Potentially Lethal 'ibles

There are a lot of people recently  enquiring about "tazer" like projects, some with lethally inappropriate ideas which may well  lead to the death of either the builder or their target. Is the "inappropriate" flag an appropriate response  ? I don't really think we should be encouraging the creation of lethal weapon 'ibles, but hey, that's just my English sensibilities. What do fellow members from the country with the right to bear arms think ?  Steve

Topic by steveastrouk   |  last reply

What is the work done in shifting a charge of 2 Coulombs from pt A having potential +10V to pt B having a potential -5V? Answered

How will we calculate the potential difference? I'm not sure but I think the potential difference across AB is 5V.

Question by NishthaC1   |  last reply

Transformer vs Potential divider

Hi guys! I got bored and decided to make a study table light using LED's. My setup consists of 4 LED's in an arm and 10 such arms in parallel. I actually designed it in view that the transformer i used converts 230v - 15v. But after it all finished, i found out that all my transformers are used up for other circuits. I was wondering,  Can i use a potential divider for such simple circuits? I approximated that if i place a 46K and a 3K resistor in series and take the voltage across the 3k resistor, i will have about 15 v. What are the disadvantages of using such potential divider? 

Topic by charmquark   |  last reply

Potential $5 RC Hovercraft

Hey y'all, I was bored, so I made this RC hovercraft, kinda like a Tiny Whoov, from the guts of a $5 RC helicopter (sold at most FiveBelows). The idea is that a hovercraft is more fun than a cruddy helicopter, in addition to being a fun and easy DIY project for the weekend. It could be a nice gift to a kid. My first concern was that the motors would not provide enough power to get the thing moving. They give more than enough power, and this thing can MOVE. My second concern is that the differential thrust steering system (one motor turns faster than the other, steering the hovercraft) would not be effective enough. This is still a problem that I don't have the enthusiasm or time to solve anymore. Maybe someone could figure out how to reprogram the FC board to have more differential thrust (is that possible?), or somehow configure a servo or actuator without raising the cost of materials too much. Anyway, here's the concept, go have fun with it.Supplies:Foam platesHot glue$5 RC helicopter with 2 motors and receiver (LED optional, but really cool)Connector (the battery might be soldered directly to the FC board, so this will make it easier to fiddle with)Soldering iron (not %100 necessary, but it can come in handy)Propellers (see design notes)Design notes:Notice how the underside of the hull is curved and smooth. I used propellers from a Blade Inductrix FPV Pro, but any micro quad propellers should work. Notice the nice little compartment under the FC board where you can stick a battery without the need for Velcro or glue. This would be a very easy FPV mod, but that would add about $20 to the cost.

Topic by Thorondor95 

High Pressure bar - I see potential

Hmm, Browsing The electronics goldmine, I saw this: http://www.goldmine-elec-products.com/prodinfo.asp?number=G17814 Summarized: High pressure loaded hydropneumatic gas spring. This compression spring has an extended length of 32" with an inner rod diameter of 8mm and an outer cylinder diameter of 18.25mm. The compression force is 360 newtons (80.9 lbs of force) and a stroke of 366 newtons (82.2 lbs of force) The first person to post an idea for what this can be used for gets a patch! And maybe other people if I like the idea!

Topic by schumi23   |  last reply

Jobs for the Creative Techs?

I love studying electronics and doing creative things with electricity. I was an artist/musician throughout all of my youth and decided to switch over to creative electronics after discovering the art of circuit bending. I want to get a degree involving creative applications of electricity, but I'm having trouble getting a clear picture of what the job market is going to be like after i graduate. I am wondering what creative positions are available, not just with Instructables but in general. Are there any particular companies that would be good to look into? I'm trying to plan my degree so that it will be appealing to the companies i want to work for. I was an artist before i was a tech/engineer so I'm particularily interested in things such as product design, creative tech projects, animatronics, sculpture and art/music installations. Any advice would be great, I'm eager to find a job that will require my creativity and that isn't mundane. Is creativity something that is reserved to be expressed in my spare time or can it exist within the job market as well?

Topic by Vaginatron   |  last reply

does my instructable have potential? Answered


Question by Yerboogieman   |  last reply

Why not use a potential divider in power adaptor?

I thought I could put a bridge rectifier directly after the mains and then pass this through two high value and high(ish) wattage of resistor to act as a potential divider and bring it down to 5v. Why would this not be possible?

