Turn a calculator into a metal detector

I recently discovered a really cool method in using a few household items to make a HomeMade Metal Detector! Heres how to make your own!

Heres a link to the video : http://www.youtube.com/watch?v=_G5HzeIl9cY

Step 1: What you need.

All you need for this project is, an: AM Radio , some tape , and a small calculator.

Comments

[faisal rahmanp]

Very nice,what an easy way to make a ditector!

[chuckcrunch]

nice gag , the beeping is a give away LOL

[mayang06]

would there be a great difference if i use am/fm radio along with the calculator as my metal detector?

[ochoa10]

Maybe it works better with a calculator without cell?

[win nyunt]

I am very happy. I have not money.If have money,there is not eassy to buy this b/c of my country. I very thank to you.

[KevinAlien26]

Hey great 'ible even though u only found a spoon from a few inches away it's a good place to start :)

[Kiteman]

This isn't a metal detector.

Calculators do not emit RF at a level detectable by a cheap radio.
Calculators do not, in fact emit RF at all. Not only do they not contain a circuit that oscillates a voltage through a coil or antenna, they do not do not contain a coil or antenna, nor do they contain anything that could act as an antenna.

But, the clincher is this particular calculator's power source.

It's solar.

How does anybody expect the calculator to emit anything when the cell is turned face-down and held close to the non-reflective carpet?

What the poster has discovered is that lumps of metal brought close to a radio receiver can interfere with the EM coupling of the antenna.

Further scepticism stems from the double posting of the same video - anybody who reads the 'ible will view the same Metacafe video twice, doubling the income earned.

[RazorG606]

Hey Kiteman, I actually got this from a book called "Sneakier uses for everyday things". I made this video years ago when I was younger. I simply recreated what I seen on paper. Its fine that you're a skeptic but it does work. You can get a preview of the DIY on google books if you'd like.

[bbuuggmmeennootta]

"Calculators do not, in fact emit RF at all. Not only do they not contain a circuit that oscillates a voltage through a coil or antenna, they do not do not contain a coil or antenna, nor do they contain anything that could act as an antenna."

LCD (Liquid Crystal Display)
It is an electronically modulated optical device made up of any number of pixels filled with liquid crystals and arrayed in front of a light source (backlight) or reflector to produce images in colour or monochrome.

Modulate
To vary the amplitude, frequency, or some other characteristic of a signal or power source.

and here's some other pages for you to peruse:
http://en.wikipedia.org/wiki/Electromagnetic_induction
http://en.wikipedia.org/wiki/Eddy_currents
http://www.bukisa.com/articles/215991_design-of-metal-detector-using-the-induction-balance-system-application

[bbuuggmmeennootta]

Hey jack, "double posting of the same video" huh?? that's kinda funny cause one is the video, another is a link to the video. Are you really that thick?

"anybody who reads the 'ible will view the same Metacafe video twice" << It's a YOUTUBE video you tard. Sorry to break it to you but youtube users do not make money from people viewing their videos, they make money from clickthroughs on ads.

"they do not do not contain a coil or antenna"
Sorry but technically, anything containing any bit of wire, contains an antenna.


Sorry to steal your limelight, go troll elsewhere.

One final thing, if it doesn't work, why are there soo many results on google proving it /does/ work?

[Kiteman]

"One final thing, if it doesn't work, why are there soo many results on google proving it /does/ work?" (just over a million hits on Google)

If that's your criterion for belief, then you also believe in UFOs (220 million hits), Nessie (3.3 million), guardian angels (6.5 million), free energy (114 million), and that the Earth is only 6000 years old (22 million hits).

Have *you* built one?

You accuse me of trolling, when as far as I can see you only created this account to post insults? You really should have read the site's ToS before you signed up.

[dataphool]

Point of Order:

A mere 20 million UFO abductions ( picking up hitchhikers) could easily generate 220 million hits on Google. Did you ever notice, hitchhikers are never the scintillating conversationalists you expect.

Sonar scanning of Loch Ness, done several years ago, would detect Nessie; and didn't. Nessie has obviously died. after all, he / she's several hundred years old.

Earth is 6000 years old. There is absolutely no question. It is only 4.2 billion years older than that. Notwithstanding, christians are typically boring, they are the only thing wrong with God.

[daiatlus79]

doesnt anything that carries an electrical current emit some manner of RF signal?

[Kiteman]

The issue is the *strength* of the signal.

[daiatlus79]

that i agree with there.. and if the shielding is strong enough then it wont be detected. and well i doubt that the thing would react to metal the way that a metal detector would to illicit the same thing.

[jcrawfordor]

Simply not true - you can easily demonstrate RF emissions from a calculator with a radio. I'm using a Yaesu VX-5 (handheld ameteur radio tranceiver) tuned to 1.100MHz AM with a 1/2m antenna, and I can distinctly hear a low tone emitted by my TI-84+SE, which clearly changes depending by what is present on screen. It appears to be something related to the screen, likely the LCD controller, that is creating the tone. It appears that the calculator emits the bulk of this radiation forward, not backward, which makes sense, because there is a metal sheet just inside the back of the calculator which would block this weak signal. The directionality of the radiation suggests that this method would work, because the metal object would reflect the radiation emitted by the front of the calculator towards the radio, which is behind the calculator. I have not been able to observe this working in real life, however - I think the radiation emitted is simply too weak.

[GZNG]

there's a click to it... the calc he is using , like you said , is solar powered... then again it also has a battery compartment ...if so ,with all due respect... please explain why and how it really works...

[Kiteman]

Where did I say it works? As far as I can see, it doesn't. There is such a thing as audio editing.

