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Welcome to the Instructables Teachers Hub!

Welcome to the new home for all things Teacher related on Instructables. We hope you'll explore the new features and come back often to find and share projects, inspiration, and classroom resources. As you explore the new Teachers Hub, you'll see it's easy to find projects by subject or grade level and sort them to find all the best and freshest projects.Be sure to spend some time in the new Teacher Forum. It's a great place to connect with fellow teachers and make new friends! You could start by introducing yourself here or finding a topic that interests you and join the conversation there. :)We'll be working to continuously update and support your needs in this new area of the Instructables community, so thank you in advance for your valued feedback and suggestions.

Topic by WeTeachThemSTEM    |  last reply


Welcome to Instructables

On this page you can find links to some of our most frequently asked questions. What is this site? Instructables is a community for people who like to make things. Our community shares what they make in a step-by-step format that we call an Instructable.How do I post an Instructable? We offer a free and easy online class to coach you through posting your first Instructable or you can just wing it and start a new one today. How do I get help improving my Instructable?Ask the community for help in The Clinic. How does my Instructable get featured? The best way to get your projects featured is by following the Featuring Guidelines. Where can I learn more about contests? Our Contest FAQ has all of the information that you need to know about contests. What contests are launching soon? Check out our list of upcoming contests. Are you on social media? Yes! Follow us on Pinterest, Instagram and Twitter. How do I contact Instructables directly? The best way to contact us is through our Contact Page.

Topic by randofo    |  last reply


What kinds of contests do YOU want to see on Instructables?

Hi everyone! As we're planning contests for the next year, we wanted to get suggestions and feedback on the types of contests we're running. :DIs there a contest we ran years ago you'd like to see again? Any contests you're sick of? A weekly challenge you'd like us to expand on? Do you want the contests to be more specific or more open ended?We're trying to shake things up in contest-land - so any and all suggestions are welcome! I'm especially interested in what types of tech contests you guys would like to see, as well as ideas for food contests. P.S. For anyone wondering about weekly challenges - we're still trying to figure out a way to do it that makes it easy for you guys to enter and easy for the editors here to run. But I promise we are discussing it! :)Have prize suggestions? Check this topic. Want to get a preview of some of our upcoming contests?

Topic by randofo    |  last reply


The Clinic // Get help with your Instructables!

Hello and welcome to the newest version of The Clinic! If you have an instructable that's not getting the attention you think it deserves, post it in the comments below for honest feedback and suggestions to improve it from fellow authors and Instructables staff. We want to help you create the best instructables you can! Curious about the basics of creating an instructable? Check out my FREE How to Write an Instructable Class! You can also read through our Featuring Checklist. Posting a great instructable has many benefits, including:More viewsMore comments and followersHaving your instructable Featured on the site Having your instructable featured on our social media accounts (Facebook, Instagram, Twitter, Pinterest)Better chance to win contests Driving traffic to your websiteP.S. While I know the goal for any instructable is to get Featured, it's not the end goal here! We're sure to hand out features, but please keep in mind not every instructable is feature-worthy. Even the most popular authors have unfeatured instructables! Don't let it get you down - you're still amazing! :D

Topic by jessyratfink    |  last reply


Want to build a automatic opening drawer? Answered

could i use a dvd tray as the actuator if it is under a light enough load? what is the max it could probably open? thanx for any help you can offer

Question by JustinJalapeno    |  last reply


Any way to block a central computer from screen-watching me at school?

So the good old school library bumped up its security this year - you know, cool wastes of money like biometric scanners. Now, while I giggle every time I check out a book, I can't even bring myself to browse the internet. Never mind the fact that the school seems to be running IE's grandfather  for a browser (we just got tabs last year). Never mind that we as a junior class finally discovered the joys of caching, and that last year someone seemed to have started running Firefox off a USB to download mario games to the desktops. Our efforts have been in vain. All the library's computers are now linked to the central computer, so that the librarian can watch about 12 screens in real time simultaneously. She just sits there and watches your screen. Shoot me now. It's really not a big deal, as I normally only do legit research in school, but now I'm curious - is it possible to trick the main comp? Like, somehow running Firefox from USB invisibly if I have the bastardized IE up on the side? Or do I just save anything deviant for unsuspecting teacher computers?

Question by dumplings    |  last reply


Can I hook a home theater subwoofer to my cars stereo system?

I have a 1999 Jeep Grand Cherokee Limited with an aftermarket Jensen VM9512 in-dash DVD receiver. Can I hook up my subwoofer (Sony SA-W2500) to the receiver and use it successfully? I don't want to buy another sub. What I have to work with is a long enough cable to connect the sub and the receiver and a 12-volt DC - AC inverter. I'm not sure if the 12-volt plug in the back of my Jeep is turned on and off with the ignition or not, but the subwoofer has an automatic on and off mode and the power inverter is just ether on or off. Help? :]

Question by mooseman93    |  last reply



Replace LED indicator on charging pack of cordless drill

I have a B & D model RD1440 cordless drill. I recently had new cells put in the battery pack and it works great. My charger is FS14C and it has an LED charging indicator light which no longer lights. I would like to know the correct specifications to replace the LED. Can anyone tell me what is the proper replacement part and the correct way to replace it?

