Automated Garage Door Timer

I have the bad habit of leaving my garage door open sometimes. To come home with your garage wide open is pretty scary. So I was thinking of this idea...  The garage automatically closes after 5 minutes. But that's pretty annoying so I figured you could install a switch underneath the garage door opener that will leave the garage door open. Any ideas on how this could be done or more suggestions? Thanks!

Topic by BrianKT    |  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

how do you harvest platnum from old hard drive platters ?

I know most hard drive platters have a thin sheet of platnum . how do you seperate the platnum from the non precious metal?

Question by mrdmburns    |  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

i need help to make a video game can anyone help me?

Hi my name is arshya and i want to make a video game but i do not have the experience because i am 13 but i already have a idea i just want to see if it is possible to make it so if any one can help we can work as a team if its possible to make my idea, we can get it together than maybe we can split everything 50, 50. so if anyone is interested just email me at

Question by arshyamohebpour    |  last reply

12v brake and tail lights?

I'm trying to build a brake/tail light out of LED's for my motorcycle. How do I make the red brake lights brighter than my red tail lights? I'm using 3mm 12v (resister pre wired by supplier) and/ or have similar 10mm lights available too.

Question by dthing    |  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

Unable to upload Arduino sketch

As the title. Every time I try to upload and Arduino sketch (i,o file) as part of an instructable I get an "Internal Server Error". What am I doing wrong? Image files uplaod without problem. Thanks

Topic by techno-womble    |  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

Quick question regarding car stereos and speakers? Answered

Hi, so I was thinking of buying a new stereo (receiver) for my '97 Mitsubishi Mirage DE, along with some speakers (mine are crap). When I go online (such as, I run into some confusing descriptions. The receivers are usually rated as 200W for four channels (it'll then say like 50W x 4), whereas some of the speakers say "100 Watts Peak 50". I think I only have two speakers on the interior of the car (driver and passenger). Does this mean I can buy speakers with a higher wattage? I'm guessing the 50W x 4/ 200W over four channels means that it's 200W of power/audio for four interior speakers. Does having less speakers give me a greater allowance for speaker power, or will less speakers put more strain on the ones that I install (200W getting split over two channels instead of four)? For reference, here is the receiver I'm looking at, along with a pair of speakers I found that fits the "Peak 50":;=219598_0_0_;=219603_0_0_&viewAll;=true

Question by Hadokendude    |  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

DPScope software

I have an old DPScope module that has worked with Windows XP. The software I have does NOT work with Windows 10. Has anyone got working software?

Question by david-beit-ezra    |  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

How do I enter my instructable in a contest

I have tried to enter my instructable in a contest but I do not know how to check if it was sent in

Topic by Basketball2573    |  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

What is the difference between PVA glue and Elmers glue?

What is the difference between PVA glue and Elmers glue?

Question by threadbare    |  last reply

Can LED's in Gemmy Kaleidoscope Light be replaced?

I'm trying to re-purpose a Gemmy Kaleidoscope Green LED light bought last year for outdoor christmas lighting. Is it possible to replace a couple of the LED's in it and make it a multi-color unit (RGB) instead? Here's what the innards looks like. Not sure where I can get the LED part numbers to look them up. Thanks for any help.

Question by joe_renaud    |  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

Does anyone know how to dry a liquid to make a powder?

 I want to make stevia powder out of a concentrated stevia liquid? To store it longer and to use it in dry tea mixtures and so on.

Question by hugenott    |  last reply

Removing hair dryer heating element

Request for help:  Does anyone know how to remove the heating element from a hair dryer to have it only blow cold/cool air?  I've opened it up and there are a lot more wires than I expected.  I have just enough electrical knowledge to be a little bit above dangerous, so I thought it would be best to ask for help.  Thanks!

Topic by WaffleM    |  last reply

How can i connect my car stereo to powered speakers?

I have a pair of edifier R1280t powered bookshelf speakers which sound great. They have two inputs and i use one of them with my pc. I have a car stereo lying around and would want to hook them to the other input on the speakers using a psu. But my question is, can i connect powered bookshelf speakers to my car stereo? I have rca connections on the stereo and i think i can connect them but i am not sure. Please help me. Attached is the stereo wiring diagram in the manual.

Question by Mohanponnam    |  last reply

LED text matrix strip.

Hi, I am very intressed in making a LED text strip. Any ideas how? Please see attached photo.

Topic by Havin    |  last reply

IR helicopter doesn't respond, how to fix it? Answered

Hello, I have here a (G.T. MODEL 9004) helicopter that worked fine for 3 years maybe, now I just wanted to use it again in one of my projects, so I went to Shake out the dust of my old toys, and didn't respond to any thing ! I charged it, and tried again and nothing except its internal LED blinking when I try to give a command from a transmitter. So it seems to receive but doesn't take an action ! (Note that you may see that it's important : When I used to use it, I was providing it the power through a 9V power supply because batteries were very coasting and get dry fast due to its usage in the helicopter charging, but it always worked fine.) It's company link :

Question by Hawk-Eagle    |  last reply

how do i make a fuelless generator?

I mean a generator that runs on free energy source

Question by lokoboy    |  last reply

Energy efficient, waterless, Copper strip based cooling system

Energy efficient ,waterless Copper stripe based cooling system:The presented Idea is based on Heat exchange principle.As per sketch there will be a conveyor belt system and some copper stripes will be connected with this belt.Each copper strip will have a moveable hook.The conveyor belt will move with a motor.Each copper strip will be separated with each other and with conveyor belt with the help of Insulation (wooden insulation).Each copper strip will be connected with the machine for 15 to 20 seconds to absorb the heat and after that this copper strip will be removed and next copper strip will be ready to absorb the heat.The removed strip will be cooled down after some time and will be ready to couple with the machine again.In this way each copper stripe will work one by one to absorb the heat to cool the machine and each strip will get cool down due to convection .What I thought is that if I use a continuous water jet to cool the motor then the motor will remain cool so if I use the copper stripes then the same effect will be occured.It will work in this way that temperature will be not increased of machine if I couple the device with the machine. It will be low cost,low maintenance,waterless solution to cool the machines. It will consume almost nil energy

Topic by vikram_gupta11    |  last reply

Rust on sink drain pipe

HI,I have noticed this year that the exposed drain pipe from my bathroom sink is rusting badly, turned all green. Why is this happening? Anything I can do about this? I guess I should replace the pipe, but this will be complicated cause it is going into the tile floor and the cent under it. Any advice would be welcome.Thanks

Question by Veters    |  last reply