Question by versos-tk   |  last reply

Potentially revolutionary idea concerning remote power?

I learned in physics some time back that directing radio waves towards a metal object will induce an alternating current. My question is: Could you power something with an external but unconnected power source? I'm thinking something like a guitar with no lead that still manages to send back sound data to the amp. NB If this idea already exists, please tell me.

Question by The Jamalam   |  last reply

"Knex War?" (The Math Bit)

Hey guy! Sharir1701 here and I just want to start off by saying that I'm not back into Knex warfare, but I have something to show you. About a year and a half ago, I posted this forum topic. There I explained why, in my opinion, just adding more rubber bands to a gun will not actually produce an overall better gun (past a certain, low point). I'm not getting back into that discussion, but I simply wanted to share something regarding that. Don't ask me how or why (I don't know, myself), but a few days ago I suddenly remembered that old assumption I made. Being a perfectionist, I hate leaving things unfinished or unexplained (particularly math and physics related inquiries). Back when I posted that topic, I had little to no formal Physics knowledge, and the beginnings of an understanding in mathematics. Now, I have a much broader understanding, much more knowledge, and an ability to explain and evaluate what I once couldn't. Anyway, what I'm trying to say is, back then, I didn't have the tools to prove my claims. I firmly believed in them, but I couldn't confirm them. It's nothing complicated, but, like I said, just something I'd like to share. I also want to point out that, although I personally don't enjoy spending days upon days perfecting a little plastic mechanism for firing (mostly) non-aerodynamic plastic projectiles, anymore, there still is a warm spot in my heart for the craft I once loved. More to the point - this is a small article just showing something I did in a few minutes the other day, that helps me to better understand how a Knex gun works. I hope that in writing this, more people that are still building guns, will think about more accurately calculating certain things about their guns to help improve their performance and hopefully produce more efficient guns. The final note I have is that I'm about to show you equations, all of which can be plugged with real, measurable numbers, to calculate to a high degree of accuracy, the forces at play. This means you can actually calculate the most efficient layout for a gun, and also that in designing your next, you will be able to use these equations, and many others, to find optimal solutions to your problems. So, what's all this fuss about? Well, basically, I just proved with a few, painfully easy equations that my conjecture about the forces in a gun, working on the pin, is true. I'll just get to it: First, Hooke's Law states that the force necessary to change the length of a spring or a (tense) rubber band is F=K*dX, where F is the force, dX is the distance you want to change, and K is a constant number, that each rubber band (or spring) has. You can quite easily measure both of these. For rubber bands connected parallel to each other (assuming they are the same type of rubber band, which ever is your chosen standard), this equation becomes F=K*dX*N, where N is the number of rubber bands used. dX and K are both constant in the regards of the pull of a pin on a standard Knex pin gun. Therefor, the amount of force required to cock a pin (pull it back to it's full length) is linearly correlated to the number of bands you put on your gun. Next, if we examine Newton's equation of work and energy, W=dE=F*dX, where W is the work, dE is the change in energy in your system (input from an external force, i.e. your hand), F is the force applied along a length of movement, and dX is that length. Let us define the base position of the pin (not cocked, minimum tension on the rubber bands, fully in the barrel, etc.) as having 0 energy. This then means that the work applied to the pin by cocking it is equal to all the potential energy it has. From this, plugging in the force, we get Ep=K*(dX)^2*N. Let us assume a perfect world, where we neglect the effects of friction and air resistance, and assume all the momentum of the pin is transferred into the bullet as it fires (I will briefly mention in the end, why everything