The forums are retiring and are now closed for new topics and comments. The existing content will remain online and accessible through 2020 to provide everyone the opportunity to save any relevant information. In the spring of 2021, these Community forums will be taken offline.


Shotgun *stalled*

This is my airsoft shotgun. It is quite near completion, however, i'm stuck. I have two m120(?) springs powering this beast. I need to come up with a trigger system that will hold back all of this force, while still having a semi-easy trigger pull. There is a metal screw that needs to be held back once i pump the, well, pump (the screw is pushed back by the pump.) Any input on this would be greatly appreciated. (BTW, i thought about a paint ball gun's trigger, but the only problem with that is that the screw has to lock back too far for this to be a viable option.) Also, the third picture is a shell. It would be filled with approx. 30 bbs and a cotton ball or toilet paper would plug both ends. The bolt has a part that extends through the shell and would force the bbs out.

Topic by Dr meat201    |  last reply

Can a silver necklace be used like Colloidal Silver ? Answered

Collodial Silver (silver ions in suspension - usually water) is supposed to have antiseptic properties. Do you think it would be enough to simply place a piece of solid silver jewellery into water to get more or less the same effect - even if the item was left in solution for, say, a week or so? Thanks.

Question by kevinhannan    |  last reply

V-Gate Motor, what is fake, what is real, why is it not possible

If we look at so called magnet motors than they usually share the common works of a V-Gate somewhere.So with the energy crisis blooming it might make sense to take a look on how these fance toys are supposed to work, or not work.You can check Wikipedia and watch a lot of Youtube videos showing magnet motors or just V-Gate magnet toys in operation.As the name suggests the permanent magnets are placed in a V shape configuration.Either linear or in a circle / on a drum.And the working theory suggests that if you place one or two magnets at the right spot in relation to the V than forces will make things move.It is great fun to play with a V-Gate just to figure out how the magnets actually interact.The longer you play with it and experiment the closer you think you are to actually make it work.No matter what you try though there is always a spot or an area where the magnet do the exact opposit of what they are supposed to do, the bind instead of making things move.Especially in the videos you can see a lot of interesting ways trying to compensate for this or to fool you.And the thing really no one wants you to know is that the pushing forces you want actually reverse half way through the cycle.But at this point their forces are already quite low.Would make sense now to just use that part of the V that actually works and to repeat it, doesn't it?If you do then you always end up with the same as what you had before, just more sections of it ;)And since in nature everything is equal we can not make the unwanted forces disappear and only keep the ones we want.Or can we? ;)A flywheel is a good option to preserve energy and to store it.No wonder then that people like to go big and include as many magnets on the drum as possible, preferably big and heavy as well...And since we can see in some videos that you can even make it spin by moving the magnet bar by hand: How hard can it be to do it properly?A flywheel needs energy to get going, especially if heavy...If the system would have the energy to make this spin then for obvious reasons it would only get faster and faster - but none of these toys do this...And well, moving your hand requires energy too ;)But combined with a mechanical or magnetic link it shall work just fine, timing is everything...And so you keep going and trying and in reality get nowhere at all.As said, you can't have only positive forces without the corresponding negative force(s).Modern approaches to the problem....The famous Yildiz generator uses all sorts of tricks.For example electromagnets to cancel out the field of permanent magnets, powered by internal generator coils of course.Or shielding around some magnets to direct the magnetic field in other directions.Others try to use a different angle for the magnets so seemingly one side of the field is stronger than the other.And the real enthusiast even machine their own magnet shapes from block magnets to get the field lines where they want them to be.In some case you can even find claims of commercial products in operation, with a convient link to order you own on a long term contract.This seems to suggest that there is indeed a way to create at least electricity for "free"....Of course this only made more plausible by the "security packets" included with these lease agreements.Sealed units, 24/7 remote camera surveillance, online connection for remote monitoring and on the go adjustments....And, no without the constant feedback from base operations through the online connection the "generators" will just stop.In a way all this only makes the search for the holy grail of magnetism more interesting.Just consider this:If it is worth to waste god knows how much money to create elaborate fakes with supporting websites and articles seeded all over the net, then why is it worth it?A real money scam would be exposed quite quickly and the websited disappear with the business.And if it is a real and registered business then they have