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 2 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 10 months 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 8 months 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 1 year 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 4 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 5 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 10 years 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 2 years 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 11 months ago



how to make a current meter with microcontrollel PIC 16f877?

I want to make a current meter with microcontroller and LCD 16x2 as display. what components do i need? and what is CT?

Asked by starda 7 years ago


how to make current meter with PIC 16f877?

please help, if anyone knows. tell me what components do i need to make current sensor? and the process to be displayed on LCD 16x2

Asked by starda 7 years ago



Voltage regulator? Answered

Does a voltage regulator IC (e.g 7805, LM317 etc) still draw current when there is no load?

Asked by .Unknown. 7 years ago


What is the current on my foam cutter? Should I be worried?

I built the 5 min. foam factory, but instead of a model train transformer ($45 for the cheapest one they had) I used a regular 12 volt transformer and a rectifier bridge (I had to borrow it from my infinite LED tunnel :'( ) Now when I went to buy a variable resistor/potentiometer for the thing my local electronics shop guy said that the 12 volt transformer put out too much current for the ones he had. Now this has me worried. How much current is currently going through this thing? Should I be worried?

Asked by shyguy567 9 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


Please help! How do I lower the current strength (Amps) in a parallel circuit so I don't fry my LEDs? Answered

I have a AC/DC adapter that gives out 4.5V and 500mA, how could I lower the strength of the current so that I can connect four LEDs (4.5V, 20mA) in parallel and not fry them? Sorry if I ask the impossible, I'm a total electric beginner. Thank you in advance!

Asked by dark_boshkarin 8 years ago


how to amplify a dc power of 7v and 130mA to maximum?

I know that i could do that using transistors, but how , what type and what rating of components should i use? should i supply transistors a separate current in order to power it? if i have to supply, is it profitable even after giving that current? Becuz we are wasting a power to increase another power!!

Asked by SRI HARIH 3 years ago


inrush current make mcb trip

Hi all, i have a problem with my miter saw, it run at 220v and have power 1.8Kw or 1800w my house power can provide 2200Va, the problem is, when i start the miter saw the MCB will trip,  so i must turn off all my electrical home aquipment , than i can use my miter saw. i try to search on g**gle and find that it need some slow start, or soft start so the mcb will not trip again. it cause from inrush current, when the motor start. but the slow start  some forum in indonesia say it can be done by using capacitor bank. to repair the power factor but there is no explanation what size of capacitor bank we can use for any diffrent load...especially a big load like mitter saw for sure, how can i reduce inrush current from the miter saw? what should i do?

Posted by beatobe 6 years ago


USB Power(ed)

I'm obsessed with USB powered gadgets, but i'm not sure what the USB current limitations are, I know that the power output is about 5v,  but i dont know if i can attach gadgets that uses less or more voltaje, so I was wondering if anyone here can give a piece of advice about what can or cant I do with usb power.

Posted by patotec 6 years ago


Procedure to getting Voltage and current of an LED without knowing ANYTHING else?

Good day good people. I got batches upon batches of various surface mount and dip leds. Not a single god damn seller wrote the specs on neither the website, nor the package and there are so many that I can't tell which one's from who. Regardless, however the ridiculously low price you get these things for, you can't really complain. So I need to know if there is a procedure to finding out the current and voltage of an led and that is without knowing a single rating about it. It it guesswork or is there a proper testing procedure? It can be a 1,5v can be a 2.5 or a 3v led I don't know. What should be tested first, what should be second? All I have is a basic multi-meter and besides checking batteries voltage I have't been using it for anything else. Thank you, folks.

Asked by MilesT9 1 year ago


What is the output current (limit) of a typical USB car charger???? Answered

I need to power 2 hard disks in the field. Power requirement: 900 mA each. For the 5V connection, I want to convert the 12V power input with one or more car USB chargers. I need to know if one or more chargers in parallel (how many??) are needed. I have sufficient 12 V juice (small lead acid battery). Additional: for surges in power consumption, do I need to add a capacitor? What would be the rating? Do I have to wire it in series or across? (Sorry I'm a layman in electronics...)

Asked by BobS 8 years ago


servos run on 6.5V, but how many amps?

