Laptop Fan Buzzing? Answered

Hello Everyone, Need some advice here. I have noticed a slight buzzing sound in my fancy gaming laptop's fan recently. Its only audible when the fan is on its highest speed and then you wouldn't notice it if your volume is up. I'm fairly certain the problem is that the fan is slightly off balance. Here's why: 1). I completely dismantled the laptop and cleaned it of all dust and particles, so its not clogged or impeded in any way. 2). The sound stops if you tilt the laptop approx 30 degrees in any direction. (The sound actually gets louder until the 30 degrees is reached, then it completely stops). My question is: What should I do about it? Is it really much of a problem? Do I need to replace it? If I do, my warranty literally expired 1 week 1/2 ago, is there anything I can do about that? I feel cheated by the timing personally.

Question by transistorguy   |  last reply

LM386 amp buzz? Answered

Should be an easy question :-) I built my first 386 based amp, and it works great, except for input volume control. Almost every schematic has 10K pot at input (connected to pin 3 on 386). Problem is when I turn pot all the way down I hear buzzing noise, especially if source is off. Also it doesn't cut source volume noticeably so I tried using 10M Pot, and it works except buzz is now super loud. So how would I control volume? 

Question by bratan   |  last reply

LED Lamp Buzzing (not a bulb)

About a year ago, I came across this LED lamp that was on sale at my local Target store. It caught my eye because it had a little tray at the base of the lamp along with a USB port for charging my devices. Since the first time I plugged it in and turned it on, it makes a buzzing noise. At first it didn't bother me, but now that I am spending more time at my workbench it has become annoying. I understand it is kind of common for LED bulbs to do this because of the dimmer switch being outdated, however this lamp is not dimmable nor is it a "bulb" so to say. It's about 7-9 SMD LEDs on a circuit with a rocker switch. If it makes a difference, I do have my lamp plugged into a surge protector and don't have anything plugged into the USB port located at the base of the lamp. What can be done (other than throwing it away, of course) to stop the buzzing noise coming from the lamp? Thanks in advance!

Topic by TXVisual   |  last reply

electromagnet gauge makes buzzing noises?

Hi, i've been working on a project that involves reusing the electromagnetic needles commonly used in 90's era ford gauges. i can get it to work fine, but it seems to cause a buzzing noise as it is doing the work. there are three pins, ground, power, and signal. right now i just have it working off of 5v. when i have it going, and you hold the needle with your finger, you can feel it vibrating. i'm using an arduino nano, a npn transistor, and the gauge with a PWM output. do i just need to put a capacitor in? or how do i keep it from buzzing like it does? its not a loud buzz, but you'd notice it if you were in a quiet room.

Question by zack247   |  last reply

My NST is buzzing- how do I stop it?!?!?

Hello, I am in the final steps of perfecting a Tesla Coil that I started a few months back. I only got the spark gap to fire in one test run. Every other time, the circuit does nothing, and my new 10 kv neon sign transformer buzzes loudly and ominously. I'm really worried that I'll burn it out. Why is it malfunctioning? How can I fix the problem?Update: After a little experimenting, and checking all connections, I've found that the one time that the spark gap fired happened because of a wiring error (i connected the gap in series to the transformer instead of parallel); this resulted in a spark across the gap, but no oscillation. I'm starting to think that the capacitor's are the problem. I originally believed that the required capacitance was .003 uf, but I recalculated that and found that it was actually .0079 uf. This could explain why a spark couldn't jump. I'll order some more, and see how that goes. Thank you all.

Question by ElectricUmbrella   |  last reply

Need a schematic design for a simple circuit.

I was wondering if anyone here could help me design a particular circuit. The "device" would need a single button. When said button is pressed a buzzing sound would occur ( kinda like in game shows, you know that wrong answer sound?) then wait for five minutes and automatically buzz again by its self. Press once (BUZZ) wait 5 minutes buzzes again without the need to press again. I am perfectly capable of reading schematics and building prototype circuits. I just have no "nack" for design as of yet. Any help on this issue would be greatly appreciated. Thank you for reading my post. PS: I am a little rusty on some of the symbols, therefore a legend would be great.