to make the money somehow in legal ways.A balanced approach to the realities and options to make V-gate motor/generator as a workable toy....We know we can cheat and we know we can use modern materials.To make an interesting toy we would need to make it look and work interesting.Just a moving drum is boring and prone to be called a fake right away.Some fancy lever moving the magnet bar is nice but already well too abused to pass.Gearboxes and cranks however are not used that often due to the complexity of creating them in your garage.And some mechancial master creation displayed in museums of other places as "perpetual" motion machines are insanely complex.It comes down to first mapping the areas of negative impact, then finding ways to compensate for them.Preferably in some fancy optical way.Like the magician uses slide of hand to fool you you distract the audience by providing them things to focus on.The more focus on the workings behind it all the more they forget to understand physics ;)For example: If you want to lift the magnet bar you can use a fancy looking crank wheel that is overbalanced for the binding forced of the magnets - fools the unsuspecting person to think you actually eliminated the forces while in reality the wrong balance causes a problem later in the spin.And for those who were able to fllow that trail correctly you have something like and additional magnet moving to compensate fr this wrong balance.....Just make sure you seemingly complete the circle of force elimination back to where it started ;)Mumetal...Not, it does not come a cow....And yes, it is a real thing and not a fancy make up free energy freaks created ;)Unlike normal steel or iron Mumetal is extremely good in directing magnetic fields.For example the positioning head of your hard drive uses a pair of magnets on Mumetal plates to make sure the close proximity won't affect the disks storing your data.Now, some people on the net use these features to really fool you badly when it comes to magnets.From magnets in loudspeakers they misuse the term "shielded" to state Mumetal actuall shield the field of a permanent magnet.True is only that Mumetal provides pathway for the magnetic field that is thausands of times easier to follow than air.For example:A strong manget that still creates a noticable field at let's say 3cm distance.A Mumetal of 4cm in diameter placed 1cm apart would make the affects of the magnetic field disappear at 3cm.But not because the field is shielded, because the magnetic field lines now have an easy way to follow.They just "can't be bothered" anymore to go around the plate.In terms of utilising these effects for a V-Gate toy we can get really creative indeed.Some classic V-Gates use a magnet facing north on one side and a magnet facing south on the other side of the magnet bar and drum (left,right).Proving a Mumetal strip between them increases the field strenght on the other side quite a bit.It also allows for a much smaller extension of the field to the sides.And whatever area is covered by Mumetal will not show such a strong field, or none at all.So it would make sense to create a fancy gearbox to rotate a magnet bar.With every set of magnets on the drum the magnet bar makes one rotation.Like a real DV motor so to say.While the magnets attract each other the "active" side is exposed, and when the point comes where they would start to bind the "shielded" side is exposed to the drum.And like with all good mechnical toys we would have to find a way to revers the rotationthree times during one rotation of the drum to "compensate" for the reverse changes with a magnet bar that has a fixed spacing.Pushing instead of lifting....If two mangnets are used for the magnet bar it becomes obvious that a lot of "force" goes sideways instead of being used to actually push the drum.Hence the V shape to fool you the shape actually makes pushing possible to start with.Now read carefully and try to follow so you are not getting fooled by the explanation how to fool other people:For get an even base of understanding I will start where the closed end and the open end of the V meet on the drum, right where the pushing action starts.If the distance of the bar magnets dicreses with the V shape than we get even pushing forces working for us without the problem of reversal half way through the rotation.However we do get insane binding forces right when we get back to the start point of our rotation.Here we flip the magnet bar one full turn while the drum moves from pushing to pulling/binding.The direction of this rotation is important as it needs to match what the drum does.At the point of half rotation of the bar the single magnets move outwards again to be back in the start position once the rotation is complete.Complex mechanics, I know...The good thing is that you can always claim you get the energy for the action from the flipping of the magnets and that of course is not done by the mechanis, the magnet bar is flipped by the interaction of the magnets on the drum when the cycle repeats and drives the mechanics due the the inertia of the drum ;)So, is it possible to make it work without cheating and fooling?Sure it is.All you need to do is close the loop and make sure there is always more energy going into moving the drum than stopping it ;)Of course things would be much easier if you would find a material that actually blocks a magnetic field similar to what an opposing field would do but without the involved repelling forces.Like sunglasses for magnetic fields so to say.