we're neglecting here just strengthens my claim in reality, but let's continue for now). After being released (in other words, shot), the maximum velocity the pin reaches right before the end of it's journey can be found using the equation for kinetic energy Ek=1/2*M*(Vmax)^2, using the fact that (again, neglecting energy wasted as heat due to friction) the energy is conserved, as no external force is working on the system, which then means that Ep,start=Ek,end => K*(dX)^2*N=1/2*M*(Vmax)^2 => Vmax = sqrt(2*K*(dX)^2/M) * sqrt(N). The first sqrt term in the final equation is all one big constant (again, K is the ratio associated with the rubber band, dX is the distance the pin travels, and M is the mass of the pin), meaning we can conclude that (C for constant) Vmax=C*sqrt(N). Finally, force applied by a moving, massive object can be calculated using Newton's second law, F=dP/dT (P is the pin's momentum, T is the time it takes for the pin to go from velocity Vmax to 0, transferring all it's energy into the gun and the bullet, but as I said, let us assume all of it goes into the bullet), or F=M*dV/dT (M, mass of the pin, dV is the difference in velocity, Vmax-0, which is simply Vmax. This is because P=M*V, which means dP=M*dV, ignoring relativity). So, F=M*C/dT*sqrt(N). The time varies slightly, but insignificantly, so let us assume it is a constant. So that's it. The force exerted by the pin on the bullet is some constant (calculatable, as mentioned and as shown), times the sqrt of N, the number of rubber bands on the gun. So there you go. Just a little something I did out of the blue the other day and thought I would share a proof of my conjecture from what feels like eons ago. I hope you enjoyed. Finally, I would like to tell you guys, perhaps as a little tease, since I'm not sure if I will ever upload it, but I have made 1 more gun after I stopped posting. I have already slightly teased about it in my user info. I guess I'll tell you guys what it is if I'm already posting something here again :) Possibly my most enjoyable, most well received, and quite innovative gun of all time? The REMPAR-2. I built the REMPAR-3 (I was also going to call it S5 when I thought about posting it). In a brief summary, it's a pump action, chambering (or bolt action as I and many others falsely used to call it), magazine fed rifle, that's only 5 layers thick all over, except one tiny area where it's 8 layers thick (1.5 extra on either side), as a reinforcement, not necessary if you use less rubber bands. Oh, actually, there's another small necessary area where it's 7 layers thick, but it's tiny and doesn't make the gun look bulky at all, and who cares. Plus, the one is around the pump, which looks quite natural, and the other is "disguised" as a detachable sight (not really detachable) that also looks fine. It also looked fairly good for a gun that I made, it used (if I remember correctly) a grand total of 0 broken pieces, which is a big accomplishment for me (the mag has some broken white rods, but fuck off), and it worked flawlessly, reaching ranges over 80ft and being able to go at 2-4 rounds per second, depending on your skill level with it. In other words, I could shoot 4rps; My girlfriend, with no experience or practice, could do 2rps, which says something about the gun's comfortability and ease of use in my opinion. It shot blue rods up to an accuracy of about 5x5cm (2x2in) over 30ft, which is amazing for a Knex gun, and it was truly super comfortable. It wasn't even long at all, which is saying a lot, looking at some other people's attempts at 5-wide pump actions (I may also be guilty of an attempt several years ago). Being quite short and only 5 wide, it is also quite light. I'm sorry, I just really liked this gun, I think it was truly my best creation ever (of course, the S3 is by far the most innovative gun I've made, but it's mostly a concept gun, not meant for real effectiveness). I may post it in the future, but I'll make no promises. I suppose I won't leave you guys completely hanging and take a picture of it. Oh yes, there's also a neat, fun little thing I did, originally because I saw no other option, but then I actually really loved it. I'm talking about the mag-lock. It locks automatically (there's a band on it, but it ripped a long time ago, so...) and the mag cannot fall out. Then you pull on it with your middle finger, similar to a trigger, and the mag just drops right out. Love it :)

