Volts and current ? Answered

I'm confused what's the difference between voltage and current ? also what's the difference if I power a 1.5v motor with 3 1.5 battery's in parallel and same motor in 3 1.5 battery's in series

Asked by Robinson ruiz 9 years ago  |  last reply 9 years ago


Limiting current?

Good day, I am interested in an effective way of limiting current for a TEC application. This application involves using the TEC's (12V @ 1A) to reduce the incoming air temperature in a noise isolating enclosure from ambient temp to about  5-10 deg C cooler. In doing some research on implementing the TEC's I have found that these units operate at their greatest efficiency around 1/3 of max amp input and lower when you do not have a large heat load to "pump" away. So all of this being said I would like to operate a number of TEC's at  this low amperage range, and to be able to cap their maximum current draw between .1 and .3 amp.  Any input would be greatly appreciated, thanks

Asked by MatthewSternbauer 2 years ago  |  last reply 2 years ago


Current Artwork

I am doing this for a friend's wedding. The medium is acrylic paints. The photo is fuzzy and doesn't do it justice. You can't see the skin tone changes and highlights, :( This is my first time painting something like this, it's all mainly guess work (The hair, the skin, etc.) Work in progress. What are you working on?

Posted by Spl1nt3rC3ll 11 years ago  |  last reply 9 years ago


how to decrease current??

I have 12volt 8.5amps battery with me i want the output of 12v & 4amp  i dont knw how plz anyone suggest me

Asked by SrinidhiS5 1 year ago  |  last reply 1 year ago


What is an Alternating current? Answered

It is always easy to understand the working of Direct current, but I need to know about Alternating current right from the basics till advance. I would be grateful if you could help me understand about Alternating current better.

Asked by DeeptiR3 1 year ago  |  last reply 1 year ago


how to reduce current ?

We designed a circuit . But it is drawing 70mA of current. I want tot reduce it for atleast 30-40mA.

Asked by SunnyJ1 3 years ago  |  last reply 3 years ago


Current in IC chip

Hello, It's a bit stupid to ask (I think), but essential to me. From all schematic I readed over intructables I never saw anything or anybody that cared for that. If a IC have a maximum and minimum current to respect ie: 6mA to 10mA, do we even care? Do I need to limit the current somehow? As I said, every schematic I readed never added any resistor or talked about anything relate to limiting the current on the VCC for the integrated circuit. I'm currently building a device that use one 555 timer IC in astable and a few others IC and they are all connected in parralel to the power suply. Thanks

Posted by sxdemon 8 years ago  |  last reply 2 years ago


High Current measurement

I need to measure Current from a welding machine to make a alarm if it goes down below some level for ensuring better quality of welding. The current normally set is of the order of 200A max with around 100V DC.Not sure if i could use some clamp-on meters and pass those values out to Arduino for switching circuit. Shunt resistors may be a better option. But to make a signal conditioner to convert the ma output will be a problem i guess..is there something i can do with Arduino.. any ideas guys....? Thanks in advance Chuppandi

Posted by chuppandi 6 years ago


Transformer current restriction? Answered

I am aware mostly how transformers (AC - AC) work, but I am lest informed on a few key parts.  I know there is a direct relationship between windings and voltage as well as an inverse relationship between voltage and amperage. The thing I don't understand is what limits the current produced by the transformer.  I know you can keep droping the secondary windings to increase amperage, but eventually you get to a point you can no longer do that.  To overcome this one can use three sets of windings wired in parallel which will retain voltage but increase amperage.  The amount of amperage is still limited to the maximum throughput of the primary, but how do you actually find this out.  If one wanted to make a variable current AC welder, it would be relatively easy to predict the voltage, but establishing a potential amperage is more difficult.  What actually establishes the maximum output of a transformer because in some cases the max current is reached long before the actual failure, and is there a way to predict the end product.  P.S. I am not looking for the answer they use voltage/current limiting circuts ect...  I am looking at something like a pole pig which maxes out output before internal failure and contains no additional circutry, not a wall wart