Topic by Downunder35m  

DIY Card Game Playmat?

I have recently started playing Magic: The Gathering, and was looking to get a Playmat, I would like to make one because I don't want to spend a ton on a mat, I was wondering if anyone had any links to a tutorial on how to make a portable one from scratch for under $5? In case you don't know what they are, here is a link to some (;=5090 ) Thanks.

Question by Tuckoguy    |  last reply

Password protected door lock from Windows PC

Hello mates,I am looking for some leads to design and write code for a door lock which can be controlled from a PC running Windows, when the right password (which can be programmed) is entered.So, basically, the PC screen will display a key pad. When you enter the correct password and hit "Enter", a solenoid connected through USB port or connected through Bluetooth or WiFi shall operate. The password shall be programmable.If any of you have links, leads, expertise in making something like this, kindly share..Thanks a lot in advance..

Question by girishrajg  

Easy/Cheap Heating Element?

Is there any way I could make a DIY heating element? Or, if not, is there anywhere I get get one on the cheap?

Question by LiquidLightning    |  last reply

Led room lights

Hey everyone, so I bought two packs of a 5 meter led light for my room. When I tried them individually everything was working perfectly, and because they are multicolored I tried all the lights and it was fine. After that, I connected both pakcs together and when trying to click the white light in the controller for them to work they started to beep all over again, the weird thing is that the rest of the colors work well, except for the white. What could it be, and how could I fix it? Please help me, I'm trying to install it for my daughter for a surprise and I don't want it to be ruined just my that. Thanks

Question by lrestreposalinas    |  last reply

Has anyone ever made a room furnace with a light bulb? I've heard of using light bulbs contained in a metal box. Answered

Any ideas. This principle could work along the same lines as an oil hot water heater pumped through a radiator (you know those 300 lb.+ radiators from older houses), but using the bulb in place of the hot water.. If it was portable, that would be great. I could make a nice cover or wood cabinet around it myself. What would be a good metal to line it with that could magnify the heat of a light bulb. Obviously, this would need to be a safe product. Getting a little warm on the outside is not a problem in our home. I mostly just need some idea as to what metal to use to magnify the heat of the bulb. Thank you in advance for any help or ideas.

Question by Lori216    |  last reply

New kind of SLS 3d Printer (german)

Hallo Community, ich habe die Idee für einen neuen 3d Drucker, der mit einer Laserdruckerkartusche arbeitet und ein Stützmaterial verwendet, das Streufähig ist.Gerne sende ich mein Dokumentationsentwurf (derzeit rd 13 Seiten) Interessierten zu. Sie trägt folgenden Titel:Die Additive Fertigungfür Metalle und Kunststoffe in Klein- und Mittelständigen Unternehmen für den Werkstattbereich- Aussicht auf ein Neues Verfahren -„ Leonardo Da Vinci und Nikola Tesla waren für mich die größten Erfinder, was würden Sie mit unserem heutigen Wissen für technische Wunder vollbringen?“ Hat jemand interesse sich daran zu beteiligen?

Question by zadouwe    |  last reply

How would I make a simple Infrared Heater?

I am planning on build ing IR Heater. would a 6 millimeter IR emmiter with 960 millimeter wavelength work to produce heat? If your not aware with IR heaters then here is a short explanation: A normal heater such as a gas heater heats up the surrounding air, but a IR heater uses infrared waves to heat up surfaces of objects. So instead of heating surrounding air the IR waves heat up surfaces of objects. Also IR waves penetrate the epidermise (top layer of skin). Here is a diagram of what the circuit looks like. The question is would this circuit work? Also are 6millimeter IR emmiter with 960 millimeter wavelength work?

Question by planetroverrobo    |  last reply

Electronic control for RV positive air pressure system..

I am biulding a positive air pressure system for my RV. I would like to include an electronic control system that will allow equal pressure inside and out or positive oressure inside. This will NOT allow any dust to enter the vehicle.I was thinking using an altimeter/pressure sensor for measuring internal and external air pressures. My concern is that the outside air flow while travelling will create a negative pressure reading.I also require circuit diagram for sensors cuopled to a 12v air blower.I look forward to comments and ideas.

Question by WAmaker    |  last reply

Bluetooth to landline phone

Hello, I would like to use the bluetooth headset I use with my cell phone for my landline phone at home. There are oodles of instructions out there on how to hack headsets to put them into old phones, I am looking for the opposite. Apparently Jabra used to make something that could have got me started (I believe it was called an A210) but that doesn't seem to be sold any longer. There are some wireless phones out there that incorporate bluetooth, but why add a battery operated wireless phone to a wireless headset - the bluetooth range would give me what I need to stay unencumbered. I have an old cell I could hack apart but I suspect that it would be tricky to get its bluetooth hacked into the analog phone line... Any thoughts? berserk

Topic by berserk    |  last reply

Can any help with commissioning a Prusa 3D printer with megatronics board.

I have completed the build but require assistance in testing and commissioning, can anyone help me, located in Perth, Western Australia.

Question by WAmaker    |  last reply

How do you make your own handmade paper "acid free"? Answered

While there are a few archival sprays that reduce the degradation and yellowing of paper after the fact, that is not what I'm looking for. I'm curious as to whether I can add something to the pulp in the process of handcrafting my own paper. I've heard that adding calcium carbonate while it's still in a slurry can neutralize the acidity of the lignin in the pulp. If so, couldn't I just throw a few Tums in there? And how much per batch?

Question by Asura-Valkyrie    |  last reply


HI everyone....i am not a professional artist.. just an amateur but I'd like to know your honest feedback and rating  :) thanks

Topic by madonna91    |  last reply

Collaboration Credit

I’ve recently collaborated on a few projects. Although the function works, it doesn't allow the co-author to get any credit. It seems like a simple solution would be to place the project on both author's pages. I see the question has been asked before without a decent response.

Topic by mtairymd    |  last reply

how to kill the loud annoying boom boom from cars?

i am wondering is there a way of over riding speakers to play my own music or just stop the boom boom coming out the car in front at traffic lights? i remember a broad band am frequency was mentioned once at one place of work but need your knowledge.?

