Is This circut right?

I need to know if circut for a 9v usb charger is right. I didn't have the usb port at the time. Any help?

Topic by Dread_Neck 8 years ago  |  last reply 8 years ago


Sound Circuts?

I was wondering if anyone had any simple sound circuts with variable pitch? It doesn't have to be very fancy just beeps and boops ( beeps and boops are preffered actually) Ii just need something that can create sounds with variable pitch and of any length

Question by Articas 8 years ago  |  last reply 8 years ago


Trouble with Electric Circut

I am trying to make a proofing box for bread making, and have run into a small snag. When I try to adjust the electricity going to the light bulbs in the box with my dimmer switch nothing happens, also when I try to turn the light bulbs off with the rheostat it trips my circuit breaker. I am using 4 7watt 120volt bulbs arranger in a parallel circuit, which are connected to a 600watt dimmer switch. If anyone knows what I am doing wrong I would appreciate the help.

Topic by Sedgewick17 10 years ago  |  last reply 10 years ago


led selection circut

I am building a 500 DVD library shelf.  I'd like to be able to select a number, on maybe a keypad etc, and have just one led turn on on one location of one of the shelves, indicting the location of that DVD.  As usual and understandable, I would like said system to be as inexpensive as possible.  I'd like to run it off of a battery.  I can do it with three selection switches and an individual set of wires to each LED.. Just seems like some IC would work if I knew a little more, and maybe reduce some of the wiring.  Like maybe an IC under each shelf that could select which led on that shelf to turn on.  I intend to drill small holes into the face of the shelves and insert each led about 5/8" apart with the wiring run back through and then under each shelf.  Lots of tiny wires and lots of LEDs but if I could make it inexpensive enough it would not only help in finding a movie to watch but it would aid in putting it away later.  Since to some extent, each DVD is variable in size, the location of any DVD is a little dynamic, but any one LED should be close enough to guide me. If you don't have time to fill in all the knowledge I am missing, any place that you can point me would be appreciated... It seems to me like it may take a number of IC to make several selection to power up just one LED>   thanks Dave

Topic by oneofsharp 7 years ago  |  last reply 7 years ago


When it comes to noises near your circut breaker, listen to your children.

Well the other day I was at home and my parents were at work. I was hearing some weird noises from around our circut breaker. So I called my dad and told him I was hearing noises and it sound electrical. He didn't believe me until last night until I told him there were more noises comeing from it. So he opened the little door and flipped one of the switch thingies back and forth and it was arcing! So we replaced it and there was this weird blue purpley powder on it. So if your children hear noises around your circut breaker, you might want to check it. My mom said she heard something coming from over there but she thought it was a mouse or rat outside or in the wall. (Our neighbor has rats and they come over to our house all the time)

Topic by Sunbanks 11 years ago  |  last reply 11 years ago


Protector Circuit?

How can I make a circuit that will protect an LED when I plug it into a traditional light bulb plug?  hint- homemade LED light bulbs.  

Topic by Buzzsushi 8 years ago  |  last reply 8 years ago


How do I use a negative voltage regulator?

I have some 7905C voltage regulators, and I'm wondering if I can use them the same way I would use a 7805 voltage regulator except on the opposite side of the circuit.

Question by misterpicture 7 years ago  |  last reply 7 years ago


Could I have some help coming up with a circuit that turns it self off after three momentary button presses?