Asked by jj.inc 4 years ago  |  last reply 4 years ago


Specific output of current? Answered

I'm getting a little more knowledge about current measured in mA, but it's still all confusing. From my understanding, your project draws the current needed out of your battery. If my LED uses 25 mA, then the LED will be sucking 25 mA from the battery. If I have two LEDs, then it would be sucking 50mA from the battery, thus reducing its life. So, based on that, how can wall warts have a specific output of amps? How can a wall wart put out 1000 mA? If you use a project that only takes 700mA what happens to the other 300 mA? What if your project use 1,500 mA? And. . . How do you measure the current being pulled through a basic circuit and your average 555 circuit? Thanks,  

Asked by HavocRC 6 years ago  |  last reply 6 years ago


Diode current ratings Answered

How can I determine the current rating of a diode  A forward current of 2 amps is needed and the reverse voltage is 12v                                                                hopefully   Gordon                                                                                                   Thank you

Asked by GordonT3 3 years ago  |  last reply 3 years ago


Varialbe current regulator?

Have you ever seen a variable current regulator? i googled it but i keep getting standard voltage regulators Any help would be appreciated!

Posted by Sandisk1duo 10 years ago  |  last reply 10 years ago


BLACKROD's Current K'nexWorkshop

I thought some of you K'nex people might find this fun to look at. I just finished the Cyclone. Currently I'm putting on different rubber bands, as you can see in the picture. Enjoy.

Posted by BLACKROD 11 years ago


Current measurement with arduino

Hey I try to measure current with hall-sensor amploc 25A, it sense magnetic-fields, offset voltage is 2.5V and I use arduino uno. I get 519 value from analog pin and 37mV/A is hall sensor sensitivity. My formula is outputValue = ((((sensorValue*5000.0)/1023.0)-2500)/37 multimeter shows 0.112amps when I put load but I dont gett correct value on LCD Is my formula OK?

Posted by mattilaniko 3 years ago  |  last reply 3 years ago


Is it a current limiter or what???

when rebuilding a battery pack for a Sears cordless drill,I encountered a tiny diode or fuse or thermistor of sorts,in the wire coming from the negative pole.It appears this is only active during charging. At any rate,what is it and where do you find a new one??

Asked by 9 years ago  |  last reply 9 years ago


Reducing current to drill

Hey everyone. I'm building a potters wheel for my girlfriend for Christmas, and for the motor I'm using a corded drill. I want to use something like a sewing pedal to control the speed, rather than the trigger of the drill. I've looked it up (on here) and it sounds easy enough, but the problem is that most corded drills are 4 amps and over, and the highest amperage I've found on a sewing pedal is 1.5A, I'm assuming this would blow up the pedal. Is there some way I could use a resistor to reduce the current drawn by the drill? Would the drill still operate on 1/3 the current? It won't need even close to full power. Where would this resistor go? Thanks in advance.

Posted by checkmyusename 5 years ago  |  last reply 5 years ago


Too much current Answered

I built a hotwire device to cut foam insulation. If I connect it directly to a 12 volt battery, it gets 'way too hot very quickly--the hotwire turns red almost immediately. However, if I connect the device to a wall charger rated at 5 volt/2amps, it works fine,if a little too cool for a good cutting speed. What's happening here?

Asked by suncoaster 11 months ago  |  last reply 11 months ago


Current at Maker Faire

I'm sure you know that the Maker Faire is next weekend... and all of us at Current.com and Current TV are excited to share with you that we are going to be there! If you are going, please drop by our booth and introduce yourself (you can find us at booth #217-X). We'll have a very special DIY treat to share with you, and a full set of computers if you need a place to blog from (and for those of you interested in embarking in the wild world of vlogging, we'll have webcams too!) If you aren't going to the Maker Faire, then feel free to visit us at http://current.com/topics/32970052_maker_faire If there is something that you are just dying to learn more about or get a closer look at, we have a team of people on the ground with cameras in hand who can be your eyes and ears for you. Just email your questions on the above mentioned page, or email Leah at llamb@current.com. Videocan not parse options from: classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" width="400" height="400">, {width:425, height:350} And by all means, feel free to introduce you and your DIY blog by clipping your blog comments to the http://current.com/topics/32970052_maker_faire You make all sorts of things. We want to hear about it. PeaceAda