Question by patternbill    |  last reply

Has anyone modified a Minn Kota trolling motor? Answered

I have inherited a pair of MK trolling motors that have been modified to the point that they doin't work any more. The pevious owner wanted to make them remote control, so he attached a receiver from an RC car and an electric gear motor was attached to the end of the throttle handle.  I think the soft rheostat has been damaged, so now it doesn't work anymore. In the attached picture we have a white soft rheostat with a cable to the controller. I believe the controller is okay. I think I want to attach a new potentiomoter to the cable to run the two motors. Has anyone worked on one before? Please don't ask me to ask Minn Kota. They are less than helpful. The board containing teh ribbon cable is no longer made. And the newer versions have one ribbon cable rather than two.

Question by vectorges    |  last reply

Lice, dust and Dandruff removing comb

The design of the comb is based on Vaccum based system as it will remove dandruff and lice using vaccum system. As per sketch there will be a vaccum pump and a rechargeable battery and both will be installed in the handle of comb. There will be several holes on the teeth of this comb to absorb the dandruff ,dust and lice When the Vaccum pump starts then the teeth of the comb will work to absorb the dandruff ,dust and lice atthe time of using this comb. Just use this comb and dandruff will be removed. Salient features: (1) it is simple to manufacture (2) it will work very effectively (3) it will remove dandruff and dust stick with hair to clean the hair so there is no need to wash the will also save time and money. (4)there is no need of any chemical as it will work using vaccum (5)The another interesting use of this comb is treatment of "Head Lice"as it will work to remove lice using vaccum. (6) It will be a low cost solution (7) There will be no problem of hair loss as there is no chemical.

Topic by vikram_gupta11    |  last reply

Is it possible to make your own electroplating solution?

Is it possible to make your own electroplating solution? Couldn't one simply toss some atomized copper dust from the sculpture supply store into a hydrochloric acid solution, and let it dissolve? If so, what other chemicals are necessary, and what approximate proportions should they be? I'm thinking quick and dirty here, specifically for electroforming medium sized objects. Thanks!

Question    |  last reply

led running brake light circuit for motorcycle?

i want to add 5 LEDs wired for 12 volt in parallel to my motorcycle running lights. then when brake is pressed they will light up brighter. i think i need to add a resistor to each input ( brake and running light wire) to drop voltage down. maybe 9 volts for running lights (which would be on all of the time) and another 3 or 4 volts for the brake light so added to 12 to 13 volts for bright brake lights. any ideas how do i do this and what size resistor i should use or am i looking at this wrong? 

Question by jmcgrath5    |  last reply

DIY Pilates Machine (sort of)

Hi,I was just wondering if anyone could offer me some advice or pointers, it would be very much appreciated.I love doing pilates. I used to so it a lot when I was a student but now I travel a lot and the machine (this sort of thing )is just too bulky to set up and put away.So I’ve been looking at alternatives, either something smaller and more portable or an alternative that would do the same thing. I found this but unfortunately it isn’t sold in the UK. Shipping a heavy item, paying the customs charge and then if anything breaks I won’t be able to get it repaired. So I am now trying to build something myself. I was thinking something along the lines of a skateboard or hoverboard with resistance bands clipped on. I was just wondering if anyone has any thoughts, suggestions or alternatives as I’d really love to hear them.Thank you.

Topic by Reddkryten  

Need help with code | Tactile device with stepper motor and audio files

Hello,I need help with my project involving stepper motor and audio files. I'm new to Arduino and I have very strict deadlines to meet. Can someone write the code for me? I can pay you for the same. Contact me if you're interested.

Question by abc3003  

Adjustable Teeth comb

My innovative idea is regarding an adjustable teeth comb. There are Many type of combs available in the market but problem is that one's cannot use all these types of combs at a time. There are wide teeth comb,semiwide teeth,and fine teeth combs are available in the market.To prevent the hair loss it is very necessary to find right teeth comb. The solution is here in this Idea. Discription: As per sketch there is a wide teeth comb and each teeth will have 1 with each other teeth. There will be an another comb which will slide on the wide teeth comb. The sliding comb will work in this way that the User can set the teeth of comb as per his desire or as per his hair style requirement. After setting the teeth the slider comb will be locked.In another words it will work like "Sliding Cutter mechanism". In this way this product will work. Salient features: (1) No need of buying different teeth comb as one's can set the space of teeth of this comb (0.5 mm to10mm) and this adjustable comb will work to prevent hair damage as it will not intangled with hair. (2) low cost (3) easy to use (4) light weight (5) easy to clean (6) Prevent Hairloss or suitable for all kinds of hair style. (7) Both Female and Male can use it. (8) very useful to detangle hair due to adjustable teeth for curly hair.