Hi, I was wondering if I could have some help coming up with a circuit,  Basically me and my friend are modding nerf guns and I thought it would be cool If I could find a way to make the rapid strike fire three darts then stop (or three round bursts XD) Any how the part of the dart gun this in-tales seems to be the little arm that pushes darts into two rotating discs (this is one that uses fly wheels as opposed to a plunger) it works on a motor and gear that pushes it in and out, pushing the trigger activates this.  (I thought it would be a solenoid and that the trigger would put out electricity in bursts, or are those called pulses? any way that's where all this using a momentary switch idea comes from) So if anyone thinks that they can make a circuit using only the power from the trigger and lots of good timing a lesson would be much appreciated :D My Idea seems unnecessarily complicated but it's all I could come up with :D ,Any way the idea for the momentary switch circuit would be put some form of proximity sensor switch near the arm (the one that pushes the dart into the fly wheels). Something like a magnet switch or IR thingy ( I forgot what there called I think magnetic reed switch and Infa red proximity sensor or detector?) the idea after that was that each time the arm passed the sensor it would activate the sensor,  using that and the trigger(if they were both needed to initiate the circuit then releasing the trigger would reset the circuit) the first and second shots would push the dart into the fly wheels and the third would also push a dart into the fly wheel and turn off the circuit(or turn on the circuit activating a spdt relay and switching the link to the motor off) So far I've come up with some ideas using relays but just pressing the button once activated the whole circuit, I've also though of using a capacitor but I don't really know how to use them, if they work by holding X charge that can be filled by pressing a momentary button, that is hooked up to Y amount of power (possibly through a resistor), Z amount of times fills the capacitor stopping the circuit that would work,  though I would have to find a way to discharge it... Thanks for any help if I get any XD , and if posting my current not working circuit designs would help I'll do that, just have to figure out how to draw a circuit...

Question by justomeguy 5 years ago  |  last reply 5 years ago


120 volt flasher circut

I need some help finding a way to flash a 120 volt incandescent light bulb. Im looking for a way and have found close to nothing. if any one can help, thank you

Topic by newwarhammer2 7 years ago  |  last reply 7 years ago


Reducing voltage in a circut for the layman.

I understand something, but for some reason I am unable to use that knowledge in application to find another answer. Let's say I am building something: (This setup is completely imagingary, so I will use strange numbers.) I have a battery box that has 4 AA batteries rated at 1.5V and 2.7amps (according to wikipedia).   Now lets say I want to hook that up to a LED that has a max 4 volt 20mA forward. I know that I need a resister. I know that V = IR. What I can't wrap my head around is this: How do I change that equation so that is tells me how many Ohms resistor do I need? Because according to that equation if I increase the resistance, I increase the voltage. Becuase were talking about the same source. Do I need to use two V=IR equations and solve for one then place that value in the original.   I just can't get it....maybe I have had too many beers since graduating, or using algeba? I need a layman's way of understanding this...(exasperated sigh...)?

Question by Asmodean_7 9 years ago  |  last reply 5 years ago


need help finishing circut

I need to turn 3v into 6v with out messing with the frequency and to figure out what capacitor to use (this is for wireless power transfer). any other advice or comments on possible mistakes I may have made. all help appreciated

Topic by tykora 4 years ago


hi i am looking for a good free pc circut designer what should i use?

I cant find a good one im designing and making a custom 2 channel sound controlled light

Question by masterchrisx3 8 years ago  |  last reply 8 years ago


why does one bulb keep on blowing, while others on the same circut dont? Answered

I have a alarm system at home that turns on a 12v circut when the alarm is active.  Attached to this I have 3 12v globes (the kind you find in old car indicator lights connected in parallel.  The one globe keeps on blowing.  Each bulb lasts about 3 days (this would total to about 40hrs total on time tops. The other two lights never give me any issues.  Any hints on what to look for?

Question by Lylec 9 years ago  |  last reply 9 years ago


Can I use USB to power a Relay??

I have purchased a simple 4 channel relay (http://www.fort777.co.za/index.php?main_page=product_info&cPath;=800_801_946&products;_id=10357&zenid;=fvokss9s9ucgakrrn9ged441hs1oushq) My Aim is to use the USB port on my TV to control the relay.  The intention is to have it switch on a lamp when the TV is powered up.  I have run into an issue and being a bit of an electronics novice I am not sure what to do.  The Relay kit as both a 12v input (I assume that is to actually power the relay coil) as well as a connector that has pins for Ground, 5v and Signal for each relay (S1 - S4). If I attach the red wire from USB (5v) to S1, and the ground from the USB Cable (Black) to ground, the indicator LED flickers and then dies.  at no point does the relay click, and the light seems unaffected whether the 12v power is connected or not.   I feel I might be missing something simple, but as an utter novice in this area I am not sure.  Any help. 