Posted by Ajala 10 years ago  |  last reply 10 years ago


Conventional current. A question about DC current flow. Answered

I just started reading electronics for dummies and it tells me that DC current flows from negative to positive.  It later states that in the early days of electronics it was assumed that current flowed from positive to negative.  Later they discovered that it flows from negative to positive.  Some schematics will have an arrow for current flow going from positive to negative (conventional flow).   Why do they still do this if they know the current flows from negative to positive?  This is confusing.  Thanks.

Asked by pennsteve 9 years ago  |  last reply 4 years ago


Limit DC current from LiPo battery?

Dear Colleagues,  could you please advise if there is a way to limit DC current from LiPo battery?  I need to push the high current (80A) through very low resistance circuit, but do not want to fry LiPo. So need to limit the current at 80A I am not an electronic professional, and all solutions coming to my mind are based on increasing resistance of circuit (by adding resistance manually, or constructing something like FET-regulated limiter). The problem here is that I will generate lots of heat, and need too much space for its dissipation.

Asked by SergeyD15 2 years ago  |  last reply 2 years ago


Ac current limiting per light bulb? Answered

Dear all.. Please help me to know: how wattage of light bulb(please see photo) is needed for limiting my circuit 120ac 60 watt maximum Thank you so much.

Asked by lam 5 years ago  |  last reply 5 years ago


How to increase AC current without using amplifiers and external power source? Answered

Iam having 12V AC and the current 100mA.When i apply the 12V AC to secondary winding of 5V transformer.The voltage gets boosted up to 64V.I don't want voltage to be boosted,instead i want to increase the AC current without using transistors,external power sources,etc.Like the transformer which is boosting voltage when applying AC voltage at secondary.I need to increase AC current only and not the voltage.I want these to be done without using amplifiers.Because amplifiers uses external power source.Any one tell me how to increase current.Otherwise is there any way to increase AC current by reducing the voltage?

Asked by Rajkumar2506 1 year ago  |  last reply 1 year ago


Electronics help

I need an easy way to distribute power 2 way and when the on button is switched the correct goes one way and when off then on again it goes another? Thanks

Asked by Camyo 3 years ago  |  last reply 3 years ago


i want online or software about circuit creator ...?

Asked by Rehmatullah 6 years ago  |  last reply 6 years ago


can I turn 2A into 5A? Answered

I am makinga hot wire foam cutter and using the hot wire foam calculator from Shawn James and it says that I need a supply of 7.5V 5A, but my transformer only gives 2 A. I've seen voltage multipliers and I don't know if there's a current multiplier. If so, please give me the instructions to make one.

Asked by tgferreira184 6 years ago  |  last reply 6 years ago


Low AC to DC conversion

Hi, I'm looking for simple way to convert a low AC into a usable DC, of say 4 - 5 volts for charging batteries. I recently saw one discussed online, specced at costing about a quarter, but couldn't find a way to do it, or a way to purchase something like that. Thanks!

Posted by fafnir665 11 years ago  |  last reply 7 years ago


Current Consumtion by a DC Motor?

 I am asking few questions EV related, more current related. Let a consider a dc motor rated 4hp at 24v and 2hp at 12v. So is there a way to calculate ampere draw of the motor at various loads.(like no load, full load, or any load). And if we know the full load current of the dc motor then can we calculate the max load for the dc motor. Next as the dc motor is 2hp at 12v then will this value be constant or will the motor be able to produce 4hp at 12v even rather than at 24v. And will a battery eg 50ah be able to supply more then 50amp.

Posted by flyingdutchmen1659 5 years ago  |  last reply 3 years ago


Current Free E-Books? Answered

Anyone know where I can download CURRENT free e-books? Current like Rick Riordan, James Dashner, etc.