Topic by vikram_gupta11  

Arduino robotic arm

Hi, I just made a 5 DOF robotic arm and its not working for some reason I'm not sure whether if its the code problem or the mechanical part of the robothere's the Arduino code:#include #include Servo servo1; Servo servo2; Servo servo3; Servo servo4; Servo servo5; Servo servo6; int bluetoothTX = 11; int bluetoothRX = 12; SoftwareSerial bluetooth(bluetoothTX, bluetoothRX);void setup() { // put your setup code here, to run once: servo1.attach(3); servo2.attach(4); servo3.attach(5); servo4.attach(6); servo5.attach(7); servo6.attach(8); Serial.begin(9600); bluetooth.begin(9600); } void loop() { // put your main code here, to run repeatedly: if(bluetooth.available()>0) { int servopos1 =; int servopos2 =; int servopos3 =; int servopos4 =; int servopos5 =; int servopos6 =; Serial.println(servopos1); Serial.println(servopos2); Serial.println(servopos3); Serial.println(servopos4); Serial.println(servopos5); Serial.println(servopos6); servo1.write(servopos1); servo2.write(servopos2); servo3.write(servopos3); servo4.write(servopos4); servo5.write(servopos5); servo6.write(servopos6); } }

Question by RD0092  

Makerspace group contest on Instructable, anyone want to start a group with me?

The rules is quite simple, a group of 5-20 people will enter the contest, each member will publish any instruction on any project that he/she make. If the instruction is clear and good, it will get easybib feature in Instructable page. The team that has the most featured instruction will win the contest This is a cool contest that I think you guys might be interested. Beside, the prize is freaking awesome. I'm doing a project to post, and I have won a runner up prize on the page before, so I'll say it's possible. Btw, the group just need 15 featured post will receive a prize so I think it's worth a shot fedloan

Topic by joshuapaul131129  

How to program the XS3868 bluetooth audio module through arduino?

Hello, I have a few of these xs3868 bluetooth audio modules that I used in some speaker systems I built for myself, but now one of my friends wants me to build him a custom speaker with a custom bluetooth device name and passcode. So I thought, ok, I read a little about programming with the AT commands but never tried it before, so I hooked up a board to 3.3 and gnd of the arduino like I usually do to check before soldering everything, my phone connected with no problem. So next I turned off my phone's bluetooth so it wouldn't mess with the chip while programming it and connected the rx and tx pins of the board to tx and rx respectively. I also made the following adjustments in the arduino serial interface that I remember reading somewhere: No Line Ending, and 9600 baud rate. Plugged in in to the tx and rx of the arduino board with at mega chip removed and had no luck getting any response from the chip, I switched baud rate to all of the different baud rates available with no success, the only effect the chip has on the serial interface is that when the power cord slipped and I plugged in back in with rx, tx and the usb cable still connected it output a few seemingly random characters while (I'm assuming) the chip was booting up, at 115200 baud rate the characters were a "u" with two dots over it and a combination lowercase "b" and "p" (for some reason I can't copy/paste it). It only outputs these characters when one of the power wires is reconnected after being disconnected (I have a bunch of these so if I fry one it's no big deal). I tried connecting my phone again after a while and it worked, checked the wires with my multimeter and both are connected and neither is shorted to any other pins and switching rx/tx does nothing to fix the problem either. I have a usb to serial coming in the mail soon hopefully but my friend was hoping this could be finished sooner than it would arrive so any help would be greatly appreciated. Edit: Is it possible that the module could have a rs232 interface, rather than a ttl interface? I've heard that arduino only uses ttl and that I'd need another adapter to get to rs232 since my computer doesn't have that kind of serial interface.

Question by LazyH    |  last reply

Knex ball factory instructions!

I have the PDF files for the BIG BALL FACTORY!Here they are! if this violates anything, just PM me and I will take it down. YAY!

Topic by Bartboy    |  last reply

Which wood would be good for making a crossbow??

I want to make a crossbow, not a proper one one, just a toy one so that I can have some fun. However, I'm not sure which wood would be best for the bendy bow bit. I'm located in England, and I would like an easily accessible wood to make it. 

Question by Crafty Dragon    |  last reply

How to make a huge hollow sphere?

I am planning on a project and I need to know how to make a huge hollow sphere? I was thinking about using paper mache around a huge sphere, but dont know where to start, like what would i paper mache around. I would like the sphere to be about 30"-40" in diameter. Even though Ive said it, please remember it needs to be about 30"-40" before you answer your question. Thanks!

Question by Hiyadudez    |  last reply

How do you build a successful working time-machine?

What materials do you need to build a time macchine? How much energy? And how do you controll it? Can you give me some backround knowledge?

Question by awesomo3000    |  last reply

How to control the temperature of a peltier module?

What is the most efficient way of controlling the degree of hotness or coldness of a 12v 6A peltier module? Can I use PWM?

Question by Jayvis Vineet Gonsalves    |  last reply

15W laser

Help help help! Ive just fitted a 15w laser to my cnc 3018 and I cant get the laser to switch to low power mode. It just wants to burn everything! How do I fix it? Ive attached two pictures, one of the laser and one of the board. The board is a woodpecker GRBLO 9. Please if anyone can help me I would be eternally great full.

Topic by MattK171    |  last reply

How many mAh = 1 farad?