Question by guitarzan214    |  last reply


Ping pong ball launcher

Hi everybody, i need some support in developing this circuit.I'm making a ping pong ball launcher and I just need a servomotor with a switch and 3 dc motor.One should move quite slow and I wanted to use a potentiometer. The other two move together or alone but at the same speed. I want to control the 2 motors and the servo with Arduino. I don't know how much volt I should apply. Should work this way?May anybody give me some hints? Thank you so much.If u may want to change something https://www.tinkercad.com/things/aPDSlGBukDM-epic...I left here my code: #include Servo servo_2;int counter;void setup() { pinMode(8, OUTPUT); pinMode(10, OUTPUT); servo_2.attach(2); }void loop() { digitalWrite(8, HIGH); digitalWrite(10, HIGH); for (counter = 0; counter < 10; ++counter) { servo_2.write(45); delay(3000); servo_2.write(0); delay(3000); } }

Question by vincenzoga    |  last reply


Is there ANYTHING I can use old dial up modems for (other then dialing up the internet)?

Any old, or unique ideas on what I can do with them?  I have one that is fairly fast (an old cable modem) one that is medium fast (an old DSL modem) and one 56k plain vanilla dial up.

Topic by Goodhart    |  last reply


"Meow", the joke that never gets noticed!

    Okay, the joke I am going to be showing you is called "Meow".  It was invented by my brother in 8th grade, and it is absolutely hilarious! Oh, and by the by, you need to be able to keep a straight face for this joke, or it will not work.     So, the joke is very simple. You just insert a subtle "meow" into your sentence when you are talking to someone.  Example:     "Hey, man! How are you doing?"  "Oh, pretty good, meow."  "That's great."  "So, meow, umm, have you heard of the concert coming to town? meow."  "Yeah, I've heard of it."  "Are you going? meow."  "No, I can't."  "meow. Well, that sucks. meow. Well, I'm going to the concert. meow."  "Well, see you later, I have a bus to catch."  "Okay, meow. See you later!"      It really helps to make the pitch of the "meow"s to be the same as the sentence before or after.  My brother had to do a speech in front of the class, and he said "meow" FIFTY-TWO times in the the speech, and nobody noticed!

Topic by eulaliaaaa!    |  last reply


Can I use 60ppi polyurethane to filter solder smoke?

I am going to make myself a little rig. Two fans with some kind of filter sandwiched in between. I was wondering if polyurethane filter would work because I saw it and it was extremely cheap. 60 ppi seems like the best filter quality I can find. Then again I don't really know what I'm talking about. If someone could explain to me why this is a bad or even a good idea that would be appreciated. Also any recommendations on anything else I should use instead. :)

Question by Inblackandwhite    |  last reply


Anode and cathode metals? (For electrolysis)

I want to seperate some water to get Hydrogen to play with, so I made a little electrolysis device with a 12v power supply. The only problem is that I have no idea what to use as the anode and cathode! Could I just use screws? Or pennies or something?

Topic by Login258    |  last reply


Rate My Drawing!

This is a portrait I drew of a friend of mine. It took me about 2-3 hours to complete. Please tell me what you think, thank you :)

Topic by FoxyPenguin94    |  last reply


which is the positave terminal on a dewalt 18 volt battery?

Dewalt battery terminals are not marked, I need to know which is which

Question by popop1111    |  last reply


Internal server error. I'm alone

After 4 days to try to upload a file i have always an internal server error message. How we can fix that ?

Topic by Yannick99    |  last reply


Legal and copyrights confusion.

Hey everyone, I love instructables and I've been working on my own tutorial for the last few weeks. I am not far from publishing the instructables. Recently it came to my attention that I might have some legal/copyright issues. I built my DIY using some parts I took down from other products that are still on sale. One of these parts is copyrighted but not patented. I was wondering, due to the DIY and instructables nature if that would be an issue for me? I am not reselling the DIY or pushing people to do the same as me and even give indication to future makers about how to obtain that part legally. I cite all the sources of the original product from which I borrowed the parts. Would it be ok if I publish my instructables like this or should I avoid talking at all about the "borrowed" parts? Also, if a newspaper or magazine wanted to publish an article about my instructables, would granting them sole publishing rights interfere with using the "borrowed parts" that I talk about above? Would I even be able at all to grant them these rights, given the general terms of the CC license (Non-commercial share-alike)? Does this CC license allow anyone to publish an article about my instructables without my written consent (print and online), so long as they cite the sources? Thanks in advance for helping me out, I'm a bit confused!