Question by Lylec 5 years ago  |  last reply 1 year ago


how do i know which is better ?

I want to build a automated hidden ipad stand drawer for the dash of my car and i cannot find any good plans or tutorials on the internet can anyone help ?

Question by paddy. 6 years ago  |  last reply 6 years ago


Anyone Have experience with Adafruit Square FSR?

I am hoping to create a circuit that will variably control the speed of a motor through pressure. If I were to wire up one of these http://www.adafruit.com/products/1075 , simply as the switch between a small motor and a power source around 5v, would it work to simply turn the motor off at rest and vary the speed with pressure? Is there a way to use this resistor as a "switch" without using an Arduino or  other micro controller? Any help is appreciated. Thanks! 

Topic by Flashflint 4 years ago  |  last reply 4 years ago


How do I use a relay?

I have never used a relay before, and I don't know a lot about them. I think I might need one but i'm not sure exactly how it works. From what i understand, when electricity is passed through one set of pins, another set of puns allows a charge to be passed through, like an electricity powered switch. I might be completely wrong, and if anyone could help that would be great.

Question by tim127 6 years ago  |  last reply 6 years ago


Is it possible add mA to solar cells in series/parallel circut if you don't use the same number of cells in each circut?

I had in mind 3 circuts running in parallel with one at 4x2v(8v total at peak), and two other circuts running only one cell each, 2v. The mA of each single cell is at 40mA. Would this circut setup make it 120mA? It would be nice to solar power my airsoft rifle's 6xAA 600mAh(3000mAh total) battery pack in less than 30 hours with only a diode in the circut...

Question by ethereal haze 10 years ago  |  last reply 10 years ago


How to make an oscilating relay circut? Answered

Can anybody tell me in detail, how you would go about making a relay oscilate? Please explain and give directions.

Question by tesla man 6 years ago  |  last reply 6 years ago


remote control LEDs?

I need a circut to be able to remote control 2 LEDs and the reciving circut must be very light. Any ideas where I can get such a set of circut boards? Schematics? Plese help!

Question by techturtle2 8 years ago  |  last reply 7 years ago


How much does a camera flash circut boost voltage?

I want to know how much a standard flash camera circut boosts voltage. I'm trying to build a railgun and I simply wish to know about how much it does, as I cannot afford a multimeter or voltage meter. Information welcome.

Question by StartedBullet 7 years ago  |  last reply 7 years ago


I need a circut board done- and I can't get it to work at home and I'm to cheap to fab them will someone do it?

I need a circut board done- and I can't get it to work at home and I'm to cheap to fab them will someone do it?

Question by 16zzundel5 9 years ago  |  last reply 9 years ago


Can somone help me figure out this binary counter?

I don't remeber exactly what it's called but i have no idea how to use this and I sorta want to, can anyone help? (man im tired and bad with words) http://pdf1.alldatasheet.com/datasheet-pdf/view/50663/FAIRCHILD/74VHC4040N.html

Question by justomeguy 4 years ago  |  last reply 4 years ago


What is the easiest way to recharge a capacitor? Answered

I'm in need of a way to recharge a capacitor ( or more ). The disposable cameras circut is trashed ( it didn't work even before then w/ the right setup ), and I can't afford another. Is there some way to avoid the circut in favor of a more direct route? I need to recharge it for use as a shocker or coil gun, and have an AA battery holder as my power source as well as a switch to fire. Please help.

Question by StartedBullet 7 years ago  |  last reply 7 years ago


Anyone know of a resistor that is sensitve to sound vibrations?

Does anybody know of something like a photo cell, except instead of the light being the variable to determine the resistance of a circut, it would be sound and vibrations? If ya do, could ya give me a comment on what it would be called, what they're used in, and where ya could maybe buy one? Thanks! -xD

Question by ! xD ! 9 years ago  |  last reply 9 years ago


how do I hook photoflash capacitors in a series circut?

I am trying to build a larger coilgun with more volts, but am having truble hooking the 120uf 330v photoflash capacitors in a series circut. they don't charge, and when charged seperatly and connected in series, they just discharge eachother, leaving no power left.