Topic by Sharir1701   |  last reply

Potential Instructable - Automatic Security Cam for your Macbook

I saw this on the Make blog and thought it would make a good Instructable. Anyone up for the challenge? It seems like most of the information is there in the comments:http://www.makezine.com/blog/archive/2007/01/automatic_secur.html?CMP=OTC-0D6B48984890"This came out a few months ago, but I just found this on Flickr while researching the upcoming weekend project. It's a way of automating your isight to take a picture 60 seconds after you, or anyone, open it up. Flickr member omegastation set this up before sending off his macbook for fixing. In a worst case scenario, if someone stole your macbook, you could have your macbook send you pictures of them.I set this up and I made this little automator program that takes and sends the pictures, but I don't have a lot of experience programming from a terminal and I got hung up on step 5. If someone could make a little screencast of how to set this up, that would be awesome. This seems like it would be a simple first programming project!Update: Check the comments for super explicit instructions... with these instructions, anyone can program this now! Thanks Omegastation! "

Topic by ewilhelm   |  last reply

Is it okay for family members to enter and potentially win the same contests?

Hello and thank you for taking the time to look at and potentially answer my question.     Since I I started writing Instructables some months ago, my mom and little sister have both started writing as well.  It has been great fun writing along side them as whenever we meet up to have a family dinner the converstation usually turns to contests or ideas for new Instructables that we think would be really poplular.  Up until this point we have all been entering different contests following our natrural affinities for certain types of projects but now a few contests have come up that we'd all like to enter.  So I was just curious if there is a rule against family members enter and potentially winning the same contests.  Thanks for your time!

Topic by Matt Makes   |  last reply

match potential emergency energy sources w/ critical equipment

Trying to match potential emergency energy sources (solar, inverters, auto/marine batteries, wind turbines) with particular devices necessary for emergency response planning (laptops, flashlights, refrigerators, handheld radio units, other RF gear, wireless/wired networks) 1. Trying to calculate how much energy and in what form we'd need to, for instance, reliably keep a laptop running during power failure. 2. With respect to devices that need DC power - such as walkie-talkies - which are usually recharged (at least in North America) from AC power, through a DC converter, and then charged:: is it possible with devices which generate DC power - such as solar PV generators - to charge them directly without converting to AC and back to DC? We're looking not so much for particular matches between power source X and device Y - more methods for making the calculations.

Question by jsoroko   |  last reply

Converting gravitational potential energy into air pressure to launch a projectile?

Hello my name is Aaron! I am a high school senior from northeastern Kentucky designing a pneumatic system of sorts for a science competition and need some help. I will be building a device that converts gravitational potential energy, from a falling mass, into air pressure (or possibly the movement of air depending on the design) to launch a projectile a specific distance (max distance needed is 8.25 m). What I am thinking about doing is using one double action pneumatic cylinder (DAPC) as a bellow in which a falling mass (max 3.500 kg at a max 90 cm) would strike its piston shaft, creating positive pressure within the system. With that positive pressure another DAPC’s piston would simultaneously strike our projectile sending it airborne in theory. Below there is an illustration of my idea, sorry about the poor quality. So what I need help determining is would this design work before I start buying parts? If so what approximate sizes should the two cylinders be and should they be different sizes to maximize the force exerted on the projectile? If you have any other ideas concerning the design or any questions about the project PLEASE feel free to share!!! Below are some of the design rules that pertain to this project along with some notes in italics about them. Thank you very much for your time in advance! ------------------------------------------------------------------------------------------------------------ Description:    -Prior to competition, teams will design, construct, and calibrate a single device capable of launching projectiles into a target and collect data regarding device parameters and performance. Design Constraints:    -The launching force must be entirely supplied by the gravitational potential energy from a falling mass less than or equal to 3.500 kg. Any device part whose potential energy decreases and provides launch energy is considered part of the mass. The mass may consist of multiple discrete parts, which together count as the total mass.    -During each launch, the gravitational potential energy must be converted to air pressure or air movement, which is then used to launch the projectile, either directly (e.g., pop gun style, etc.) or indirectly (e.g., using a pneumatic cylinder to swing an arm, etc.) All device air chambers must start at ambient air pressure and must automatically return to ambient air pressure.    -The launching device (would look similar to this with the adjustable angle to accommodate different ranges), including the projectile and all components, must fit within a 75.0 cm x 75.0 cm x 1.00 m box in ready-to-launch configuration, in any orientation chosen by the team. Weights used to stabilize the device must be within the box.    -The triggering device (would look something like this except elevated with a mass suspended ready to be released) in not considered part of the device and must not contribute energy to the launch. It must extend out of the launch area, allow for the competitors to remain at least 1.00 m away from the launch area, and does not need to return to the launch area after launch. The triggering device must not pose a danger to anyone due to flying parts or excessive movement outside the launch area.    -Teams must provide unmodified tennis, racquet, ping pong, and/or plastic practice golf balls to be used as projectiles. Teams may change projectiles for each launch.    -The launching device must be designed and operated in such a way to not damage or alter the floor.    -Electrical components are not allowed as part of the device or triggering device. The Competition:    -Two targets, designated by small marks on tape on the floor or panels lying on the floor, must be placed in front of and centered on an imaginary line parallel to the launch direction that bisects the launch are. Supervisors are encouraged to place sand, cat litter, or similar substance in the area around the targets to help indicate landing spots.    -The targets must be placed in front of the launch area at distances between 2.00 m and 8.00 m (in intervals of 10 cm). A distance of at least 2.00 m must separate the targets. Target distances must not be announced until after impound is over and must be the same for all teams. Room ceiling height should be considered when setting the distances.