Topic by twinbirder    |  last reply


CDROM Motor as a USB Controller - Is it possible?

I would love to see a USB controller made out of a CDROM motor. I have seen projects the other way around (powering a CDROM motor via USB) but would it be possible to use one as a controller? My electronics skills are very basic so I have no idea where to start.

Topic by DaddyWio    |  last reply


L298N - NodeMCU / D1 Mini - DC motor 12v

Hello,I am new in this area. I am struggling to make a dc motor to work forward and back with 2 buttons a L298N bridge and NodeMCU or D1 mini. I look every where on internet but i dont find a good example to help me. Please can somebody help to tell me how to connect all this toghere and if is posible the code ! I am all ready strugling for few days with this :( .

Topic by eduard_niculita  


Elementary School (K-5) Teachers

Do you teach at the elementary level? If so, this is the place for you to introduce yourself and connect with other K-5 educators. Where are you from and what grade level(s) do you teach? Say hi and share something exciting you did with your students this year or project ideas you have for next year. :)

Topic by WeTeachThemSTEM    |  last reply


creating a surface in Invesalius?

Hi there! We want to produce an stl of a heelbone from DICOM files to print and use in an operation. The edible Chocolate Brain was the inspiration to use Invesalius - meshlab I already know so this seemed like a good option. there are, however, limited manuals in english and infos to figure out certain steps in the Program ... like creating the surface for the stl - the mask has already been taken care of and everything else looks right, just this one step isn't yielding the expected result. a link of the document in question to look at - https://www.dropbox.com/s/3oinuz5goz15mws/Fersenbein.inv3 I would appreciate any help a great deal. thank you & snowy regards from Vienna, Eva Tucek

Question by evatucek    |  last reply


Some advice on hacking old phone parts

Hi there. I've been playing around with repurposed items for a while now. But, I've come to a standstill on my latest project. I have a few old smartphone spares. I live in a commune and my room gets looted often. I dont have a pc, but i do have a tv. Im looking for a pinout diagram of a phone cam, so i can wire it with some cat5e cable, into rca, and into my tv, which in turn, is hooked up to an old vcr that can still record. Can anyone help me with a diagram please? My food goes missing. I lock my door, but someone keeps breaking in. Thanks

Question by celticphoenix69    |  last reply


Please help me identify this Silver signet ring

Found it stashed away in my grandpa's house after he passed, he was a polish immigrant, so it might be from there

Topic by lauracz62    |  last reply


Has anyone ever built their own rooftop luggage or cargo box?

I have had a couple and for 2 & 300.00 bucks or more, there's really not much to them. It's just a hollow hinged plastic box, made to be a little aerodynamic and strapped to an existing luggage rack. I find it hard to believe that a home made version couldn't be created as sturdy if not sturdier, hold more and last longer. I was thinking maybe pvc, conduit, or even wood framed. Just curious. Thanks in advance for any helpful input.

Question by SAWWAS72    |  last reply


Tesla coil/Slayer Exciter not working! PLEAAAASSSSEEEE HELLLPPPP! Answered

I have been working on a tesla coil/slayer exciter for a couple of months now, and recently did my first tests, which didn't work, and I couldn't figure out the problem. above is the pictures of the breadboard my circuit is on, the coil itself, and the schematic I based it on. Instructable that I used/followed

Question by Cheesey125    |  last reply



Wireless Radar

I am trying to make an arduino based 360 rotating radar system ..the issue is entangling of wires and to resolve this i want the arduino to send data of stepper motor and ultrasonic sensor to processing 3 wireless via hc05 bluetooth module ..what all changes will be required in the arduino sketch and the processing 3 program to make this happen ..if anyone can provide me some link or material on the same ... i am using an already made instructable to make the radar.....i just want to change the radar to a continuous 360 rotating wireless system i am using 28 byj stepper motor with uln2003 driver ,hcsr04 ultrasonic sensor ,hc05 bluetooth module, processing 3 ide for radar output

Question by mukulmagotra98  


Why should perpetual motion be impossible?