Topic by ClaynEva   |  last reply

How to eliminate PWM noise at slow speeds when using a PC fan? Answered

My power supply has a cooling fan inside. I wanted to slow it down to reduce the fan noise. When i use this circuit in the picture the PWM works great except for the low speed buzzing. Turns the fan into a speaker. Is there some way to eliminate the buzzing?

Question by WWC   |  last reply

Circuit with Thermistor and buzzer?

How do I build a simple ciruit that will cause a buzzing sound when the temperature rapidily increases?

Question by Emmsie   |  last reply

How would I add a timer to an alarm system to let it ring for a set period of time? Answered

Http:// Basically trying to add a timer to this alarm so it doesn't buzz until the battery is dead. I just need to know what parts I need and to wire this to that.

Question by Peace_Maker   |  last reply

very strange speaker amp problem?

I have two 5v speaker amps. One i made myself and another I got from my cousins junk box. Anyways, when I connect the speaker it has a very very loud buzzing. The strange part is when I touch almost any terminal in the circuit with my finger the buzzing stops and it plays normally with very little buzzing. The amp I made I have followed the circuit schematic exactly and triple checked everything. I have tried grounding the parts too but that didnt work so I know its not a grounding issue. Another thing, while I was making the amp I tested it and it did the same thing but it started working when a 10k resistor popped out of its place and was sticking straight up in the air, it was originally connected to ground. please help.

Question by fossilshark   |  last reply

how do i fix an mp3 player head phone jack?

I have an ipod and when i try to put the headphone plug in it falls right out buzzes and it is not the headphones

Question by ninjaspartan   |  last reply

Can anyone help me troubleshoot my amp?

I recently built an amp using lm386 ic. It works really well but it makes a buzzing sound while playing and while ideal with no input and power on.

Question by Ankan Nayak   |  last reply

Servo Help!

First of all, I'm not the best with Technology projects, just putting it out there in case its an obvious answer. Anyway, I have an arduino project that im working on. All it is is a servo that spins after 24 hours, I thought it would be a simple project (I've worked with arduino a little bit) and I wired it up correctly, I'm sure of that, but after I coded the program, the servo wouldn't spin! It just made a dull buzzing sound. At first  I thought it was my program, so i tried just about every basic "sweep" program i could find online about servos. Every program had the same result, a faint buzzing sound and no spinning. Next i thought, maybe the 5v wasn't enough to power the microservo, so i used a external 9v and ended with the same result, buzzing, no movement. Can Anyone Help me?! Please! Is it just a simple solution? Or is my arduino micro controller not working! Please help me because i would like to enter the project in a contest that ends soon! Thank You!

Topic by Waztsn   |  last reply

annoying feed back need help getting rid of it ? Answered

Ok so i have an old guitar amp with 2 car speakers and a drill battery and a car inverter. somewhere in this line im getting feedback   like buzzing and it sucks   i made this thing in hopes of having a really loud back pack sound system and it worked very well but the feed back needs to go i dont know what causes it but i know it has something to do with the way im powering it because when i use a wall plug instead of the inverter it stops the buzzing but how do i fix it for good

Question by kylejjjjj   |  last reply

3 "working" microphones not working on any of my two computers?

This is the weirdest thing ever. It's my laptops internal mic, a 5$ mic and a 15$ mic I just bought a couple of hours ago. My main assumption is they are buzzing so much that my voice is being cancelled off by my computers. On the 15$ i can hear very loud buzzing and even my voice over it. But on the other two absolutely nothing. Thinking it was a grounding issue I tried taking my laptop everywhere in my house, but the results are the same. They appear to work fine in a distance from the building I live in. Is my house cursed or what?