Question by ahoback   |  last reply

A new (and potentially real) way to produce hydrogen from water

A report in Science News today describes the results of an extremely detailed molecular simulation (full non-relativistic quantum mechanics) which shows how small clusters of (less than two dozen!) aluminum atoms can catalyze the dissociation of water into hydrogen with very high efficiency.  The paper has apparently been accepted by Physical Review Letters, but there's nothing up on arXiv :-( Before the alternative-energy fringe starts jumping up and down, the big roadblock to this mechanism is how to fabricate and distribute aluminum atomic clusters (called "superatoms" in the report; sigh...).  Making "nanoscale" (another annoying word...) clusters of atoms usually involves high temperatures and vacuum systems.   Together, those will consume substantially more energy than you recover from making and burning the hydrogen. However, if that roadblock can be overcome, then this does become a viable technology for fuel cells:  fill a tank with water, pour in a pouch (or bucket) of aluminum clusters (magic pixie dust :-), and hydrogen starts bubbling out.  It will be interesting to see how this shakes out Oh, and the simulation makes cool pictures, too!

Topic by kelseymh   |  last reply

Computer Cable problem. Could I potentially screw up the sync? Answered

Hello, I recently was reorganizing my desk and I decided to use these tubes to organize the cables and such.  I was just wiring up the speakers when I noticed I was using too much tubing so I cut off the excess. In the process of cutting I accidentally cut the cable to my left speaker. The left speaker is completely independent from the right and only connects to the sub-woofer.  My question is, if I were to repair is and I lose some length in the cable, will that disrupt the sync in audio? In other words, because the left cable is shorter, the electricity will travel faster and produce sound from the left before the right (theoretically).  I am also producing music so I kinda need to make sure that the speakers are in sync. Do you think that if some loss in length will affect the audio?

Question by Iridium7   |  last reply

Battery provides a constant potential difference all along its life time? Answered

Will a 12 Volt battery provide the same potential difference of 12 Volt even after using it for long time? Or it will decrease from 12 v to 11.5 and then 11.1v  and then to 10 v ...................5v.............3v.................0.5v,0.1v and then at last 0v with usage? Give reason if it works as constant source of potential difference supplying agent.

Question by deepakmurali   |  last reply

TDAC 2.0 concept video demonstration

Hey guys ! this is a video demonstration of my new idea for the TDAC concept, which i made about 2-3 months ago for TD, when i was gonna work on it with him (we never did, but oh well). i'm uploading this now so that anyone could give the concept a try as well. if you don't fully understand the concept, you can go check out TD's original concept on one of his forum topics. i encourage anyone at all, veteran or new, to try this concept, for it is simple, but challenging and tricky. also, it might be a round for the KIC sometime, so...

Topic by Sharir1701   |  last reply

grounding + 24vdc ?

Can someone explain the following, I got 24 VDC power supply (or take 1.5V AA battery) which is connected to 110VAC outlet on the input, potential difference out of the power supply is 24VDC node (+) to node (-) and potential difference of either one to ground is 0V (outlet ground). Now I take wire and ground (+) of the 24 VDC to outlet ground. Questions: 1. Why i am still measuring 24 VDC across (+) and (-) nodes ? If ground (call it whatever common) is 0 v and ground is touching (+) which was prior to shorting it to ground raised in potential by 24 V in relation to (-) that means (-) is zero potential? Or is it + 24VDC and - 24VDC but than potential difference is 48V at the output of the power supply. 2. Does that mean that I raised the potential of the ground to 24V? Probably not Thanks

Question by onaumov   |  last reply

How do you know if a capacitor is finished charging to its full potential capacidence?

How do you know if a capacitor is finished charging to its full potential? Also if you were to have a group of capacitors linked together in a series or parallel fashion how could you determine whether or not the capacitors were charged completely? I am mainly referring to polarized capacitors. 

Question by Dr. Kreap   |  last reply

Which diagram would work best(want leds to work at their max potential, Help? Answered

Specs on all 3 leds  1 watt, red green blue Maximum forward voltage: 4 Vdc Maximum forward current: 350/ 700 mA (if you pick a diagram with a resistor please let me know what rating Ty)

Question by dougiedougworld   |  last reply

How can I design and develop a earth resistivity meter for groundwater exploration upto a 200mtrs investigation depth

This meter will contain 2 set of meter, one to measure current injected into the ground and the other one to measure potential or voltage between 2electrode potential.