Our laws of physics are quite clear when it comes to the impossible.You can not produce more energy within a system than what actually goes into it.And since friction will always be a thing in our real world perpetual motion is simply impossible.With this or quite similar reactions all good scientists end the conversation.We know it is not possible, so why bother...If all that is stopping are laws of physics, then it is time to redefine "perpetual motion".Another term for it would be "free energy" as we would have to draw energy from nothing to keep it moving.Solar cells provide free energy the same way as wind- or hydro generators, we even use waves on the ocean to produce electricity...Perpetual motion seems to be defined by mechanical things and motion only.And free energy seems to be defined as bogus only while ignoring the realities.We simply can't use the same terms for everything if they are in fact totally different things....A motor running off a solar cell would be a perpetual motor if you widen the energy term a bit here.The impossible energy to run the motor comes out of nowhere - our solar cell generates electricity from sunlight.And a simple water wheel in a stream will power a mill for as long as water runs down the stream....Humanity and science say this is not free energy as we take energy from other system to make it move.And of course it is a dead simplification anyways.You get the picture though.So far humanity has only managed to tap into a very few forms of energy out there in any direct form.Solar cells come to mind first of course.In a way they utilise radiation to transform it into DC electricity.Then we have all sorts of mechanical energy transfer, from generators over windmills to the modern recovering brakes in electric vehicles.Last but not least we have heat, steam engines, nuclear reactors and so on.The laws of physics however know a few more forms of energy....We seek out new ways to "generate" more electricity than ever before, like fusion reactors.What we don't seek is understanding what we always had already.All we do it to try to "generate" electricity.It is what powers our world but it is only a tiny fraction of what is possible.We burn fuel in a comustion chamber to make piston go up and down.Only to transfer this motion into a rotary one to finally drive our wheels.Most of the energy available in the fuel is wasted this way.Making it slightly more efficient took us over 100 years....Thinking about using the fuel more directly does not even come to our minds.So why bother to consider any other possible form of energy to drive our world.We are stuck in definitions no one really understands because most of the used terms have more than one use and meaning.We fail to open our minds to other possibilities just because "that's how it is and always will be".Flying to the moon?? Impossible!We did it anyway....Using batteries to provide electricity to entire towns? What a joke!In South Australia they do it anyway and with great success as well.Powering entire cities just from wind and solar energy? Are you joking?Well, companies invest an awful lot of money here and they wouldn't do so if it would not make massive profits...So why again should perpetual motion be any different?At some stage it was hillarious to even think our world would spin around the sun.....

Topic by Downunder35m  



How can you divide an mp4 file into individual clips of mp4's?

I have an extremely long mp4 I need to use parts of for a project, but I don't know how to divide the clip into parts.

Question by RedneckAsian    |  last reply


Flc100 magnometer

Hi, can you launched sensor fluxgate flc100 magnetometr with ardunio and conected to pc wiht bleuthos? thack you very much

Question by parisa2000    |  last reply


Tesla's earthquake machine - was it just a practical joke?