Question by N.Khan   |  last reply

Guitar Amp Static

Following up on my other thread with soldering, I managed to get my circuit for a distortion pedal all wired up.  I've got the clean end working, and nothing at all on the distorted end, but I'm not concerned about that just yet.  On the clean end, I get a really annoying buzzing sound, like when you turn the amp on with a cable plugged in with no guitar on the other end.  What would be cause of this?  Possibly outside interference since I haven't actually put this into an enclosure yet?  This is the schematic I followed.. and the sound from my amp is similar to this.. No, it's not the amp that's the problem because it works fine without the circuit.

Topic by MGZero   |  last reply

Piezo buzzer won't work? Answered

I have a couple of Piezo buzzers that I bought from the Adafruit shop, but when I connect them to a power source, they don't buzz or make any noise... Am I doing something wrong? Or am I not doing something?  Heres the link to the buzzers I have:

Question by Zem   |  last reply

Want to make a Light-up Timer, Looking for help/information?

I work with students that are disabled. Several are deaf. I would like to make a small timer that lights up or blinks instead of buzzes. The timer would need to be small like hand held size. If there is anyone that could point me in a direction... OK, the right direction. Thanks

Question by Troy65   |  last reply

How to make a game timer with 3 timer settings (1min, 45sec, 30sec) that will also buzz when the time is up?

I know nothing about circuitry and am trying to make this simple timer for a game idea that I want to produce. Instructions on how to build this or directions on who I could talk to about getting this mass produced would be great! I appreciate any help. 

Question by AndrewR259   |  last reply

Olympus fe-310 doesn't work?

Mu olympus fe-310 camera refuses to work. It will turn on, but as soon as i press a button, (including the off) is starts to buzz, and the screen goes black. The only ways to get the lens in is to take out the batteries, put them back in, and take them out at just the right moment. I NEED it for the instructables that i want to post. Please help! 

Question by freeza36   |  last reply

Google Tablet Information

There seems to be quite a lot of buzz about the (rumored?) Google Tablet but I am unable to find any information that is all that useful like specifications, an official Google webpage for it, an official announcement of the product by google, etc. and so was wondering if anyone knew anything about it or had any links relating to the aforementioned topics.  If so, please post them here and this forum should help to clear up some of the frenzy and confusion surrounding the tablet.  Thanks!

Topic by UbuntuNinja 

DIY generator

I'm new to this forum. I just got my welders certificate. I've seen on the web some projects that convert an auto alternator to a 300 amp welder. I live in an apt. and don't have 220V. I have a new mig welder and it works super for thin and medieum guage metal. My buzz box needs alot of power, about 15 KW, and even used generators are out of my range. Can anyone help?

Topic by CraigLam   |  last reply

Circuit board assistance for a beginner (corded phone hack)?

I'm attempting to hack an old corded phone into a two button device in a smaller enclosure. Reason being my apartment uses landline phones to buzz people into the building, and I wanted to see if I could DIY a fun alternative. As it stands the functionality of two buttons is needed - speaker to answer/hang up, and the 9 key to buzz in - but the board itself is larger than the enclosure I had wanted to put it in. Is there a way to get around this? Would it be a matter of having to trace the circuits and physically break off pieces of the board that aren't relevant (keys 1-8, etc), or do I have it all wrong?  Pictured below is the board and the two buttons in question. EDIT: I accidentally circled the key below the 9 key - I'm aware of this mistake. I am a total newbie when it comes to this stuff so if this is a dumb question I apologize in advance. Additionally, if anyone has alternative solutions or suggestions for this issue I would love to hear them. Thanks!

Question by Flip175   |  last reply

An electric fence?

I've got a couple of love birds in a big cage in my porch.But the things is that,this ugly black cat keeps constantly appearing out of nowhere and frightens these poor birds.The cat also makes attempts to grab them.I am asking for aid here cuz I know something a bit buzzing can keep the pussy off,anyone any bright ideas?(probably a helpful instructable).A security system which detects the villain and alerts me can also be effective.Any help would be greatly appreciated

Question by Adarsh_tronix   |  last reply

555 1 Hz pulse generator? Answered

Hi,I have a simple buzzer which I want to convert to an oscillating buzzer so as to obtain the sound similar to that of an automobile's reverse indicator.I've posted a schematic(borrowed from below.I intent to replace the LED with my buzzer and omit the resistor.I hope by building this circuit,to make my buzzer 'buzz'(or make noise) at an interval of 1 second(since its a 1 Hz pulse generator).Would the results be similar to my needs?