Asked by schoonovermr 8 years ago  |  last reply 8 years ago


Arduino maximum current draw? Answered

What would the maximum current draw through an Arduino be? (ATMEGA328) - I'm planning on running 16 LEDs from it and I need to know if I should be powering them separately somehow.I have the appropriate resistors (100ohm and 180ohm LED dependent).

Asked by jonrb 5 years ago  |  last reply 5 years ago


Charging capacitors with different currents? Answered

How does charging a big capacitor with a high current affect it rather than a low current? Certainly time taken decreased. What are other effects, and is it as safe as using a low current?

Asked by ARJOON 7 years ago  |  last reply 7 years ago


current limiting for phone battery? Answered

I have a very old phone and its battery is outdated, I am replacing the battery with a new one but that is rated differently Phone ratings: 3.7V DC ; 350mA New battery rating: 3.7V DC ; 860mAh ; 3.2Wh >what is the difference in "mA" & "mAh"? >My main question is ; do I need to put some resistor in between the battery and phone input to limit the current or the current flow depends upon the load ?, do I need to put resistor in series b/w the phone and battery or in parallel. Try to provide a schematic to make answers more clear NOTE: I dont want to replace the phone and am working on it as a restoration project. Thanks in advance!

Asked by MYawar 5 years ago  |  last reply 5 years ago


reducing current on a power supply

So I am trying to reduce the on the current power supply I have from an old router. The out put is 12v DC 800mA (.8A). I want to use it to run a man 12v .3AI just wanted to make sure I did my math right and to make sure I didnt miss anything.Ohms LawI = V/RR= V/I V = 12 I = .812/.8 = 15 ohms resistance in theroy_Current on the fan is .3 A, I am assuming that is the max. So desired current is .25I = .25 V = 12 R is current resistance, X is additional resistance Q=(R+X)I = V/QQ= V/IR+X = V/IX = (V/I) - R V = 12 I = .25 R = 15(12/.25) - 15 = 33 ohm resistance neededSo I would need a minimum of 33 ohm resistor. Am I correct?Sorry for the explicitness of the math, its been drilled into me to show every step.

Posted by dragonkeeper117 9 years ago  |  last reply 9 years ago


Reduce current but maintain voltage?

Do resistors reduce voltage or amprage? It's amprage as far as i know. I've got a power supply thag outputs 9kV at 300mA and I need to get it to 9kV at 0.2mA, someone suggested a 450kOhm resistor. When I phoned go get one they asked if I want a quarter watt resistor, what does that mean (1/4, 1/2 watt). I need to reduce the current comingfrom the power supply because I'm using it to power a fusion reactor and the diodes I have to comvert the AC to DC can only handle 0.02mA

Asked by JunaidA44 2 years ago  |  last reply 2 years ago


how is ac current generated? Answered

Ok, so I was under the impression that brushless motors were AC motors (and therefore conducted AC current), until recent internet searches proved me wrong. I am curious how AC current is conducted, is it conducted using brushless motors? Or is it a different type of motor that will generate such electricity?

Asked by A-Nony-Mus 8 years ago  |  last reply 8 years ago


Wall outlet current draw

I have built a transformer, that will take 120v, and step it down to 2.5v. I used all the right parts, and the correct rated wire for this. My only issue, is that when i connect the primary coil, to a call outlet, at 120v, it draws more current then my 5A fuse can handle, and the power goes out in my home. I need to get 1.5 amps, @120v going through my primary coil, in order to get the desired output on the secondary. I was wondering, how things "draw" current from the wall, as well as if i where to use a resistor, wouldn't it still draw too much amperage, and just dissipate it in heat, to give the desired output (i cannot use, because it draws more than 5 amps). i could not find a resistor out their, that could handle over 100 watts, so i was also wondering how things like vacuum cleaners only draw a small amount of current. Would i need some sort of current regulator (if that's even a thing)? if you had a light-bulb, and a battery, would the circuit the light-bulb is attached to drain less current, if their was a resistor, and thus having the battery last longer, or would it draw the same amount, and just dissipate energy through the resistor in the form of heat, to give the light-bulb its self less current?