Nicola tesla, in his early years, was not shy when it came to use science through direct contact.Most of it we would call today playing practical jokes on students and friends alike.His harmonic balancer got the nick name earthquake machine.I won't go into the story how all came together, you can read the story on Wikipedia or other sites to the fullest of your imagination.Howver, I would like to go into some details of this invention.Or better: I will try to explain my view on why this machine might have actually worked close to what the story tells....Studying old paents and other documents is no fun and not always you can reach any valid conclusions from any of it.I mean, if you coud then you wouldn't need a patent for it.Some things however are so good, so special that they never get a patent, the company keeps it as an iternal secret.Same way a brewery won't tell you the exact recipe for the beer they make ;)The harmonic balancer has very little to go with except stories and some comments Tesla scattered here and there.So let's start by some claims Tesla made about this machine:1. It has a free swinging mass.2. The mass is balanced using "air springs".3. It usues very little energy.4. It finds the harmonic frequency of the object attached to automatically.If you think about the above you could say right away it is bogus.But think about the terms and language of the old days ;)Add the fact that Tesla never really gave any direct answers to how his inventions actually work and you see where I am going here.Point 1 and 3 are easy to imagine in many ways.Number 2 on the other hand contradicts itself at a first glance.But, if you place a piston with a good mass and good seal into a cylinder nd close both ends while the piston is in the center....A bit like these to shake emergency torches and flashlights.With that idea in the back of a head one can imagine shock absorbers and more.And a "mass" "swinging" in such a sealed tube would certainly be subject to the "spring" force of the air being compressed in front and the forming low pressure on the other end.The last one however had me stumped for almost two years with me getting nowhere.A mechanical system can't adjust itself to the harmonic frequency of anything....Then I saw a collection of funny videos.One of the clips had about 100 metronomes standing on a board.The board was place on two rollers so it cold move freely from side to side.All the metronomes wre set to about the same timing.But of course you just can't start them all at once or even so they swing in sync.After just a short while though, one by one found a matching partner on the board.Faster ones slowed down, ones totally out of sync seemed to miss a beat here and there.And then it hit me!Hundret swinging masses on a board and the board moves together with them!Once all were in sync and harmony the board moved basically exactly the same way sidewas as the single pendulums above.Number four finally solved :)How though could one try to replicate this impossible invention these days and without knowing any exact details anyway?We know it used one or two electromagnets.These moved the mass back and forth horizontally in the machine.However, it was more formed like a T wih a fat base.Tesla needed a dead simple way of doing with electricity what the metronome does just mechanically.If you have a little mass on a spring and one contact on the spring plus another on a tube that is around the mass - what do you get?No, not the trigger for something really nasty when you pick it up...Right! You get a motion detecting switch.A bit like our gyroscopic sensors do now in our phones....And if you cut the tube lenghtwise you end with two opposing contact to switch two magnets on depending on what side of the tube is hit by the mass (contact) swining on the spring.Try it out with a spring from old pen and a screw inside as a weight - quite sensitive if you get the weight right.Some drawing suggest he height was about the same as the width of the machine.This would suggest the contact was actually hanging upside down, so it could swing in the wider base.A bit of fine and very flexible opper braid with a weight would make a nice pendulum here....Do a little experiment first though ;)Make a sturdy frame or if you have none try a truck. ;)If you place the frame on wheels and a pendulum with just a string and some sinker at the end - what would happen if you move th frame sideways instead of swinging the weight?Inertia keeps the weight in place while the top mount of the string moves away.And if the weight stays in place for just a fraction of a second before starting to move with the frame?Correct! since the angle of the string changes, the ball appeas to move up.Not really by much but enough for an electrical contact to open....We have some ideas now on how those electromagnets might have been triggered by Tesla, what about the mechanics of the moving mass that claimed to have created earthquake like results?Precision is no problem these days, just check these toy kits to build your own Stirling engine or you trusty old Swiss Army Knife.And even a second hand air cyclinder and piston can be modded to act like a free swinging air pump.Only question that really remains would be how to match the mechanical system with the electircal?We have two seemingly independent masses, one to make things move violently, the other to energise the part that make the first mass move - or to be precise to give it a tiny push in the right direction.What does mean you wonder...Let me try to simplify it down a bit.....If you push someone on a swing you can have a very hard time by working against the mass of the person sitting and enjoying the ride.Or you could give the person just a tiny push - right when the swing starts from the highest point to go back.Could that mean it is really as simple to build as Tesla claimed?If the top mass is limited by how far it can swing FREELY before the air pressure works against this movement then we would only have to set the length of the pendulum so the contact happens right at that point on the x-axis of the top mass.Ok, and how would that make anything swing at all?If the top mass is first energised there is nothing to stop or influence the movement, except the "air springs".So it totally overshoots like those metronomes on the board.It swings back and closes the contact on the other side of the movement way early as well.Now the electromagnetic impulse from the second movement actually works against the moving top mass.And this swinging of total non-control continues while whatever the thing is mounted to also starts to move, even if it is just fractional.Over time both swings, from the machine and the object, will get to point where they influence each other in a "positive" way.For Tesla's experiment one would say negative though as it was quite violent in the end.Little by little both swing will get closer to being in sync and with that in resonance.The electromagnetic push however continues....Only that now the top mass of the machine is in sync with the thing it is mounted to.The machine became you standing behind a big swing and trying push someone higher and higher....It is all just a theory though and any minor earthquakes that might register around my area are pure coincidence ;)