Question by 7654321    |  last reply

what kind of filter would I need to filter out solder fumes? Answered

Would i need a HEPA filter or could i just make a little thing that fit's on a box fan and holds a bunch of activated charcoal. i live in the great up north so i can't open my windows to let the smoke out and doing it in the shop is out of the question because it's so drafty it can't hold heat at all. I'd like to be able to set up a soldering station in my room but the problem with that is the smoke being too noxious, it'd freak my parents out. do they make actual specific filters that can hold onto all the smoke? or is it more along the lines of getting mostly everything but never quite being able to get it all?

Question by waldosan    |  last reply

Direction microphone questions Answered

A few days ago a friend gave me a directional mic he used with his camera.Of course I don't get these things as a working present but to repair them :(Anyway...Taking it apart to expose the inside was the first nightmare as for some reason my friend decided to use a splash proof mic on a totally unprotected cam.If you ever tried to take one of these aquarium tube heaters apart you know what I mean...To my surprise this formerly expensive toy failed due to a bad solder connection, easy to fix.And lucky as well because the actual microphone capsule was glued in place pretty good.A quick test on the computer with the supplied microphone amp showed it worked fine again so I wanted to find out how it actually works.They toy ones use a half sphere or mini dish to reflect the soundwaves onto the mic.My friends however was an aluminium tube of about 20cm lenght.15mm in diameter with the mic being just 5mm and sitting in what seemed to be the end of a little funnel inside the tube - right at the end.So in theory I would now just say the thing gets what comes in from the front, but well that would be far too easy...When I pulled that fluffy sock off the mic I realised two weird things:6 small holes going straight through the mic funnel and outer tube.A glued in relatively soft plastic sleeve with a wave pattern.It seemed this pattern changed on the way down but I could not really see inside properly.Closing the front hole and the mic had no problems getting all sorts of noise from all directions, quite lower in volume compared to a direct hit from the front though.Closing the small side holes with some tape and the mic is still very directional but also really noisy.It seems some acoustic magic is happening in the tube.No real clue though but I guess the sleeve acts like the sound dampening in a test room.Without it all sound entering the tube would reach the mic, while with it really only a very tiny, front facing angle is able to reach the mic.The aluminium certainly transmits some sound onto the mic and the glue appeared to be rock hard as well.So I have to assume that the sound entering through the tiny holes somehow cancels out the noise transmitted by the tube itself.With just 15mm in diameter however I can calculate what I want but am unable to get any true 180° phase shift happening.Looking up how other types of directional microphones work was a bit helpful here but not so much in understanding the holes and liner.My friend said it is well over 30 years old and that he got dirt cheap at a garage sale.No markings anywhere and the small amp only has the connectors for mic, power and output.Did not check the circuit board inside as the housing was glued together.So:Why holes in the side right at the height of the mic?Why does it "hear" all surrounding sound when the front is closed but only directional with the front open?And I mean directional even with some music playing close the mic :(By the way: Battery pack for the mic was the classic four pack at 6 Volt.

Question by Downunder35m    |  last reply

Is it possible to use router bits (6.4mm) for rotary?? Answered

Hey guys my first time post here:3 As you can read from this topic, is it possible to use router bits(6.4mm) in rotary?? like using extension collet or something?? I found some information on the internet that it is not good idea to do so considering the power and so on, however I would like to know if there is any way that to make it possible to save some monet.... thank you

Question by diydaiku    |  last reply

Is it possible to connect 2 motion sensors to a two way light?

I want to add 2 motion sensors to my staircase lights, but in the same time be able to control them from two switches. One at the bottom and one at the top of the stairs. Is that possible?

Topic by KarimGawish    |  last reply

Solar powered backpack options?

I would like to create a backpack/rucksack that can properly charge a modern cell phone with enough to spare or a MP3 player or small GPS.Preferably something that works while riding a horse for week long adventure trips.Standard solar cells are not just quite rigid and heavy but also relatively fragile.Flexible panels seem to be the alternative but price and power levels mean going well above the size of a standard 12V/10W panel.And even getting those standard 25 by 35cm on average fitted onto a modern backpack is no easy task.Trying to do so and getting the full 10W out is next to impossible it seems.The theoretical 1000Wh on a 10 hour, sunny day for such a panel would go don to a realistical 100Wh hours at best.Nowhere near enough to fully charge a hungry phone with a 4000mAh or bigger battery.At least not if you really need a quick chage and consider a realistic environment.Means a 2 hour quick charge at home might take 5 hours or more when hiking or riding a horse through the bush.A foldable or roll up panel when having a break or camp might be nice but not if it would mean carrying an extra solar panel.The most logical conclusion would be to integrate solar cells into the clothing as well.sadly technology is not that far yet :(So, how could a solar powered backpack or similar be created that is not too big and still capable of providing at least 5-6W under not so perfect conditions?And preferably with at least 10W no matter how it is placed into the direct sun with the panels.How could it be made possible to utilise the sunlight if you are facing the sun with the backpack, well, on your back?What types of solar cells in terms of technology and being available would be best suited for such a rough application?