Question by gtscrustal   |  last reply

Two or three of my six grand kids have the potential to be DefCon Kids now what ?

So I have access to six young minds by helping my wife and retired teacher to sit with them 4 days a week. Four I drive to school while the parents (my children) earn a living.  Two are easily motivated and do well with Legos.  One likes robots, they all do math window games. I teach chess and play when thy want ( no Queen or rooks for me ) Programming is my artistic expression but I would push too hard and blow them away. What low level intros can be a leap into DefCon Kid status that you know worked well in your experiences ?

Topic by iceng   |  last reply

How can I eliminate the electric potential difference between my power supply's negative and ground?

Hello everyone! The question is pretty straight forward, I have my fair share with electronics, so I'm not really new. I have a linear power supply in my shop and only now it has started bothering me that there is like 35V between my psu's negative and ground. I would normally not care, but since I've gotten into audio and video I found it to be problematic, because every time I connect my psu's negative to my lets say source audios' negative, 4 amps start to flow from my amp to ground trough the thin audio cable I use. I know it's not my source's fault because it's switching psu's negative is shorted to ground.

Question by R4MP4G3RXD   |  last reply

custom cellphone battery charger drains out the cellphone battery..why?? Answered

I made a cellphone battery charger from 3 AA batteries.The combination of 3 AA batteries was at a higher potential than the cellphone battery, but when i connected both of them for charging, the potential of 3 AA batteries remained same but the cellphone battery was completely drained.why??If someone could explain maybe??

Question by chatsbk007   |  last reply


I am looking for a feasible DIY method of depositing aluminum from solution or vapor through electrostatic or other means. I've found one possible process using an ethereal solution of Aluminum Trichloride and Lithium Hydride. Will this allow an aluminum electrode to ionize into solution without adding more and more AlCl3? Is there a better way, such as potentially vapor deposition? Has anyone had experience at this? What are potential problems and how would you circumvent them?

Topic by bowakowa   |  last reply

What type of rubber will glue to acrylic and not smell bad?

I would like to glue rubber to acrylic (and leather/cloth potentially). Neoprene worked perfectly, but the smell is horrible. Is there another type of rubber that will easily glue to acrylic and not smell? Silicone maybe? Natural rubber? I have read that both of these also potentially smell, but clearly someone has figured out how to use these without the odor. (...and do you happen to know where to find sheets of this material?)

Question by ScottR226   |  last reply

Voltage: In search of a better analogy than water

I need to come up with a good analogy to describe the concept of Voltage. Water seems to be the most common analogy, but it seems to fail in some way. Here is a good water analogy that I found, but it still leaves questions that I cannot answer.The Lake Analogy: No force is pushing or pulling on the water inside a lake, so nothing moves. If it were possible to lift up on one side of the lake and tip it at an angle, gravity would pull on the water and it would flow. We have created a gravitational potential difference. The side that we lifted up on now has a higher potential than the lower side. Gravity will always cause water to flow from the point of highest potential to the point of lowest potential. The higher the difference between these two potentials, the more electrons will flow; the greater the current will be.Electricity is the same. When we attach a battery to a copper wire, the battery’s internal chemical reaction has created an electrical difference in potential. The negative terminal of a AA battery, has a higher potential than the positive terminal, so electrons will flow through the wire from the negative terminal to the positive. In this case, each coulomb of electrons will have the potential to do 1.5 joules of work as it passes through the wire. QUESTIONS: Does Voltage Push or Pull Electrons? The negative terminal of a AA battery repels electrons. This pushing force is what moves the electrons. However, we also know that electrons are attracted to a positive charge. So, are the electron being "pulled" by the positively charged battery terminal while being simultaneously pushed away by the negative terminal... or... does the negative terminal push the electrons away to a certain point, when the positive terminal begins to pull on them?With water, the only force is gravity, which is a pulling force. But with flowing electrons, it seems like the water analogy would require a pump there is only a pull, and no push. I guess... if you use a water pipe instead of a lake, and you use a water pump as an analogy for the battery, the end where the water is pushed out of the pump would be the negative terminal, and on the other end, water is being sucked into the pump, so that would be the positive terminal. But could you say that the sucking action of the pump is pulling the water towards that end, or the pushing action of the negative end is pushing the water towards the positive end? or Both? If so to what degree, and when? Meaning... as a water molecule is pushed out of the pump, is the sucking end already acting on and affecting the molecule, or does the sucking action only exert force on the water molecule at a certain point? It's all a real brain bender to me. Does anyone else know of a rock solid voltage analogy, or how I can improve this one?