Topic by Downunder35m    |  last reply


Cloning the famous ARA-2000 antenna for SDR use

Several years ago the company behind the original ARA-2000 antenna, Dressler Hochfrequenztechnik, closed.The ARA series of antennas, like many other products by this company never got a patent, instead it was trusted that no one would bother to replicate it.A bit like the Swiss Army knife, many tried to copy it, none really managed to match the original quality.There is quite a bit of hacking still going on for this antenna, most projects though seem to be abandoned at the time of writing this.I am currently trying to figure out how to create an entire clone that everyone who knows how to properly use a soldering iron can build.There is a lot to consider here...The active element is of quite unusual shape and needs to be wound around a cylinder of a pretty accurate diameter.My initial tests showed that for example aluminium foil with some unavoidable wrinkles already has a negative effect.And a change in diameter of just 2mm means the entire antenna only performs badly for the entire band.This part is thankfully already solved to my satisfaction using thin copper sheets and some stiff plastic sheet.Quite a pain though is the MMIC part - the amplifier that makes the antenna active.There is a ton of MMIC blobs available, either solo or as a ready to go amplifier.Downside is that without really knowing any characteristics of the original is comes down to guesswork.And as most of the cheap SDR dongles won't provide a BIAS TEE I will opt for an external power supply for the amp.I might provide the option for a inline use a bit later though.Why clone the ARA-2000 antenna?For starters you need to forget the mythical stories you might have heard about this antenna."Picks up even the weakest signals!", "Totally linear over the entire bandwidth" and so on...Without the amplifier the antenna is actually not even average in therms of reception performance.My initial tests with a network analyser showed that the anteanna actually is behaving really weird (without the amp!).Although this first bit needs further testing, it seems that most, if not all of the work in the 1.5-2GHz range is done by just the straight connecting strup going from the amp, or in my test case the coax, to the wrapped antenna part.For anything in the more interesting frequency bands it seems that the antenna is not using anything like a discone, whip or ground plane antenna.Instead the 3rd harmonics of a given frequency provide the max power output from the antenna but it arrives at the cable at the right frequency.Especially in the lower frequencies, below 200MHz there is also quite some phase shifting happening.As a passive antenna it seems to be almost impossible to find a frequency to transmit on without using some matching trickery first.But when it comes to size or looks, the ARA outperforms everything you can think of unless you want to constantly adjust the length of your whip antenna.And if you check what is available in real (user) data in terms of noise and signal quality than most other antenna types are far worse.The design provides a wide frequency range with very little noise, almost like a build in filter.Considering that mostly harmonic frequencies are used not that surprising.Getting hooked on SDR means you start little and then you want more and more.Unless you really need the low frequency HAM bands below 50MHz the ARA is a good choice that just makes sense.What is quite surprising in the original is the total lack of protection for strong signals.Sure, we might never need a lightning arrestor because all is enclosed in plastic and has little attraction lightning, but someone hittiing the transmit button close by....I will have to do some more checks to determine whether or not more protection is required.What is the problem with amplifier?For starters, no one really knows what was used in the original - they all just guess based on how well the real design matches some datasheet.Means whatever was used might as well be a custom made solution.I checked a few datasheets for MMIC amps but could not find any useful reference to the handling of things like negative gain, phase shift or a constantly changing impedance.Some however state that a 50 or 75Ohm signal is provided at the output.If I interpret that correctly than those MMIC's not only amplify but also do some matching.In most cases you won't need an amp that works outside what the antenna can provide.Problem is that I don't like regretting things later on ;)So IMHO it would be best to use a wideband MMIC covering all from about 1MHz to a few GHz.Additional filters can then cut off what is not required or where the antenna starts to fail.What is clear by the original design is that the cable shield acts as a ground and most likely also has a balancing function.It would make sense to add a ferrite trap close the the receiver to filter out what the cable might otherwise mess up.Can the frequency range be lowered to get even the low HAM bands?The answer is YES and NO.It is not a big problem to extend the cone shape and then hope to come much lower.Issue with this is the helical, long periodic design.As basically only the 3rd harmonics are used for all interesting frequencies any ARA type antenna going much lower would end to be really long.You can't just make it longer!One thing is to have a full and even number of turns.The original only had two, three turns is bad, four means the entire antenna is slightly longer than your average downpipe for your roof gutters....Other, seemingly logical alternative would be to stick to two turns and to increase the diameter.Apart from the size problem here we would also change the shape of the foil quite a bit and I have not done enough tests with that to provide a conclusion.Are there alternative design options?As it turns out copper pipe is available in 80mm diameters for the use in chimneys as well as downpipes.With a proper machine it would be pretty straight forward to remove what is not used as the active element.Milling a pipe or rod is these days a common thing in many good workshops.But on a hobby level and low budget....One of the best options for cheap test antennas of this design is to use tinting foil - the cheapest you can find ;)Just read the lable and make sure it does not use a metalised film.If it has no UV protection and no tinit at all it is best but hard to find.A little less stiff is the stuff to cover school books or cupboards.Vinyl is bad though!If you look for copper foil in the cheap online places you mostly find the suff used for shielding in rolls of 200x1000mm.Unless you have a really sharp knife or really suitable sissors this stuff is a pain to cut as the glue tends to stick very good to whatever you use to cut through.Don't ever try one of these blade type cutters for paper and pictures unless you put a slight oil film on all cutting surfaces first....In some hobby shops you can get copper foil without any glue in different thicknesses - this stuff is the prefered option.Not only cheaper than the China rolls with glue but you invest a bit more and get a thickness that does not wrinkle right away when working with it ;)Cheap, steel downpipe and cutters or nibblers?I though about and I tried - and I failed LOLUnless you use a pin type nibbler and custom made rig the result is quite bad - at least mine was.What works though is to use thin aluminium sheets, cut them and then bend them around a suitable template.But I ran out of old laminated sings to salvage and the duble sided ones I have left are too much work.What comes next?Well, I have a few rolls of copper sheets coming next month, the cheap glue covered type.This time however I will leave the plastic cover on and use tape to secure the foil to the pipe.A two-stage amp with external power supply is coming too so I can do some more tests in this area.For the time being I will opt for some 3D printed end caps but with a bit of luck can find something easier next time I have time to waste in the hardware store.Excluding cable and a cheap USB or 12V power supply, the current costs of building the anteanna are around $40US.About half of that if you don't cennectors and attach the coax directly.Another experiement I am working on is to use copper tape, 12mm wide, to create the antenna in a semi-fractal style.I am hoping this will provide a high enough gain so the antenna is usable without an amplifier.Right now the biggest issue is to find a really SDR suitable way to deal with strong signal close by.I will keep you update here when I start with the new antenna and upload some pics along the was of building it.