I have five servos running off a picaxe sd21 servo controller and it will operate using four AA batteries, but I want it to run off a wall adaptor. Now theres plenty of adjustable adaptors on the market giving from 3V to 12V and I've seen one that might work for me that can be set to 6.5/ 7.5V, but does anyone know the suitable current range for my device.

Posted by jonnymelon 4 years ago


DC power drop alarm Answered

I need a very simple way to see if power is ever lost to load.  I am trying to run a long term test of at least 60 days.  I have a UPS that is powering a load and I need to be able to determine if the 12 - 15 V dc that the UPS is providing is ever lost. The UPS has a battery that will supply power if the AC input is lost.  The solution can be very simple and I really don't want the load to be reconnected if the current going to the load is ever lost. I need to know if the load is ever not powered, even for a brief instant.  I was hoping there might be some type of switch that would open if the current stopped flowing through it.  Sorry for the simplicity but I know very little about electronics.  Thanks for any help or advice.

Asked by brentatespicorpdotcom 2 years ago


Fan needs 12 volts at .44 amps. How can I limit the current to .44 amps from 2 amps, without losing the 12 volts? Answered

I am trying to power a fan that needs 12 volts at 440 milliamps. I have a wall-wart transformer that is 12 volts, 2.0 amps, and I many components. I have thermal compound,  heat sinks, resistors, 12 volt and lm317 voltage regulators. So, how can I limit the current to 440 milliamps from 2.0 amps, without losing the 12 volts? Also, I tried a resistor at 33 ohms and it burnt out. Thank you, Jeremy (Please note: I am teaching myself electrical engineering, I have not taken physics yet. My knowledge is based on sever books, web resources, and hundreds upon hundreds of youtube videos)

Asked by JBronen 5 years ago


What is the max input current for the lm317? Answered

I am having trouble understanding the datasheet. Is there a max input current for the lm317? If so, what is it? I want to supply 4A input current to it from a laptop power supply. http://www.fairchildsemi.com/ds/LM/LM317.pdf Thanks.

Asked by Dmxspider 6 years ago


0. What is Current ? 1. What is Voltage? 2.What is Frequency?

My Dout is : 0. What is Current ? 1. What is Voltage? 2.What is Frequency? I know Definition. But i need practical example for this thing OK. So what is my dout is 1. When voltage increased current is also increased !      But in some case When voltage increased current decreased OR voltage decreased current increased. How it is possible Current is depend on voltage so When Voltage is zero then current is also zero only know For Example: When 100 Watt bulb receive high voltage then high electron will flow through tungsten of bulb then bulb will give high brightness ok Then same 100 Watt bulb receive low voltage then low amount of electron only flow through the bulb then bulb give low brightness This is the Rule or Nature So Current is depend on voltage only. Then how voltage decreased when current increased. This is my basic dout not only this and many dout about frequency also And Thank U for Replying ME. Thank U

Asked by Xzyamaha 6 years ago


How to choose wire gauge for Brushless DC motor?

I'm planning to build a Brushless DC motor, with inrunner perm mag rotor and stator on the outside. How can i determine the proper copper wire gauge for the stator windings? How much current will the motor pull? At first i thought it was just "Power = Voltage * current", so knowing the power and the voltage i should be able to figure the current. However, when the motor is spinning it generates back EMF, which counters the applied voltage and diminishes the current. At no load, the motor should draw no current for an ideal motor, and only a small current in real life to overcome friction and losses. In any case it would be much lower than the nominal current. So, for instance, a 1000w motor at 50v should draw 20A nominal, but in most situations it would be less than that? How much is the starting current, when you have to overcome inertia/tire friction? I know the motor can take higher currents for small amounts of time, before it gets too hot,but how can i determine what will be the "average" current. Is there a rule of thumb that motor designers use?  Also, the amp rating for each AWG seems to vary a lot. Some places list a conservative rating that is used for home wiring. But other places list much higher currents. If the stator is on the outer side and exposed to air, how much current can the copper handle for each AWG? Any insight will be appreciated, thanks.