Question by the mechanical engineer 9 years ago  |  last reply 9 years ago


is there a simple way to create a tone with a DC circut?

I want to create a simple electronic instrument that plays a tone when a button is pressed. I have no idea how to make a tone or what components are needed. thanks in advance for any advise p.s. this being powered by a battery is preferred

Question by FastLearner 7 years ago


what use is a super capacitor?

Question by halolord 8 years ago  |  last reply 6 years ago


Any one can tell me is this circute working or not?? Please Urgent Expert advice equired? Answered

I want to make this 1.5 to 10volt inverter, I tried but it didn't worked. So I want advice from expert in this that is that circute working or not? If not what changes should make it work? Here is the link to schematic http://dangerousprototypes.com/2011/03/04/1-5-to-10-volt-inverter/ Thank you in advance.

Question by njrajgelani 6 years ago  |  last reply 6 years ago


Nichrome wire rope cutter

I've recently started working on a nichrome wire rope cutter. I've built a prototype that uses 2 9V batteries that connect in parallel to a 2" piece of 24 AWG nichrome wire. It works, but burns through the batteries within a minute of running them before they don't output enough current to heat up the wire.  I would like to improve this by turning it into something that is much less likely to burn itself down, or electrocute me in the process. I've been looking into ac to dc converters so I don't burn (almost literately) through 9V batteries. I'm kind of a bit hung up on the electrical engineering portion of this however. If I were to use something like a 12V 5A power supply, and then nearly short it with the nichrome (a resistance of .2477 OHMs) is the adapter limited to 5A, or would something start to melt. I have a feeling I need another resistor in there to reduce the current (if I but a larger PS), and or a potentiometer to dial in the temperature.  Any help would be appreciated.

Topic by halolord01 3 years ago  |  last reply 3 years ago


two in one: How to work with transistors and how to use a 24v system in a car and a 12v? Answered

1: So I have been playing with transistors, awesome little woks of science aren't they!?  Well everything I have done has been arduino based with the same voltage switching as the transistor's input.  Now of course there has to be a way to send more voltage across than is used to do the switching, but how do you add a ground and prevent that high voltage from entering the controlling circuit.  The basic idea is using an arduino to operate a transistor which controls a 12v DC light source.  Lets assume the arduino can't handle 12 volts and can only get up to 5v which is the highest supplied voltage.  Can a simple resistor attached to the emitter side work? I still feel like the voltage potential on the emitter would be too high for this to work, but I am new to transistors, any wiring diagram recommendations.  I have been through amplifier diagrams, but its too confusing to pick out just what is going on with the transistor, and the most important factor of why. 2: I was looking at aircraft lamps today for the sake of improved vehicle lighting, its quite popular around here, but the majority are 24 volts, at least they are on the brighter end of the spectrum.  Now I know you could use two 12 volt batteries and get the 24 volts and also just pull isolated power from one, (i think) to run the 12v system.  The problem I see is when applying voltage from a 24 volt alternator, It could potentially bring the 12v system voltage above desired levels right?  There isn't a high power easy 12v limiter is there either.  So would these require two completely separate systems along with 3 batteries or are there other ways of handling this task which allude me. Bonus: for all those light lovers check out these incandescent beasts!: http://www.normanlamps.com/index.php/cPath/473_53 Oh no, now I realized these are PS type, there goes those radical fun ideas.  Would this mean probe start or pulse start, and if so how do they work?

Question by jj.inc 5 years ago  |  last reply 5 years ago


Best cheap non camera circut for coil gun charger circuit?

Im building a new coil gun this time without camera flash circuits so best cheap alternative preferable with the schematic. Thank you  

Question by rocket_man 7 years ago  |  last reply 7 years ago


Anyone have battery charger monitoring circut plans?

As we all know the biggest problem with cordless power tools is the battery life.  One of the biggest reasons for battery failier is because the companies sell the tools with cheap chargers that cook the batteries.  The tools I have use 18v nicad batteries.  The chargers are the type that take about 3-4 hours to recharge a drained battery pack.  Does anyone know where I could find plans for an inexpensive circut that I could retrofit into the battery chargers to keep them from cooking the batteries?  Idealy a circut that would detect when the battery is almost fully charged and drop down from the 'fast charge' to a 'trickle charge' and eventually shut off completely when the battery is 100% charged. Be a super nice extra bonus if I could put in a circut that monitored the batteries while in storage, maybe topping them off once a week when I go a while without using them.