Topic by Downunder35m    |  last reply


Go-kart upgrade: plastic "wheels" to real tires Answered

My son received a Kettler Go-Kart (2nd hand adventure) for Christmas, and it's a lot of fun, even for the mom who crams herself into it to give chase to the kids (make great tight turns). Goal: take it a bit more off-road than asphalt and smoothish ground. Currently: Plastic, rear wheel drive wheels (think Hot Wheel front wheel material we grew up with). Where I'm at, after perusing the internet for all things pedal go-karty: I feel like the front wheel assembly will be pretty easy to replicate. The nature of rear wheel drive, which stays straight (fixed) is the challenge. Images attached. What's the answer to the rear wheel drive assembly? How to replicate rear fixed driving wheel with wheels available at the big box store, or is there another question that needs to be answered first? is the chief concern prior to fully disassembling the go-cart. And/ OR, What are the magic words for finding the "wheel" answer? Thank you in advance!

Question by An1more    |  last reply


Does any body know were I can get red phosphorus. I need it for making matches.?

I realy want this stuff for some strike anywhere matches. I know that I can get it from safety match boxes but I don't want to spend the rest of my life collecting them. I will apreciate any help people can give me.

Question by nurdee1    |  last reply


List of Upcoming Contests (updated 12/16/19)

Hello everyone! Below is a partial list of the 2020 contest calendar. Keep in mind that this list is subject to change and contests will continue to be added throughout the year. The contests below are already in planning, and I've left off ones that we're still trying to decide on. The months indicate when the contests will be launching. All contests will launch near the beginning of each month. Keep in mind that the list below is not set in stone. All contests and dates are subject to change!JanuaryCoffee Speed ChallengeKids Solving Problems Contest Makey Makey Contest Wearables Contest Raspberry Pi Contest Fix It Contest Warm and Fuzzy Challenge Snow Challenge Magnets ChallengeFebruaryRope & String Speed ChallengeAfter School Challenge Meat Free Meals Challenge Crazy 4 Coding Challenge Fiber Arts Contest Heart Contest Paper Contest Trash to Treasure ContestMarchWire Speed ChallengeStorytelling ChallengePie ChallengePCB "badge" ChallengeSpring Cleaning ContestSoft Robots Contest3D Printed ContestClay ContestWoodworking ContestAprilRubber Band Speed ChallengeIndoor Plants ChallengeSpace ChallengeLeather ChallengeTea ChallengeCars and Motor Vehicles ContestArduino ContestFirst Time Authors Contest *All contests and dates are subject to change. Please leave suggestions for prizes here. You can also leave suggestions about contests here. Have a contest question? Check the Contest FAQ!

Topic by randofo    |  last reply


Does anyone know the easiest way to shake paint at home?

Have paint that hasn' been used for about 2 weeks and would like to know if there is any way to shake it enough at home that it will be mixed well to use.

Question by twoperki4u    |  last reply


How do i determine the number of coil winding/size in a axial flux generator ?

I am building a axial flux wind turbine, i have built a small one, now want to move onto a bigger one. but i couldn't find any information on how to calculate the size of coils for the required power output. example i want to make a 48v 5kw generator, how would i calculate how many turns is required, the wire thickness, how many coils per phase. can someone please explaining the process in determining all this?all the resorces online just give me numbers, example 72 turns of 1mm wire to get 48v, they dont tell me how to calculate it myself for different voltages or different power power output.any help would be appreciated thank you

Question by maaz1598    |  last reply


Prize suggestions and feedback needed! What would YOU like to win?

Hi everyone! Here at HQ we're always planning contests, but sometimes we run out of prize ideas. :D I would love to hear any and all suggestions for products you guys would like to win! I'd also love to hear feedback about prizes we've offered this year - what did you like? What didn't you like? Do you prefer getting a shiny new electronic toy or a prize pack more suited to the theme of the contest? Have a suggestion for a contest theme? Check out this topic!

Topic by randofo    |  last reply


Which is less in price and best

Insted of Raspberry pi we can use ardunio nano

Question by Sdvs    |  last reply


Beer cap gift ideas? Answered

I want to give my best friend a gift that somehow incorporates a metal beer bottle cap that has some sentimental value.  Does anyone have any ideas?  It can be anything (aesthetic or practical, I have no preference).  Thank you in advance!