Question by Adarsh_tronix   |  last reply

Diagnose 2.1 Speaker Subwoofer Problem?

I picked up this 2.1 Edifier M3300 Speaker set at the Goodwill cheap. The Right RCA connection doesn't produce any sound except for a buzz. The left connection is fine. I check the speakers and they both work when plugged into the Left connection.  How do I figure out how what is wrong? Could the amp be broken or just the connector? I don't mind just 1 channel, but if I could fix it, I would like to try. If it's too complicated, I'll just leave it alone.

Question by phillyj   |  last reply

How do you fix an LCD monitor that appears to be fine when you turn it on but then turns black after about ten seconds?

The monitor shows picture when you first turn it on, but their is a weird buzzing sound in the back. After a few seconds the screen goes black and the sound goes away, but the green light stays on. It may be the backlight, but I have not been able to take the cover off (unscrewed all the screws but the case will not come apart, neither does the base come off). Any advice ("good advice") would be helpful. Monitor: HP L1706

Question by Insect   |  last reply

How can I build a giant ball like a big hamster ball?

I am looking into creating a virtual reality experience controlled by something like the VirtuSphere (  I know there are giant hamster balls out there, but they are inflatable so I don't think they would be strong enough for what I want to create.  Also, solid balls would be waaay too expensive (like the BuzzBall or a Zorb).  Ideas? 

Question by meztek   |  last reply

why my servo works on arduino and not pic microcontroller?

Hello, Iam trying to use servo to control the turning angel of RC car , my servo is feetech fs5113m . 1st i tried arduino , using a 5 volt supply voltage "1A" for the servo , which is lower than its actual required voltage , but it was still working perfect, i used the "sweep" in arduino examples just to test it. then i used my pic16f877a to run it , and i was facing a problem where the servo keep 'buzzing' and doesn't work until i give it a push , and i was using the same power supply , then i tried both 7 and 6 volts "0.8A". and nothing but "buzzing" here's the code : void servoRotate0() //0 Degree { unsigned int i; for(i=0;i<50;i++) { PORTB.F0 = 1; Delay_us(800); PORTB.F0 = 0; Delay_us(19200); } } void servoRotate90() //90 Degree { unsigned int i; for(i=0;i<50;i++) { PORTB.F0 = 1; Delay_us(1500); PORTB.F0 = 0; Delay_us(18500); } } void servoRotate180() //180 Degree { unsigned int i; for(i=0;i<50;i++) { PORTB.F0 = 1; Delay_us(2200); PORTB.F0 = 0; Delay_us(17800); } } void main() { TRISB = 0; // PORTB as Ouput Port do { servoRotate0(); //0 Degree Delay_ms(1000); servoRotate90(); //90 Degree Delay_ms(1000); servoRotate180(); //180 Degree delay_ms(1000); }while(1); } and its running on ISIS simulation , and its a code that i actually took from someone who tried it and worked , so help me with this please.

Question by omar emad   |  last reply

Why does my LED lamp have AC voltage from case to ground and is it dangerous?

Here's the deal:  3-section under-counter LED light strip in an aluminum housing, with a 2 wire AC cable and plug for 220v. I found however, that when I set a voltmeter to AC and measure between the case and a ground (water faucet, natural gas line or the ground from an electrical socket) I get 74 volts with one unit and 89 with another. The seller first pointed out that a grounded cable should be used. I replied with pictures showing the unit is built to accept only two wire and comes with a two wire cord. Then they said using a sink as ground didn't truly represent ground and that the measurement was faulty and that the current is not dangerous regardless.  I took additional measurements using an electrical ground and the metal pipe from the natural gas line. Same result. However, I'm having trouble measuring current. I put the probe into the ten amp side, set the meter to the mA/A position and got nothing, although I did hear a buzzing sound emanating from the lamp housing--that can't be good. I then put the probe into the mA socket and tried again.  Same buzzing, no reading.  My questions: 1. What's wrong with my setup that I see no current measurement.  2. Is this a dangerous lamp? I took the one near the sink down. The other one is not within reach of an accidental grounding, so it is up until I'm ready to return both units. -Bob