Question by etcmn 7 years ago  |  last reply 7 years ago


Using Capacitors in a flip flop LED flasher circut?

Hello guys, I am very new to electronics, so please bear with me. I am trying to build using specs from various places a seemingly simple flip-flop led flasher using a 9V dc power source, a pair of NPN transistors, a pair of capacitors, a resistors. Now I have built the circut several times on my breadboard. I have yet to get the circut to work. I tried to troubleshoot the problem myself, and done a little research. It seems that capacitors wont work with a dc current, or so most of the web sites say. The problem is all of the circuts I have seen use capacitors, even the 555 circuits. The only thing I have done different from the diagrams is I am using a slightly larger (30 or so farads) cap. They are the the ceramic disc type. Am I using the wrong caps? Not sure what I am doing wrong?

Question by Asmodean_7 8 years ago  |  last reply 8 years ago


How to isolate a battery pack from a controlled short?

so i am trying to make a portable electric stove and am trying to isolate the heat coil from the battery pack itself i know there is a way of doing this however for the life of me i cant remember how it works or what it is called. any help would be greatly appreciated! [edit] so there was some confusion on what i am trying to accomplish. i keep burning up batteries (when i say burning up i pretty much mean just that.) they don't like being connected to circuit that's sole purpose is to short out (albeit in a controlled way.) i wanted to isolate the batteries from the part of the circuit that is shorting to create the heat. if that still doesn't make sense or you think my problem might be something else entirely, please let me know. also so you know what my circuit looks like. it is a battery box power supply soldered to my heat element as well as a variable resistor to allow me to change heat output. hopefully that helps clarify.

Question by siege10 8 years ago  |  last reply 8 years ago


Fixing a old tv that shorts out?

So i have this old Magnavox projection tv, hasent been run in a long time due to a shorting issue between a heatsink and something (its been so long that i dont even remember) I can plug it in and find excatly where its shorting but i dont want to fry the tv... I do remember that it is one of the heatsinks by the flyback that it arced from. I also have the basic wiring diagram for the tv, but it only shows how to adjust the picture, what connects to what and, what wire is what. Should i try and turn it on again and find where its shorting and possably fix it, or just call some tv repair guy who knows more of what hes doing.

Question by knexsuperbuilderfreak 5 years ago  |  last reply 5 years ago


what is the best soldering iron for small projects? Answered

For like circuts and stuff

Question by moomooman 9 years ago  |  last reply 9 years ago


how do you wire led's in a line circut with one on off switch. very new to this.?

I want to make a sign for a play that can be turned off for other scenes. I want to wire led's together in one circuit with one power source. (how much power and what type would I need?)

Question by bluefly1215 10 years ago  |  last reply 10 years ago


What's Wrong? Electric Bass Feedback

I own a Ibanez Ergodyne EDA 900. When ever I touch the 3rd string (D string) Tuning knob, bridge, any metal touching it, I get feedback sounds to my amp. What's wrong with it. It's not the amp because I tested it with my friends bass. *** I Still don't know what happed but after i took it apart and checked all the conections (nothing wrong) I blasted all the dust out of it and IT WORKED FINE.

Question by maxxxem 9 years ago  |  last reply 9 years ago


Some new stuff i got

So recently my dad wanted to throw away a old tv we had that had a bad cord (yeah we could of easily replaced the cord but be have enough tv's..) and i remember seeing plasmana's plasma speaker a while back and that it used a flyback transformer, so i ripped the tv apart taking the pcb with everything on it, speaker, and the coil thingy on the tube, since it was the first time i took one apart i had cliped the magnet wire winding so thats almost no good so i just got rid of that, and then i took apart 3 other monitors i have gotten over the years, one had a set of speakers inside it, and that was interesting to use. and a while back my friend gave me a old 5cd/radio stereo, i would of just kept it using it for the 5 disc changer mostly but the door was broken, and didnt move well at all, so i scraped it and used the speakers. Oh and theres a PSU in there i ripped apart a while ago, i have another but its stored away currently. Anywho heres just a view of what i got, any ideas on what i should make out of all this?