Question by Dolmetscher007 

WheatStone bridge

Recently i studied the wheatstone bridge in me physics book in class but i could not understand it properly. I asked the teacher about my confusion but he also dont know. i have posted the picture of topic(wheatstone bridge). My question is ;1.Why current I1 is following through point A to D in loop ADBA. 2.Why current I2 is following through point D to C in loop DCBD.My confusion is that why current are following through these two paths. As current always flow through level of a higher potential to a level of lower potential but here it seems opposite.

Topic by DabuHackker   |  last reply

Shotfun Updated: Ammunition Modification

I've just posted an update to my Double Barrel Shotfun Instructable - an ammunition modification! Go see the all-new Step 9. It's potentially very messy...

Topic by Kiteman   |  last reply

Will the PS3 come out on top in a couple years?

The X-Box 360 is evidently doing better now, but will the technical potential for the PS3 make it come out the better console in a few years? Explain?

Topic by Toddson   |  last reply

I'm curious how a person could make a headband out of wood. How would you get that kind of curvature out of wood?

I was wondering if one could potentially make wooden headphones.

Question by plasticpopcorn4   |  last reply

Open Source Farm Robotics

Not sure where to post this, but it's something that will be of interest to others and use one often comes here for ideas and to get help for this guys project as it has massive potential as its Open Source Tech. http://go.farmbot.it if anyone has any ideas or wants to see about forking some stuff back and forth suspect that the Designer will be happy to chat. One was thinking that he hydroponic groups, lighting groups, ardeno enthusiasts, raspberry geeks, hardware hackers etc. However, its getting word out and getting the right people to hear about it... It has potential one feels to help change how we approach Open Source.

Topic by mattadlard   |  last reply

hexagonal box design?

Looking for tips for efficient design of wooden hexagonal boxes, bottoms, and lids.  Jewelry boxes, canisters, etc.  How to clamp for glue or air brads - I'm thinking a hexagonal jig, but that's potentially a lot of jigs for different-size boxes.

Question by rjvoyerjr   |  last reply

i need to know how long it takes to make a bespoke bag, be it a uni, school, handbag or or laptop bag.

The bag could potentially be made of any material, i just need to know the process, and most importantly the time it takes to make it on average.

Question by wasim2139   |  last reply

Best/Worst Magazines

Please forgive me if this topic has already been discussed in the forums. With the holidays up and coming, it seemed like a potentially good time to look into getting some magazines for monthly reading material. That said, what are your favorite (and least favorite) magazines? --Purduecer

Topic by purduecer   |  last reply

Motors, time and boredom

I have been collecting motors for a while now, and have no idea what to do with them. They range from 5-12VDC, brushed, brushless, stepper, etc. Any potential ideas for projects would be appreciated.  Thanks!

Topic by dansassin   |  last reply

Would it make sense to draw power at night from the grid, and store it in batteries for use during the day?

I was flipping through Make:18 that was talking about energy use. I realized that some people include a large battery array in connection with their solar setup to provide power for their EVs, or potentially their house... So stepping away from that, could you take a large battery array, and have it store up power during the night, to use during the day? This would offset grid consumption during the daytime hours (when it's higher), and potentially lower energy costs (as drawing power at night is sometimes cheaper... although that would probably be negated by the battery array)

Question by aarone   |  last reply

Mr Super Glue dies.

Harry Coover, accidental discoverer of Super Glue, has died in Tennessee, aged 94. Coover realised the adhesive potential of cyanoacrylate in 1951, when an assistant noticed that a piece of the material had firmly stuck two optical prisms together.

Topic by Kiteman   |  last reply

Frogs Forever?

Here's a neat video of bullfrogs clumsily catching prey in gorgeous slow-mo from the Vancouver Aquarium. They point out that amphibians are potentially facing a mass extinction, due to wetland reduction and chemical contamination. (Check out the crazy gender-bending effects of herbicides!)

Topic by canida   |  last reply

whats this job called?

Someone who works alot with energy (kinetic potential, chemical, mechanical, electrical etc;) and technology called. also is their somethins with those two and construction building. so its consturction, energy and technology. also what are soe jobs just working with energy or technology.

