attached to =.

[@SurajGrewal]

plus since it was button input to begin with, it has debounce

[@TheBendixSA]

Dave if you do some simple math and start the calc in constant mode with the right amount added, then that becomes a distance counter without ANY modifications. COME ON GIVE IT A BURL!!!

[@Andrew_Sparrow]

ive used the cheap dollar store step counters in a similar way, even easier to hack :)

[@Jones12ax7]

as a kid in the 90s I used a crude switch on the front wheel of my bike and a hack like this. I type the wheel circunference, 2.1 at a time, and + so the I could measure the distance. I even placed a switch in a shoe to make a pedometer for a science fair of my schol. Good times before the microcontrolers invasion that we like so much today.

[@EgoShredder]

My uncle and I did something similar to make a digital speedometer for my bike around 1980 I think. We used little reed switches near the wheels to measure the speed etc. It worked perfectly and I was a proud kid, with lots of DIY gadgets! Good times :-)

[@nrdesign1991]

I made a bike pedometer that uses the AC voltage coming from the hub-mounted generator as a signal. It can't charge its battery through that yet though. I don't have any plans on working on it at the moment.

[@maicod]

as a kid I had a Fleischmann train and used 2 metal strips that when the train ran over it were pressed down and so the circuit closed and I let a railroad-switch flip over

[@tin2001]

I did the bike distance counter thing when I was a kid too. I wonder if I still have that calculator somewhere....

[@kaziq]

I once taped a switch (just two flat metal plates) to my heel, and wired it through the sleeve to an old bike counter stripped to my wrist. Then set an average step distance as the wheel circumference in the counter, and had a crude distance counter. And it was painful too after some time with the swith on my heel.

[@billl605]

Go green, power the loco with a solar cell, great video, and a thumbs up.

[@KrazyContraptions]

I'm gonna make this but connect a binary counter circuit to it instead of the calculator. It will be fun!

[@gorillaau]

Nice that the troll doll came along as a witness.

[@FennecTECH]

I would use lego and an solenoid to simply push the button each time lol

[@RyanUptonInnovator]

you forgot duct tape.

[@FennecTECH]

dont need duct tape when you use a lego flatboard as a base

[@RyanUptonInnovator]

I will attack your lego flatboard base with my duct tape x-wing fighters. Prepare your exhaust valve for my proton torpedos.

[@FennecTECH]

that sounds painful

[@RyanUptonInnovator]

At first it is like ow ow ow, but then it is oh oh oh. The worst bit is the child support.

[@jschroedl983]

OMG I loved those thomas the tank engine tracks

[@KevinOsborne1987]

Joe Schroedl AKA 'Brio'

[@johnrickard8512]

A TI-83+ series calculator(NOT the 84+CE) can be hacked in a similar way using its link port(actually, it could be made into a dual counter)(I should also mention that TI was aware of this when they made the CBL2 equipment interface, which can also do this).

[@brianhoskins1979]

Nice. As a point of interest, I would have liked to test it on a signal generator just to see what the maximum counting speed is. Not that it matters for your application, just a case of "well, I've built it... but for fun let's see how fast it can go".

[@ge200099]

Neat!

[@LA6UOA]

Cool! Thanks, Dave! I really don't like tape. it falls off and in time its glue is a mess. Is there a reason why not use hot glue? and how fast is the calculator? Can it be used to count the rounds of say a propeller on a model aircraft? Love your channel!!

[@tehaxor69]

You could of used a TI 83/84 with a arduino as a remote. These calculators already have a built in ROM Call for remote button presses via the link port. You could write a TI Basic program that scans the getKey var for a increment and reset button press.

[@graceful_songs]

it's the first time I knew that the holes in the pcb are test points .. I was wondering so much but couldn't know what to ask ... ahh thanks alot

[@Tom.N]

Nice.

[@xitman327]

for a monent i though i watch kipkay here! haha you got me dave.

[@mescalinum]

Very clever trick! Thank you. Would using an OTA (like the LM13700, which has an example for voltage-controlled resistor) do the job for triggering the "=" key with a digital input, or it is an overkill? Perhaps you could achieve the same with a MOS?

[@0youwannagethigh0]

fun hack !