Question by Downunder35m    |  last reply

Is it possible to use router bits (6.4mm) for rotary??

Hey guys my first time post here:3 As you can read from this topic, is it possible to use router bits(6.4mm) in rotary?? like using extension collet or something?? I found some information on the internet that it is not good idea to do so considering the power and so on, however I would like to know if there is any way that to make it possible to save some monet.... thank you

Topic by diydaiku  

Battery less mosquito catcher Bat

There are products like battery operated bats available in the market to kill mosquitoes and insects but there is no battery-less innovation. My invention is very simple and very effective in killing mosquitoes as there is no need for recharging the battery of this mosquito bat. Only a bat and adhesive tape are required to build it. It will work to by trapping and killing mosquitoes. Salient features: (1) there is no need for recharging it. (2) the adhesive tape can be removed and replaced after use. (3) it is a very low cost design so anyone can afford it very easily. (4) it is safe and light weight (5) it can be used many times.

Topic by vikram_gupta11    |  last reply

Simple solution to prevent load swinging in overhead crane

Cranes are used to move loads from one location to another in minimum time such that the load reaches its destination without swinging. As we all know, that swinging problem occurs due to flexibility of wires but if the wire is rigid and permanently fixed on one side then ???As per the sketch there will be a telescopic arm and one side of the arm will be attached with the trolley of the crane. This rigid telescopic arm will be connected with the load at the time of lifting the load. In this way there will be no problem of swinging as the rigid telescopic arm will be fixed with the trolley and wires will work to lift the load so there is no chance of swinging of load.My solution can achieve these following points at the time of construction.Improved Safety High-Precision Moves Increased ProductivityEasily Implemented on Existing tech Save time Save energy to reduce carbon Cost as the crane can work at the time of high speed air. My solution is simple, low cost and very effective to prevent load swinging problem.

Topic by vikram_gupta11    |  last reply

P.E. class electronic prop.

Looking for someone who can help me building a agility/footwork timer or creating the schemeplans for it so it can get to work. Found on YT :( for sports like badminton and in P.E. lessons (sportsagility)One controler that choose the direction left/right and times each time the reaction-time.Timing after 10 runs or as preset is shown as the average time. Endresult for youngster.I'm creative in P.E. but not in arduino.....therefore; Heeelp please!!

Topic by wernerbroos    |  last reply

Paper Shredder won't stop Answered

Ativa MDM 8000 in auto mode should time out and turn the motor off after last shred but no longer does this, just keeps running. Took apart and cleaned all sensors but did not help. Checked all wiring, looked OK.  Any ideas how to fix ? Must be a problem with circuit board.

Question by phantom9    |  last reply

What led driver do I need for a pcb

Hey, I am going to purchase a led pcb, Its 90 watt one & I need to know which driver I need.The pcb is 90w 30v & 3000ma & can be run without heatsinkThe model is Invisible sun led ISH150- pcb.I have seen a driver online & it's rated the same 60/70/90/100 w & 30 volt & 3000ma constant current.Is this the correct driver for that pcb ? Thanks

Question by Samille78    |  last reply

Car Battery

When I tried to start my  car the ignition just clicked a few times, then finally started.  It seemed like the battery was weak.  I spoke to a mechanic who said probably one battery cell was bad and advised that I replace the battery.  I did that and now have a brand new battery. I didn't fix the problem.  Does anyone have advice?