[bbuuggmmeennootta]

Have you attempted to build this ? no? then you have nothing to base your argument on. Simply put, your spouting smoke where there should be fire. You have absolutely NO argument here besides "it can't work cause i'm a skeptic" which in truth, isn't a very good argument.

Try it before you decide to ignorantly dismiss it as false.

[kretzlord]

I hate to blow on this dying ember, but bbuuggmmeennootta, you are being incredibly disrespectful to one of the more prolific, and i daresay knowledgable members of the Instructables community. Sometimes people disagree, but before you start arguing like a child to prove your point, consider the other person's point of view. The great thing about this site is that nothing is taken for face value, we are all encouraged to try it for ourselves, and share our experiences so that others can learn from our example. Please become a contributing member of the Instructables community before you look down on those that take the time to make this site worth-while.

[Kiteman]

I appreciate the sentiment, kretzlord, but I fear you are shouting into an empty room - the member has not posted anything outside these comments, a year and a half ago.

[temp]

I havent tested it myself, but i just got a calculator today and there was a little not on the inside that said it may cause interference with radios.  So i guess it could be plausible.

[bbuuggmmeennootta]

Yes this is because everything electrical produces RF Interference. They put the note on that because it's the law, they must also attempt to shield the RF interference to the best of their ability.

Those that dismiss this simple concept are purely ignorant and will most likely never admit they are just plain wrong.

[Aburame Shino]

Crush the boy's dreams why don'tcha?

[nitram_cero]

How does anybody expect the calculator to emit anything when the cell is turned face-down and held close to the non-reflective carpet?

Most solar calculators also come with a cell. The solar panel is for backup.

"Not only do they not contain a circuit that oscillates a voltage through a coil or antenna"

The typical way to implement a keyboard is thru a matrix to minimize the number of pins needed by the microprocessor/controller for input.
In sequence, each copper track is turned on, acting as an oscillator (I'm guessing f=10k..100kHz) and the copper track is acting as an antenna.

Google "keyboard matrix" for more info, or enter here:
http://www.dribin.org/dave/keyboard/html/

Holding your PC keyboard near an AM radio should work too.

I'm not saying this works, but I'm saying that it's possible.

Cheers,
nit

[Big Bwana]

Kiteman, I have a calculator which has an internal antenna and emits lots of RF noise, but then again it also has Nixie tubes in it ..... And who wants to drag 30 lbs of metal (( Ya they made things like calculators from metal back then )) across the floor to look for more metal, but I guess you could drag it from the power cord if you like...

[ivanjacob]

WHY DO YOU GUYS CARE!?

[Kiteman]

Why shouldn't we?

[bbuuggmmeennootta]

And just to clarify before the trolls jump on this and attempt to disprove things based on one small formality..

http://preview.tinyurl.com/3ltb6ng

(you notice I gave you the preview of that url, that's cause I know how ppl are with redirector sites, so before you say Hurr Durr, just check em)

The TI-108 unit is solar powered and does not use a battery to power it. (from TI's knowledge base)

So no that calc in the video DOES NOT have a battery. Still, it is able to use the ambient light (carpet doesn't have to be 'reflective' for light to be available in the room, as a matter of fact, solar calculators require very little power) in the room to function.. How amazing is that?

[For Better Or Worse]

SergentLaughter, Try taping one or more of your calculator buttons down, that should do it ;) Oh ya, RazorG606, nice idea but it is already all over the net. Another Thing is that yes it is a metal detector, but the range of this project is too small for anything other than finding coins in the sofa and studs in the wall. But still, if you hacked the radio to give more reception and then put aluminum in the calculator, then put a faraday sheild in between the two devices, the range should increase enough to match a full scale one. P.S. If you try to make the excuse that I do not know what I am talking about, you should know that I did your project a billion times (maybe not a billion, but close enough) and I'm a jack-of-most trades. Meaning, I can make or repair ANYTHING you can THINK of. So that being said, hope you take my advice, at least with the faraday shielding. That should make the most diference in range. I hope by the time you get to the end of my comment, you do not take offence of my p.s.. You see, people seem to think i'm stupid and a was just clarifying the reverse of that. Hope to talk soon, For Better or Worse

[Riptide100]

Lol, right next to your JACK OF MOST TRADES(who can fix anything on god's green earth) award you can put your humility award as well.

[jon-ecm]

Thanks for the good info.
I published a website that has guides to making a more advanced pulse induction metal detector based on the same technology found in minelabs gpx series gold detectors. It's really easy to build and I'd defiantly recommend it to someone who has some electrical skill.
http://www.miymd.com

[rscott-2]

Ahahahahaha! I love the world sometimes. My son happens to be watching an episode of Curious George with this on it when I stumble to the page.

[peterkharofeh]

thx alot

[aqwiz]

Wow, I didn't know the OP was an Alot. That's really weird, I didn't even know the Alot species was capable of intelligent thought.

[chemicalvamp]

Wow, thats clever.

[riverreaper]

do studfinders work the same way?

[For Better Or Worse]

Oh ya, RazorG606, I forgot to mention that if you are interested in stuff like this, Try Making my analog Transmitter from random things. It needs some improvements, like faraday shielding. Hope you leave plenty of comments for me.. One other thing, if you do not know what a faraday shield is, it is usually a steel sheet or mesh that is grounded to the negative of the battery terminal or is earthed. Hope this helps. For Better or Worse...

[iloveemogirls]

amazing im trying this out

[FFVIIBOY]

Well i just need to get a calculater and a AM radio or watever its caled and try it out. ill tell u wat hapens wen i do it :)