Posted by merlinj 3 years ago  |  last reply 3 years ago


constant current or constant voltage?

Hello, I'm looking into driving about five separate piezo ultrasonic water misters and one of them have the rough requirement of 24 volts. my question is if i wanted to drive all five at the same time I'm thinking I would want a 24 volt constant voltage source, is this accurate? Bonus question: what dictates whether a constant current or a constant voltage source is needed?

Asked by waldosan 1 year ago  |  last reply 1 year ago


Increasing current for hho cell?

What is the simplest method for someone like me who has very little experience in electronics and a low budget, to achieve a high current output for a hho cell? This is for a hho cell and torch so the voltage must be low and the current must be high. Basically what Im looking for is a cheap and easy way to create 3v -5v together with 10-100 amps. Are there any specific household appliances that can put out this current? Not car batteries, car battery chargers or wall sockets. Also is this enough to kill you or just give you a bad shock?

Asked by mitchells 8 years ago  |  last reply 7 years ago


How to pulse dc current? Answered

Hi! I was just wondering if people could give me some different ways to pulse dc current. I am trying to power a transformer with dc. Thank you in advanced.

Asked by tesla man 6 years ago  |  last reply 3 years ago


VFD voltage and current needed

I've a Futaba 4-LT-16 9L big VFD display. Unfortunately I'm not able to find the datasheet or exact details about it. Maybe I could contact Futaba... The only informations I found are these two schematics https://revspace.nl/old/IMG_2239.JPG (but it doesn't match with the 4-LT-16 display) https://revspace.nl/old/IMG_2240.JPG (not very useful to me) from this page and this video from the same page. Could someone help me? Are there typical voltage and current for the filament (I think it depends from the length and the display dimension)? What about the grid voltage? Thanks!

Asked by andrea biffi 5 years ago  |  last reply 4 weeks ago


Low Voltage Higher Current?

I am having a strange problem on a USB peripheral.... it is a digital radiography sensor that overheats. I believe it may be due to the power supply to the motherboard, but I don't know for sure. I am ASKING FOR YOUR HELP in reasoning out what may be the cause. Anyone with computer/electronics experience, PLEASE HELP!!! I was told that my power supply is too low voltage, and that current is going up in the USB peripheral causing it to heat up. I always thought V=IR means that if voltage drops so does current. But in other places I read that if voltage drops, current goes up so that the wattage/power usage stays the same according to P=VI. So which is it? V=IR or P=VI ? If my power supply has too low voltage, will the current in the device increase to compensate? Or will it just have a lower current? Does it depend on the circuit and the exact electronics in the USB peripheral? Here is my SETUP. It is SIMPLE: Antec AR-350 power supply connected to a motherboard Asus P5N7A-VM in an ATX case. All I have otherwise is a SATA hard drive and a SATA DVD-ROM in there. That's it! Problem started to happen about 1.5 years after I got the computer. That is why I am thinking maybe it is the power supply, or maybe it is the motherboard?  The computer works fine in every other way! It uses Windows XP and has a wireless keyboard/mouse which also works fine. BIOS settings screen Hardware Monitor shows voltage for USB 5v reading about 4.9v, within tolerance. However, one of my USB peripherals is a digital xray sensor. It works ok a few times, then it starts to overheat and fail. This only happens on this computer. When I use another computer (like a laptop) with the same USB hardware it functions ok and never overheats. I don't have any problems on the other computer, even thought I am using the same software/drivers. I bought a different ATX case with a new power supply, and just moved the motherboard, HD and DVD over. Now the motherboard BIOS shows under Hardware Monitor that it is getting 5.2 V instead of 5v, so it is higher! Also the 12 V is higher (around 12.2v) and same for the 3.3V. All the voltages are HIGHER! So I have yet to test this new configuration with the USB peripheral sensor.  Could the motherboard be faulty? I did notice the motherboard looks "curved" with the area under the CPU sort of bulging out. However, with this motherboard you will see there is a huge heat-sink/fan that gets clamped over the CPU and that may be bending the board. Keep in mind the board works perfectly otherwise, so I am wondering WHY it would only affect USB for this one peripheral and not for the keyboard and mouse? Maybe the circuitry on the keyboard/mouse is more tolerant to low voltage? Would appreciate your thoughts please.