Topic by BdaSpidey    |  last reply

Alternative Nuclear energy

p.MsoNormal, li.MsoNormal, div.MsoNormal { margin-top: 0.0in; margin-right: 0.0in; margin-bottom: 10.0pt; margin-left: 0.0in; line-height: 115.0%; font-size: 11.0pt; font-family: Calibri , sans-serif; } p.MsoHeader, li.MsoHeader, div.MsoHeader { margin: 0.0in; font-size: 11.0pt; font-family: Calibri , sans-serif; } p.MsoFooter, li.MsoFooter, div.MsoFooter { margin: 0.0in; font-size: 11.0pt; font-family: Calibri , sans-serif; } p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph { margin-top: 0.0in; margin-right: 0.0in; margin-bottom: 10.0pt; margin-left: 0.5in; line-height: 115.0%; font-size: 11.0pt; font-family: Calibri , sans-serif; } p.MsoListParagraphCxSpFirst, li.MsoListParagraphCxSpFirst, div.MsoListParagraphCxSpFirst { margin-top: 0.0in; margin-right: 0.0in; margin-bottom: 0.0in; margin-left: 0.5in; line-height: 115.0%; font-size: 11.0pt; font-family: Calibri , sans-serif; } p.MsoListParagraphCxSpMiddle, li.MsoListParagraphCxSpMiddle, div.MsoListParagraphCxSpMiddle { margin-top: 0.0in; margin-right: 0.0in; margin-bottom: 0.0in; margin-left: 0.5in; line-height: 115.0%; font-size: 11.0pt; font-family: Calibri , sans-serif; } p.MsoListParagraphCxSpLast, li.MsoListParagraphCxSpLast, div.MsoListParagraphCxSpLast { margin-top: 0.0in; margin-right: 0.0in; margin-bottom: 10.0pt; margin-left: 0.5in; line-height: 115.0%; font-size: 11.0pt; font-family: Calibri , sans-serif; } span.HeaderChar { } span.FooterChar { } *.MsoChpDefault { } *.MsoPapDefault { margin-bottom: 10.0pt; line-height: 115.0%; } div.WordSection1 { page: WordSection1; }   Alternative  Nuclear energy. Our main source of  energy right now is nuclear energy. Although Nuclear energy  might seem to be a reliable source of energy, it is not.  Nuclear energy is not a reliable source of energy  because you need to extract Uranium ore from the earth's core which might seem as a good  source of Uranium it is not. This is not a endless supply  of uranium because it will eventually  run out of uranium .   So what can we do to solve this issue? The answer is alternative energy.  Alternative energy  is energy that can be renewed  and that is reliable. One solution is replacing Uranium fuel rods in a reactors core with Tritium. Tritium can be used  as a substitute for uranium because it has the same properties as uranium except that it has a shorter  half life.  Tritium is made by fusing solid  Hydrogen With Lithium  in a Farnsworth reactor.  This also has its problems one major  problem is the radiation and heat that is generated during the process  of fusion. Tritium can be then used as a fuel  pellet for a Nuclear reactor when it is mixed with Deuterium which is a solid. Tritium is also a good fuel pellet because it only has a life span of about 12.4 years, then  it decays into Helium 6 which is very harmless. Uranium on the other hand is not  safe because it has a life span of about 2000 years and it gradually decays into other radioactive material such as Thorium, neptunium, ECT.... This is Called the Uranium - Thorium cycle. The tritium is also ecologically friendly because it  can be made from H1 which is found in water H2O.  H1 is called Portion and is extracted through a process called electrolyses in which water is charged by a D.C current.

Topic by dciocoiu    |  last reply

How can I track my car GPS position on home PC?

Hi, I got GPS fitted in the car. Is there any way I can trace my car position on my computer screen at home?. For example, while I'm driving on the road, Is there any way my family members can see my car position moving in real time on Google maps. If yes what sort of hardware or softwares required. I would appreciate any pointer or help. Thanks in advance. Kevin

Question    |  last reply

Need help in debugging code for 4x4 keypad

Greetings, I am relatively new to this forum. Please pardon me for any mistakes I make while posting new topic in this forum. With this being said, I have been trying to write a 'standard' 4x4 keypad scanning code. However, the code did not work correctly, I have tried to debug my code using the Serial Monitor with no luck. According to the Serial Monitor, only few keys would actually be correctly registered (usually 5, 8, 4, and 1), and the rest give me no output at all. However, when I insert a delay of 1 second within the loop itself, all the keys are correctly registered, but it give me a 'cyclic' pattern (ie. pressing 7, will give me 1, 4, and then 7). I have spent a lot of time on this, and a Google search of 4x4 keypad always refer me to the Arduino library. Overview of the code:set column pins to pull_up resistor, and set the row pins as output. Begin to scan the column pins with a given row pin output, and return the index.*Note: I know there is an Arduino library for this, but I want to practice in coding/programming the 4x4 keypad, and I don't know where did I went wrong.const byte ROWS = 4;const byte COLS = 4; int rowval; int colval; char hexaKeys[ROWS][COLS] = {{'1', '2', '3', 'A'}, {'4', '5', '6', 'B'}, {'7', '8', '9', 'C'}, {'*', '0', '#', 'D'}}; int rowPins[ROWS] = {7, 6, 5, 4}; int colPins[COLS] = {3, 2, 1, 0}; boolean col_state; boolean prev_state; void setup() { Serial.begin(9600); for (int i = 0; i < 4; i++) { pinMode(colPins[i], INPUT_PULLUP); pinMode(rowPins[i],OUTPUT); digitalWrite(rowPins[i],HIGH); } }void loop() { for (int i = 0; i < 4; i++) { rowval=0; colval=0; pinMode(rowPins[i], OUTPUT); digitalWrite(rowPins[i], LOW); for (int j = 0; j < 4; j++) { col_state = digitalRead(colPins[j]); if (col_state == 0) { prev_state=col_state; delay(50); if(digitalRead(colPins[j])==prev_state){ rowval = i; colval = j; Serial.println(hexaKeys[rowval][colval]); delay(1000); ///add a 1 second delay here to make the output of Serial monitor more manageable digitalWrite(rowPins[i],HIGH); pinMode(rowPins[0], INPUT); break; } } } if(rowval!=0 && colval!=0) break; } }

Topic by Arthur091    |  last reply

2000watt bulb

How to make your own 2000 watt light bulb.

Topic by pritishs4    |  last reply