Topic by bobcov   |  last reply

Do you have the Arduino code for keypad, PIN (password), change/customize the PIN via the keypad and LCD?

Hello All, I've been researching this for a while but I still can't find anything to meet my requirements: - the setup is based on Arduino UNO - enter a PIN of 4 digits via keypad - have multiple PINs such as master, user 1, user 2 - show the digits (or *) entered on an LCD - give the user the option to change the PIN via the keypad by following a certain sequence such as entering 9999 or hold # pressed for 5 sec then entering current PIN  followed by the new PIN. Optional but it will make my life easier given that I am very new at Arduino coding: - turn on green LED for a set time when PIN is correct - turn on red LED for a set time when PIN is incorrect - buzz tone 1 for a set time for correct PIN - buzz tone 2 for a set time for correct PIN - make an I/O go high for a set time when PIN is correct (used to energize a relay via a transistor, etc.). I can probably figure out the basic things (mostly the optional stuff) but I would appreciate it if somebody shared with me some sample code that covers the requirements above. As you can imagine, I need this to build a PIN based security lock. Thanks for your help and I am looking forward to your answers. D.

Question by F22-Raptor   |  last reply

How can I make a cheap set of sound/light buzzers that you would use in a trivia quiz to know who buzzed first?

I want to make a set of quiz buzzers so that, for example: someone asks a trivia question and two other people have a button each, both connected to a sound and/or light buzzer. The question is asked and as soon as one person hits their button and makes their buzzer and/or light come on, the other person's button then does nothing until the other person's light and/or buzzer has turned off. (Basically, only one light can be on at any one time) I have searched various sites on how to build one of these, but they never tell you how to make it like the title of it says, they just have links on the site that let you buy their product. If anyone has any idea on how to make this work, then I would appreciate any ideas you have. Thanks for your time.

Question by Jareadx   |  last reply

How do it change a battery appliance to run off a wall plug when it has no built-in power pack outlet?

I have an alarm clock that runs on two AA batteries (I'm not fond of radio plug-ins they buzz too much). So that I can sleep easy and not worry about the batteries dyeing in the night, how can I hook it up to a 240v ac/dc power pack and what size pack would I need? (I have access to heaps of p.packs but I have v. little electronics experience. I have the idea but not the know-how!) thanks for the help

Question by Sera2005   |  last reply

Help with a diy acoustic guitar pickup

I am putting together an instructable for  playing rocksmith free on your pc  , with a small cost for people like me who dont have much money. Not having money means that : 1) the software must be free ( i found the solution to that)  2)i must make acoustic guitars compatible with the game (since i dont have an electric and i dont have the money to buy one)   I need a diy acoustic guitar pickup  to plug in my computer , with low budget and  clear sound no hums and buzzes ( this is the most important part) If anyone can help me  please pm me .  Thank for your time ,  Phevos

Question by phevtron   |  last reply

Making plasma in a vacuum chamber?

Im having trouble generating any kind of plasma and i guess not fully understanding this. Heres my setup: A metal pot with a Plexiglas lid as vacuum chamber. a pressure gauge on top A vacuum chamber A MOT as the power supply. Dont have equipment to measure high voltage but id guess around 2KVAC as thats what i understand is standard Two terminals about 2 inches apart inside of the chamber made from copper. one coming from the top, one from the bottom.  I hook up the terminals , hear the nice MOT buzz, but nothing happens inside of the chamber. The mot has been tested and does work.  Any clue or direction to point me in?