Question by DELETED_JAZ97   |  last reply

Help with the LM1875 amplifier chip?? Answered

 do i need a 4A supply, or is that just the most it can handle? ie can i use a 18V 1.4A transformer with it? i realize it wont be working the chip's potential, but that's not a big deal to me i just want it to work.

Question by tigerdog330   |  last reply

Has anyone made a home spray dryer to make particles?

Has onyone tried to make a spray dryer (see below)?  I am interested in making microparticles and this is potentially a method, but they run about $30K . http://www.buchi.com/Mini_Spray_Dryer_B-290.179.0.html Thanks.

Topic by bmvogel95   |  last reply

Why you can never have a "true" knex semi auto with decent power/range.

Ok here goes I will try to simplify my theory down a bit so everyone can understand: basicly energy cannot be created or destroyed, it can only be converted, eg kinetic into heat, chemical into kinetic ect. Knex guns are no exception, the enery has to come from somewhere, in most guns this takes the form of pulling back a pin or rubberbands to create potential energy, this is released when the trigger is pulled, this potential energy is converted into kinetc energy and this is how the bullet is fired. A semi automatic gun is required to fire every time the trigger is pulled, but the energy still has to come from somewhere. RBG's take this into account as each band is pulled back and has potential energy stored, however many knexer's opinions differ on whether this is truly semi automatic, many calling this type of gun a psuedo semi auto. Other guns use the energy imparted on pulling the trigger to create the potential energy to power the bullet, this is considered to be a true semi auto, however the main drawback of this system is that the amount of energy that can be transfered from the trigger to the bullet is very limited, therefore this type of mechinism has limited power. So if the problem is energy how do we solve this? one possible answer is to have an extra source of energy, such as a motor or a winding system that puts extra energy back into the system, however this approach will not give you a "true" semi auto as you will have to have an external source of energy, that and the fact that knex motors do not have the power and torque needed for this system. So what's your opinion, do you have anything to add?

Topic by Fred the Penguin   |  last reply

Graphic Design

I'm from Bangladesh, we are online base photo editing company, we provide all type of image editing services such as clipping path, photo retouching, color correction and related services. Can anybody to say me how can I got my potential client? Thanks in advance!

Topic by rustam203   |  last reply

New referrers data

In the latest release of Instructables, we added information about who is linking to an Instructable. You can see it in the info box under the stats tab. What do you think? Is this useful? As a potential author, would seeing that an Instructable gets traffic from many search engines encourage you to post your project?

Topic by ewilhelm   |  last reply

Revision3 looking for inventors in the SF Bay Area

Hey everyone -  We here at Revision3 are looking for a couple smart inventors located in the SF Bay Area for a potential online series. If you're interested in participating, send a video of you and your invention (or inventions) to inventors@revision3.com Thanks a lot! Revision3.com

Topic by Invention3 

Tesla turbines as viable generators?

Anyone have any thoughts about Tesla turbines, potentially as something steam based to plug into an alternator? The internet seems to be of the opinion that they're either fantastic or crap. I'm thinking of this as an easier and cheaper option than a steam piston or Stirling system for my solar energy thing.

Topic by SolarFlower_org   |  last reply

Is polycaprolactone food safe? Answered

Polycaprolactone ( aka "Friendly Plastic" aka "Instamorph" ) is a very interesting material with lots of diy potential.  I wonder, since Wikipedia mentions it is used in surgical implants, does that mean also that it is food safe? And If it is food safe, is it also aquarium safe? Thanks for any insights

Question by foobear   |  last reply

Motor Control System for large Robot? Answered

The motor System So I am working on  building a robot using wheelchair motors. I'm trying to control it via an arduino potentially but I'm not sure how to do this. My plan is to potentially use an 8channel 10 amp relay board connected to the arduino, but I'm not sure if 10 amps would be enough for the wheelchair motors? Also how do I go about actually powering the motors (12v Lead Acid Battery?) and interfacing that with the arduino (can I?). My other problem is that I would like to have at least a couple servos on each of two arms of the bot....so could I potentially control all that with the same arduino or would I need either a second arduino or an arduino mega with motor shield to do that?  The navigation My other problem is navigating/control..... For that I'm thinking of using an ultrasonic ping sensor or two if that's possible, again I don't know if I can fit all these things on an arduino or not. and Lastly to actually control it, I know I should be able to program it autonomously with the arduino but what do you think is the best way if I wanted to be able to manually control the bot as well?  Thank you so much for any guidance you guys can give on this large project!

Question by dstech   |  last reply