Topic by knexsuperbuilderfreak 5 years ago  |  last reply 5 years ago


When building a capacitor bank, is it necessary to have a charging circut? Answered

So, I am going to build a capacitor bank in parallel, only a few regular caps from cameras, how would I go about charging these? Do I have to use the circut or can I just hook the battery to the bank for a bit?

Question by Speedmite 8 years ago  |  last reply 8 years ago


Trying to build a Alternator/generator welder?

Ok im trying to build a Alternator/Generator welder. i want it to be able to do Stick, Mig, and Tig. So other words three different circuts on one board. so i can switch between the three. 1. how should i control current: in between the battery and field post or after from the positive post from the alternator? 2. how to control the voltage: same as number 1 between the batt and field or from the batt post on the alternator? Also i understand the consant current constant voltage thing. that will be provided on the three circuts. Right now im just working on the stick welder circut ill ask about the mig and tig circuts later or you can pm if you have any info on them. im just trying to piece this togeather step by step. Any help will be great. and yes i know this is a very big project, and will require alot oof time to do.

Question by dmm1542003 6 years ago  |  last reply 3 years ago


How do I build a Circut to create temperature changes in LEDs? Looking for a range of 3000 to 6,000 for photography?

I see commercial lights for photography that can change color in the range of 3-6,000 or tungsten to daylight values. These are not arrays of three RGB lights but rather single LEDs and the combination create fairly substantial light sources.  Looking for a schematic for some sort of regulator.  Thanks Nathan nathan@cityviewmag.com

Question by NathanS126 3 years ago  |  last reply 3 years ago


Could i use an ignition coil and breaker points to fire a coil gun?

I've made one of the basic models i've seen around here, but i was wondering if i could skip most of the painstaking soldering that i suck at, and use car parts. I'd still be soldering here and there, but not tiny camera circut boards. I'm not retarded, i am aware of the high volts at work on spark plugs, so spare me me the "you'll shoot your eye out" type lectures, already tasted that flavor. But would the automotive coil even charge if it is shorted across by the barrel coil? i know breaker type ignitions dont fire till the power source is cut by opening the breaker. but a spark plug is an open circut and i'm not sure if a coil pack will charge if that circut is closed.

Question by dubbio 10 years ago  |  last reply 9 years ago



Would a disposable FujiFilm camera's capacitor be lethal? The capacitor has no markings. Answered

I want to make a shocker, and after reading something here I'm considering just leaving the capacitor out of the camera charging circut for safety. The capacitor has writing giving away the ratings on it, and I simply need to know that I won't kill my buddy with it. Oh yes, and would the charge of an AA battery ran through the circut be enough to shock someone?

Question by StartedBullet 7 years ago  |  last reply 7 years ago


Will someone make me 2 PCBs??

I need two circut boards done and i have copper clad and PDFs and i can't get Mine to turn out right. How much would you charge me?

Question by 16zzundel5 9 years ago  |  last reply 9 years ago


What causes a front blinker on a car to blink fast when the rear blinker globe blows?

Why does the front blinker blink fast when the back blinker globe blows.Is it somthing to do with the load of the circut.

Question by legend4930 5 years ago  |  last reply 5 years ago


Help! I`m creating a cnc plasma cutter and wondering if annyone can help me?

I need a bluprint for the circut board to control 2 stepper motors an a relay. You can contact me on torarbr@live.no. Sorry if my englis is bad.

Question by torarbr 10 years ago  |  last reply 8 years ago


Microwave Transformer To EMP

Hello, my question is simple. If I connect about 3v to a microwave transformer and then to a coil, would it make a efficient EMP wave (shutoff a calculator). I know that I can use a disposable camera, I just am learning different ways to do it. (Sorry for the pic, done with my phone haha)

Topic by Skydazz 2 years ago  |  last reply 2 years ago