Question by GalaxyX   |  last reply

My kid broke his arm, is getting a cast tomorrow, should I try to add some LED's?

My 6 year old broke his arm on friday night, they can't do a fiberglass cast until tomorrow. I was thinking what if I prewired an ultra bright LED and ask them to wrap it into the cast with just the led poking out. I was thinking I could decorate his cast to look like Buzz Lightyear's arm with a "laser". The wire could come out the top that I could connect a battery pack to so he can turn it on and off. Is this a good idea or not too smart? I'm trying to think of ways to make my son feel a little better about having a cast for 8 weeks.

Topic by tonythemediaguy   |  last reply

[arduino] Computer PSU damaged my servos?

Hi guys! I was hoping You could help me with sort of a problem :( So I bought this Modecom 400W power supply and hooked up 2 servos to molex 5v line and ground. For control signal i used standard arduino uno "example" code. Servos were buzzing for a while but they did not react to commands. Did I need a power driver for the servos? I think they should draw as much current as they need from the line, shouldn't they? So beforehand, I connected the motors directly to arduino for power and they worked. Now - nothing ;/ Nothing inside looks damaged (I think) Anybody had similar problems? Arduino UNO R3 Tower Pro MG 996R

Topic by januszknur   |  last reply

Piezo buzzer for LED flasher? Answered

I have built the flasher found here; It works great with the LED turn signal bulbs on my bike I would like to hook up a piezo buzzer to the flasher that buzzes when either the right or left signal light is on (motorcycle flasher reminder buzzer). What would be the easiest way to do it? The flasher runs constantly when the key is on, only powering the turn signals when the turn switch is activated right or left. The buzzer won't work when hooked up to the B+ and load terminals like it was on the mechanical flasher with incandescent bulbs. I figure the problem is that the incandescent bulbs provided the ground for the buzzer though the filaments. Does this sound right? Thanks. Sorry about the long diatribe.

Question by pofarm   |  last reply

Microwave transformer electromagnet?

Hi so I was bored and decided to make an electromagnet out of a microwave transformer by taking the secondary off and keeping the primary. I hooked it up to some 9v batteries and stuff but it wasn't that strong so I researched it a bit and found out you can hook it up to the transformer input voltage (which was 240v AC) so I did but when I turned it on it made this very loud buzzing noise and I thought I saw what looked like flame in the socket. I turned it off imediately and unplugged everything. Whatever the magnet did must of been strong because it broke itself apart slightly. I tested the sockets with a multimeter and they still say 240v but I just want to make sure I didn't do anything bad to it. Also did anything actually go wrong or was this all meant to happen?

Question by jlandreth1   |  last reply

Help- My Printer is BLIND!

So here is the story- my grandma moved out of our house, and I got an older Windows 2000 computer. I also got a working (at the time) printer (jetprinter...HP...I think) and hooked it up in my room about a month later. The ink was low, so we spent ~30 dollars on new cartriges. So, even then, I hooked it up... hit print, and buzz click whirr...just like it should...and bloop: load paper is displayed on the screen. But had paper..a bunch! So I took it out, restartyed the computer, turned off (and then on) the printer seperately, and tried to print agian. No worky. Supposedly the printer is still out of paper, even though it is sitting right there! Is it blind?!?!?!Any help would be appreciated. It is a good printer (or was), and the ink in it alone is new and worth $30!

Topic by John Smith   |  last reply

I basically need a person detector. Sort of...

Some friends and I have been playing laser tag a lot recently, We try to team up in Free For All but always end up shooting each other due to darkness. I was wondering, is there any way (Cheap) To build something that each person can have, one person has a device that sends a signal to the other person when about 20 feet away, and on the other persons device, it would vibrate or buzz or something to indicate that the other person is coming. So basically when one person is 20 feet away, all other devices vibrate. One sender, and the rest receivers. And they would have to be pocket sized. Is there any way of doing this? My original plan was to use ElectroMagnetic Fields, one person has the detector, and the other, an EM Pump, But I could not find a pump design powerful enough for 20 foot range. Please Help! Thanks.