Posted by edy 6 years ago  |  last reply 6 years ago


Measure current and voltage with arduino? Answered

How would I measure the voltage and current of this circuit with an arduino?

Asked by flybye22 8 years ago  |  last reply 6 years ago


What is a constant current source?

I had some questions: What is a constant current source? How does a constant current source work? Do i need a cc supply for an led or would a cv supply work? Thanks :)

Asked by qwerty156 7 years ago  |  last reply 7 years ago


Current challenges not visible on iPad

Until last week I was able to pull/view the current challenge on the home page (using my iPad).  Now it seems the only way I can view them is if I log onto my PC and click on "contests". Is there a way to view the current contests (that are still open) conveniently on my iPad?  Thanks!

Posted by kcli 6 years ago  |  last reply 6 years ago


Constant voltage AND constant current? Answered

Hi, smart people of the internet :) Is there a power supply or a converter that can be set on a specific voltage and current, and keep both constant at the same time? I looked at ebay converters like B3606, DPS5015, BST400 and the like. They all have constant voltage (CV) and constant current (CC) settings, but they can't do both at the same time. If for example the current being drawn is too high, the unit switches from CV to CC and drops the voltage as much as needed to keep the current constant. Is a simultaneous CC CV power supply even a thing? Thanks!

Asked by Morgantao 1 year ago  |  last reply 1 year ago


how to limit to current to led's? Answered

Hi all I have a diy led project.  My batteries are dying really fast, I did a litte bit a research and find out that my led are drawing alot of current from my 3 AA's I wire my 36 led's in a parallel fashion voltage supply 4.5v vf = 3.4 per each led If = 20 ma  currently Not running any resistor through the leds.  What is the best way to make the battery last longer or to limit the current that is being supply led's? thanks in advance!!!!!

Asked by incogn 8 years ago  |  last reply 8 years ago


Bridge rectifier max current

I have 12V 1,8A transformer and few 1N4007 diodes that should rectify only 1A. But if i connect them in Bridge configuration will current pass through 2 diodes at each cycle and be Safe to use Up to 2A?

Asked by AnotherD1 8 months ago  |  last reply 8 months ago


What is the current of an ignition coil?

I need to know the amount of milliamp s of a basic ignition coil ?   (not an oil burner ignition coil)

Asked by The MadScientist 7 years ago  |  last reply 9 months ago


What's the current supply of a USB? Answered

I want put 3 LED's and a flashdrive into another container, and have the LED's turn on when plugged in, but I'm not sure how to go about wiring up the LED's. What's the supply current that I should use to find the right resistor? If a poorly made diagram gives you a better idea of what I'm talking about you're in luck! http://i317.photobucket.com/albums/mm395/applesnack/LEDdia.jpg I know USB gives 5 volts, but I don't know about the current. And would any problems arise from three LED's and the drive plugged into one USB?

Asked by applesnacks 8 years ago  |  last reply 8 years ago


Current Address for Instructables HQ?

I am going to be in San Francisco on July 15th and 16th, and I am planning on visiting the offices of Instructables. I keep searching for a street address of the office, but there are three different ones. Could I get the current address, the hours it is open, and who is likely to be there? I would love to meet the guys behind one of my favorite websites!

Posted by arpoky 5 years ago  |  last reply 5 years ago


What is the current output of a capacitor?

I want to make a circuit where a light is powered by a capacitor until it is discharged, and then powered by a battery until the capacitor is full again.  How long is it possible to power a light on a capacitor?

Asked by kaboom! 7 years ago  |  last reply 7 years ago