Question by SirNoodlehe    |  last reply


How to Solve the Problem of Stepper motor only turning in one direction

I've finally had the time to start putting together the electronics package for a CNC machine, and already need to do some debugging. ;)I'm trying to get one stepper motor going with the v2.58 board, a RPi 3, Popolu DRV8825, and one of these stepper motors.I've used the Pololu FAQs to tell me how to hook up the stepper to the RPi CNC board. On my stepper motor A is black, C is green, B is red, and D is blue. I'm getting this from examining the documentation that came with the stepper motor, and I used an LED to verify which wires were connected to each other. I examined the traces on the underside of the board to tell me how things connected to the stepper driver through the screw terminals. The green connector should go to 2B, 1B, 1A, and 2A in that order if you're looking directly at them.I can get the stepper to turn in one direction, but not the other. It acts like it's trying to move by jerking around, but doesn't actually start turning. If I move it in the other direction there's some jerkiness at the beginning, but it'll start spinning, jerk a bit more near the end, and stop. I've put a short video of this on YouTube.I've tried using another stepper driver, and gotten the same results. I've tried various different wiring options, but all I've managed to do is change the direction of the issue. I've also tried moving everything over to the Y-axis, and gotten the same result. I'm convinced this is something to do with my stepper motor wiring, but I'm needing some help on figuring out the right way to do it.Any help?

Question by ganshangkou2    |  last reply


Slot car Lapcounter/timer

Good morning wise folks, Looking for ideas for a Slot car lap timer. I have a great set up using an old PC,but we are going portable and moving all that stuff is a pain. What would be cool is a stand alone for 3 lanes that could count laps,display lap time and remember fastest lap time. Oh and it needs to cost less than $20 per lane. Have some ideas?

Topic by 2FER SLOTS    |  last reply


Can you help diagnose my Seal-A-Meal?

I have a Seal-A-Meal brand vacuum sealer, that all of a sudden stopped working properly. It has no On-Off switch. You simply plug it in, and then put the bag up to the vacuum area and then press down and hold the lid when its vacuuming the air out and then seals the bag closed. When it stopped working, a vacuum bag was placed (as we normally would) and then the lid was put down and pressed. The motor is still running, but normally it makes a louder noise as its vacuuming the air out, and this time it didn't work. (No vacuum). Since it wouldn't vacuum the air, it then wouldn't also seal the bag. Oddly, when I remove the bag and close it (with nothing in there) it DOES make the high pitched-noise, the green light comes on (hands free) and then does the sealing, even though there is nothing to seal.  But when I put the bag in - nothing but the motor running consistently with no change in intonation of the motor and the green light doesn't come on and it doesn't seal. So with the bag - not working.  Without the bag, it seems to work. I"m using Food Saver brand bags but those have always worked in the past.  Any ideas on what to do to service it and hopefully get it working again?

Question by dgould944    |  last reply


Does the sailor uniform collar have any purpose?

OK. I know the reason for bell bottoms. I know the reason for the button flies with the button holes at odd angles. But I've never figured out the big square collar down the back.  Anybody know?

Question by mole1    |  last reply


Can you use a Plaster mold as a Blow mold?

I wanted to make a hollow plastic shape & not able to afford a metal blow mold. Can I use a plaster mold with wood reinforcement as a substitute for the metal one?The Idea is to heat up a plastic bottle that can fit in the mold cavity & slowly blow it up with an air compressor.You think this might work, or do you think I may need more reinforcement in the plaster?

Question by elkaddalek    |  last reply


Why Sub c batteries used in battery packs for drills?

Is this somehow related to discharge rate? I'm trying to replace existing sub c batteries, but their price is put me off. Can anyone provide some info? If use equal capacity aa, what the difference gonna be (once again discharge rate)? I would  really appreciate any info about this.

Topic by Extasy    |  last reply


Car wouldn’t start

I have Ford Focus 1.6 diesel. I left it for a week in airpark and when I came back trouble happened! Once I started the engine the battery light turned on then after driving for half hour ice light came on, soon after the airbag light and steering wheel light turned on too! After this the stereo turned of lost power and the light were getting shortened. The steering wheel got stiff and could only steer very little, I was in big trouble so I went on to low speed lane and had to drive for another 10 km in dark and in danger because whippers stopped working while was raining a little! I managed to bring the car home due to a luck of time and no cars because it was 2-3 am. Later on the car started but switched of in 2 min and doesn’t start after that! Can someone help what is going on with it please thanks.

Topic by Mir D    |  last reply


Speaker problem - surround sound not working

Hi guysI have a Panasonic SC-HT 990 system with four speakers (minus the centre and subwoofer).The subwoofer works perfectly, however, if i plug in the four floor speakers (2 front, 2 surround) only one will work.But, if I plug them into the same two speaker-wire ports in the main box, all four work. However, they wouldn't work as proper surround sound.Why is this? Why don't they work separated. I would imagine there is a problem with the connectors at the back of the main box, but can't see any issuesThanks

Topic by CraigHull    |  last reply