Question by Tuckoguy   |  last reply

Advice for a buzzer element

Hello I am developing a small device which requires  a sound alarming. The idea of the device is to be attached to your phone for example and if you wonder where your phone is, the device will turn on the sound alarming in order to give you information for its location. So, I am searching for a buzzer element which: - consumes up to 3.6 V; - is small (diameter up to 20 - 25 mm) and thin of course; I decided to use a buzzer element similar to this one but I am not sure if it will do the job. I am concerned about something else, I have a buzzer at home which produces sound of high frequency and when you close your eyes it is absolutely impossible to find out where the sound comes from. Can somebody help me, please? Thanks a lot!!!

Topic by paveltashev   |  last reply


So as you can see in the video at the end of both songs I am having a issue with it cutting/shorting out. All i can think of is the tip31 transistors im using are overheating maybe? but what is really wierd is it shorts back to the speakers?? I have one transistor driving the blue leds and one driving the red leds. the red leds are being powered by a 9v supply and the blue is 15v( dont remember the MA but they both provide plenty. They are wall warts. When i  plug in the 9v power supply it makes a high pitch buzzing noise.... If anyone has any pinters i would appreciate it. Thinking of adding more transistors.... I cant figure out how to link it so just copy paste the link below into your browser...; and i'm following this diagram cause it does not have a switch like the others.

Question by ARGMISTER   |  last reply

Arduino knock sensor with a twist

Hey there! I live in a dorm and there's no preinstalled doorbell so i thought i'd do something funkier. I've used the stock Arduino Knock code and modified it a bit so agitating the piezo will make a connected buzzer beep. The problem is that while the entire setup is working, the buzzer itself is very very quiet. With a pure tone making script the buzzer will make a loud BEEEP, but combined with the knock code it's extremely quiet. I'm new to Arduino's so please bear with me when i show my code (most is copy/paste to fit): /* Knock Sensor      This sketch reads a piezo element to detect a knocking sound.    It reads an analog pin and compares the result to a set threshold.    If the result is greater than the threshold, it writes    "knock" to the serial port, and toggles the LED on pin 13.      The circuit:     * + connection of the piezo attached to analog in 0     * - connection of the piezo attached to ground     * 1-megohm resistor attached from analog in 0 to ground       created 25 Mar 2007    by David Cuartielles    modified 30 Jun 2009    by Tom Igoe  */   // these constants won't change: int speakerPin = 9; int ledpin = 13; const int ledPin = 12;      // led connected to digital pin 13 const int knockSensor = 1;  // the piezo is connected to analog pin 0 const int threshold = 10;  // threshold value to decide when the detected sound is a knock or not // these variables will change: int sensorReading = 0;      // variable to store the value read from the sensor pin int ledState = LOW;         // variable used to store the last LED status, to toggle the light void setup() {  pinMode(ledPin, OUTPUT); // declare the ledPin as as OUTPUT } void loop() {   // read the sensor and store it in the variable sensorReading:   sensorReading = analogRead(knockSensor);        // if the sensor reading is greater than the threshold:   if (sensorReading >= threshold) {     // toggle the status of the ledPin:     ledState = !ledState;       // update the LED pin itself:            digitalWrite(ledPin, ledState);     buzz(9, 2500, 500); // buzz the buzzer on pin 4 at 2500Hz for 1000 milliseconds   delay(100);    }     // delay to avoid overloading the serial port buffer } void buzz(int targetPin, long frequency, long length) {   long delayValue = 1000000/frequency/2; // calculate the delay value between transitions   //// 1 second's worth of microseconds, divided by the frequency, then split in half since   //// there are two phases to each cycle   long numCycles = frequency * length/ 1000; // calculate the number of cycles for proper timing   //// multiply frequency, which is really cycles per second, by the number of seconds to   //// get the total number of cycles to produce  for (long i=0; i < numCycles; i++){ // for the calculated length of time...     digitalWrite(targetPin,HIGH); // write the buzzer pin high to push out the diaphram     delayMicroseconds(delayValue); // wait for the calculated delay value     digitalWrite(targetPin,LOW); // write the buzzer pin low to pull back the diaphram     delayMicroseconds(delayValue); // wait againf or the calculated delay value   } } If i get this working i'll see if i can make an instructable out of it (and make a "secret knock identifier"). I ended up using this code: [url][/url] which works (code can be found by following the links) And it works! I'm still wondering what was wrong with my (pasted) code though.