Asked by SlickT 1 year ago


Drawing current from a laptop computer... USB port? Answered

So here's what i want to be doing. I want to be able to draw current from my laptop's USB port, and control how much and for how long. Something on the lines of hitting keys on the keyboard to be able to turn on a wired device and turn it off, not like a charger which is always on.

Asked by themanwhosoldthe_world 7 years ago


How to reduce current without reducing voltage

Hi, I'm working on a sign that basically has LEDs as letters. I have 140 LEDs that I'm planning to put in series of 4 each and then 35 in parallel. My problem is that I was mailed a transformer that outputs DC 12v 1.25 A (Actually 12.3V 1.4A). The current is too large for what I need for the LEDs and I don't want them to burn out too quickly so how would I drop the current without affecting the voltage? Any advice would be appreciated, thank you!

Posted by ytan10 4 years ago


Can I Limit Current Without Dropping The Voltage?

This kind of a noob question. I have a power source that supply 12V, 500mA. And the device I'm powering takes 12V, 140mA. How can I drop just the current (from 500mA to 140mA) without dropping the voltage? Since using a resistor would cause the voltage to drop as well. (Right?) Any help is greatly appreciated. Thanks.

Posted by gyromild 10 years ago


how to make a 240v 2A dc power supply?

I need a 240v dc power supply for a project but my pablum is ,i need to reduce the current up to 2 amps i know how to reduce the voltage but how i can reduce current ?

Asked by vina1991 1 year ago


Nst transformer?

How do I find out how much current my transformer can drive? How do I compare the drive of my transformer, and what's the purpose?

Asked by wiccakingkamui 4 years ago


12 volt stabilizer/regulator (high current)

Hi, I need something that's able to regulate the car voltage that vary from 10.2 to 14.7 (with lower voltages at startup that's not relevant)  to a stable 12v with a tolerance of 1-2% at high current (need at least 35A but I don't want to full load it too often then 40A would be better). I saw something like a lm317 with some external transistor that's able to put out something like 15A but it required a 30V input and it was a too much low current. can you link me an image of a circuit that's able to do what I want?

Posted by andry08 1 year ago


how to limit dc current at 80A? Answered

Dear Sir,               I have a 48V 100Ah Lead Acid battery pack from which I have to power a electric drive train. I want to limit the current drawn from the battery to 80A & also short-circuit protection feature. Ipreferred MCB for this purpose but it  dint work out well. So I need an alternative for MCB, on searching over the internet I found that DC current limiter may do the job in my condition &. I am newbie in this field. Please guide me through the circuitry which may help me out. Best Regards, Rohit Patel.

Asked by rohit1491 2 years ago


modifying a mobile charger?

Hello, i have an old 2000mAh phone charger which i played with, it was supplying 3.5V.. i removed the battery and replaced it with 4 18650 batteries rated at 3000mAh each.. all are connected in parallel.. will this give me in theory 12000mAh battery? also, is it dangerous to use it or do i need to add any current limiter resistors to reduce the current..

Asked by AbdullahF2 2 years ago


How do i convert 12vdc 16A to 12vdc 5A using resistor ?

I want to convert the 16A current into 5A how can i do it

Asked by iudyoga 6 months ago


What happens when you induce two currents of differing wavelength on the same line? Answered

If I induce two currents of differing wavelengths on a single conductive body, say an iron pipe for example, how can I calculate what the resulting signals wavelength will be? Is it as simple as taking the root mean square of the frequency of the signals? Any ideas for calculating the voltage of the final signal? ------------------------------------------------------------------------------------------------------------------------- Example: Signal 1: 60hz at 100v Signal 2: 75hz at 100v RMS frequency sqrt(((60^2)+(75^2))/2) =  67.9153 ------------------------------------------------------------------------------------------------------------------------- Thanks  a bunch!

Asked by paulcauchon 7 years ago


How to generate a fixed differential voltage dependant on a voltage relative to ground?

What methods can I use to generate an accurate & precise variable differential voltage that's dependant on the output of a +-10V DAC? I tried to use a resistor with a small variable current sink using the classic opamp+NPN design, but no design I made would sink current below 1V. I need it to continue sinking current down to 0V, I do have a negative supply rail avalible. (I think my last question was a bit TL;DR for some, so this is a shortened version of that.)