Topic by Eirinn 

How to choose speaker for DIY iPhone speaker system Answered

Hi guys I'm a bit of a tinkerer, but new to audio.  I'm designing an ipod speaker dock from a Gigaware 40-303.  Got the thing apart, but the left speaker is making a bad buzzing sound.  I want to replace the speaker, but I'm unsure of what to look for.  The specs for the system I got the circuit from are as follows: output: 15 W x 2 Driver size: 3.0" x 2 signal to noise: greater than or equal to 65 dB freq response: 80Hz-20KHz rated load impedence: 4 ohms power rating: 100-240V -50/6-hz, 1 amp So I need to look for a 3" 15 watt 4 ohm speaker?  I don't want to underload the circuit and draw too much power.   What about range?  Mid, tweeter etc?  Does that matter? The original speaker is pictured below.  The sticker on the back is the only identifying info.  Thanks for any help you can provide.

Question by DirtMcGurt   |  last reply

How to power a 5v circuit with batteries? And will my circuit always draw power?

I'm building a fridge door sensor that will beep when the door is opened. The one that is on my fridge right now is very inaccurate and so I want to improve it. So what I've done is make a sensor that is mounted onto the door to makes a contact when its closed. When it's opened, I'm using an ATtiny 25 to wait 30 seconds and then make a pulsating buzzing noise through a buzzer. The ATtiny operates in a range of 2.7 - 5.5v and I want to power it with batteries. I'm new to electronics so I don't know much about powering stuff with batteries. My questions are: How do I get that power that I need? Will the batteries get drained quickly because of the circuit design? (power always going through the contacts) Also: Does anyone know exactly how to hook up a battery to an ATtiny? I think that the positive should go through my switches and then into vcc, but I'm not sure where to put the negative. Thank you so much!

Question by yohiyoyo   |  last reply

can some help me pemanantly fix my speaker system?

I have this surround sound speakers i made my self and they are great but when they break i cant even listen to music. i can usually fix them my self but they never stay fixed and they just broke again. so i have tons of speakers all differant kinds and they all have differant color wire which makes connecting them difficult. they have work just fine (while working) but now the rear channel has no sound also the second set of speakers have a buzz( like on a guitar amp) when so sound is playing through can someone please help me with this ok so we have all realized that ive blown my left channell amp on the second speaker but what about the first? if you look at the diagram one is connected to the other i have tried to put just 1 speaker to the first amp but no sound comes out (the speaker has been tested and its not blown)  why is this and can i get another speaker to work with it

Question by fastcar123   |  last reply

Quiz Buzzer Lockout System help needed

Hi all. my church has task us youth to design a quiz buzzer lockout system type of thing to be used for a bible quiz. so the host will ask a question and 8 people will try to be fist to press their button... the fastest button will lockout out all 7 other buttons so they wont buzz... after he answered then the host will press a reset switch and continue with the next question... i did a ton of research and always end up with arduino arduino arduino... and the instructions is all for 4 or so people and its not very clear to understand or easy to do. i know a bit of programming so that wont be a challenge. i love electronics so that wont be a problem. i just need a clear set of instructions to follow and some guidelines and parts to buy... (im 14 years old... )  the quiz is end of march. it for 8 people cause 8 youths of 8 different churches will compete.  if anyone could give me a plan or guide or point me in the right direction that would be super !!! i know im gonna need some wire... allot of wire... and an arduino... thanks in advance to all you wise folk :) oh btw i live in cape town...

Topic by moppyking   |  last reply