Asked by -max- 2 years ago


What can I put in series/parellal with an LED to stop it from turning on at lower currents?

I have an application in which I want an LED to turn on when it sees 12 V and above 3mA?

Asked by neworison 9 years ago


Circuit analysis: I just wanna know, how can I get (Vx) in the attached circuit below?

Please pay attention for the current and voltage direction

Asked by Inventor Oreiby 3 years ago


confused about LED drivers and current

Confused about LED drivers and current. http://www.parts-express.com/pedocs/manuals/073-048-parts-express-manual-7169.pdf thats the driver im using and i want to have 6 1 watt LEDs attached to it. I finally found a 30volt power supply but it puts out 1 amp. from what i understand i cant put that much current through the driver. i was reading around though and it looks like maybe the driver is only going to pull what it needs from that amp. I dont want to blow my driver and i dont want to blow the LED. i would probably just try it out anyway but am still waiting for the parts to come in the mail...

Asked by RexHex 5 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


What is a normal current draw for an arduino ATMega168 with nothing connected? Answered

I'm building a handheld geiger counter using an ATMega168 microcontroller with the arduino bootloader. I was planning on using a 9v battery with a 7805 to power the circuit since the geiger counter power supply only draws 3ma and I did not think an arduino would draw much current. however, after building it on protoboard I found that the total current draw on the battery was in the neighborhood of 170ma and drained a fresh 9v in a few minutes flat. The rest of the circuit continues to work without the arduino, and draws only 20ma when the micro has been removed. is it normal for an ATMega168 or 328 to draw 150ma when loaded with a minimal program and none of its I/O pins are sinking/sourcing any current? It is possible this chip has been mistreated somewhat, would it being slightly damaged cause it to use more power than usual? maybe using sleep mode aggressively in my code to save power would work? also, does anyone know of a 5v regulator chip like the 7805 that does not use so much current? the 7805 burns up about 10ma by itself which is not so great when the geiger counter itself uses only a few ma.

Asked by hivoltage 7 years ago


Best resistor to lower my current?

Hi everyone, I recently started to get into electronics and now need some assistance. I have a 12v and I believe 1A of power. The component I'm connecting is 3.7v with a 450ma battery that uses 3W. I using a l78m05cp, I built what should be a 5v .5A psu, but I must have calculated something wrong because fried my component. I believe the current is what I'm not getting right. Using P=IV, I found I should be using .8A, but I really am not sure about it. Please help, I'll go broke if I keep frying things!

Posted by ramirez_armando 4 years ago


how to make solar diy cell?

How to make siliconcell solar power?

Asked by tayzar 8 years ago


How to select transistor?

Hi guys! How do you know which version of transistor to select when it comes to doing some projects? I mean, lets say i have all the parameters of my project, the output current and voltage, so how do you know which specific model of transistor to select from the data you have? Is there some kind of list from which we can select the required model from our data? For example, i have an LED array which draws about 90mA of current in total and has a total operating voltage of 15V, and from past instructables that i read on this site, i know that BC547 has a current rating of 100mA and can tolerate the voltages, so i can use it. My question is, that suppose i didn't read these instructables, then how will i know which transistor or FET i have to select that has a current rating of about 100mA and can tolerate the voltages(i.e how will i know that i can select the BC547 or alternative)? Also, when selecting a diode for example, i know from reading few instructables that 1n4007 has a rating of about 1A and can tolerate good amount of voltages. Suppose i don't know about the diode, then how will i know that based on my requirements, i can select the 1n4007 diode? This is an example in general, and it applies to all cases of load currents and voltages, and other semiconductor devices.

Posted by charmquark 5 years ago


Which transistor for ne555 output?

I have a simple circuit based on an ne555, the power supply is 15 volt provided by a robust ac adapter. On the pin 3 of the ne555 i need a max current of 4000mA. I was thinking to use a BD439 transistor, would be ok? And about the base resistor? Would be ok a 100k resistor or i need a different value? thanks a lot.

Asked by akopelumenuscu 2 years ago


why do we receive AC power in our homes if mostly everything converts it to DC?

*except lightbulbs and welders. maybe water heaters?

Asked by k_man93 8 years ago