Battery power

I have a battery powered laser on top of a spinning disc. This laser runs out of battery fairly quickly, I need to make it last longer somehow. Could I wire the laser to multiple batteries to make it last longer? If i manage to find a mains powered laser then it spinning constantly wouldn't work as it would have a wire. I ideally need to find a way to power this laser (probably 2 lasers) for most of a day with something that fits on a fairly small spinning disc. Any ideas? Cheers

Topic by happysnail   |  last reply


battery

Extensive knowledge on VRLA , AGM, MOTIVE POWER batteries. 1 to 24 cell batteries. 6,12,24,36,48 volts. Up to 2000 amp hr. The bonus here is I work with gentleman who has the worlds fastest street legal electric car. Videoinvalid movie: , {width:425, height:350}Videoinvalid movie: http://www.plasmaboyracing.com/videos.phphttp://www.plasmaboyracing.com/

Topic by ihovia   |  last reply


Battery Powered Lightbulb

Is it possible to power a household size incandescent lightbulb with a battery? If so how?

Question by DELETED_MakerNinja   |  last reply


Battery Powered Lamp

I have to make a battery powered lamp for a school project but having no experience or knowledge whatsoever in electronics I really need help! I'm using a halogen GU10 bulb which is 35W, 240V, toggle switch and 2 AA batteries. Can someone please explain how I would wire the light bulb to a toggle switch and batteries? Also, do I need a resistor anywhere? Apparentely halogen bulbs aren't really suitable for lamps, so should I change to a superbright LED? Thanks!

Topic by jemily   |  last reply


Solar - Powered Batteries

Check out these cool batteries! Their creator is Knut Karlsen.See what he said:At home i always have some batteries lying around, either rechargeable or normal ones. Usually they are empty, but i'd like them to be always fully charged. I could use a normal charger and there is a lot of solar devices that charge rechargeable batteries. I wanted it simpler; why hasn't anyone made a battery with integrated solar cells? The idea of the "SunCat" batteries where born. The batteries should just bask in the sun like a cat and left for a while, in a sunny window, they would slowly recharge.For more details visit this site.Thanks!Stanislav

Topic by comodore   |  last reply


Solar power & battery? Answered

Hi everyone, I would like like to power a circuit that requires 6v from a battery charged by a solar cell. Could someone recommend a battery & cell specs? Would like the circuit to run at night for at least 3 hours. Battery needs to be quite small. I've picked Powerfilm solar cells, just need to know what voltage & amperage to use for a small 6v rechargeable battery. Thanks! 

Question by BlondeJamesDean   |  last reply


7v from 12v?

I need to run a 7v / 1.6 A DC water pump and a 12v / 1.13 A DC fan from a small portable battery pack. If I use maybe 8 "D" cell bateries, do I need a converter to power the 7v pump or will it work with 12v? Thank you,

Question by fastrack777   |  last reply


Converting mains power to battery power?

I have plans on building an electric go cart, however, the only motor I currently have is mains powered, as such I was wondering if anyone knew of any ways to convert mains powers to battery power, hopefully car batteries as these would be what I using. I've searched high and low and can't seem to find anyone that has done this, let alone a tutorial. Anyone with any idea's or links would be very helpful. Thanks in advance.

Question by ads100   |  last reply


battery backup

I have a really cool sunstech weather station but when the power goes off it loses time date and weather prediction. I live in Spain and we are prone to daily power cuts. I need a low power 5v back up system to power it. Any ideas welcome

Topic by malchall   |  last reply


power pack for battery powered mp3?

I am wondering if its easily possible to convert a mp3 that runs on AAA to mains via a power pack, which we all seem to have plenty of laying around. i realise that the AAA battery is 1.5v or there abouts while the closest spare power pack i have is 4.0v dc / 350mA will it work, or is it possible to further step down so it would be suitable ? via electonics - or do i need to find a powerpack that matchs a AAA battery voltage. i was going to wire this to the battery terminals ... or am i just looking for trouble? lol

Question by agatornz   |  last reply


Battery power and power consumption help!

I have a geocache project and need help with the power supply and power consumptin inside it. The basics of the project: It is a large wooden box. The box has a on/off switch. It also has various various coin slots. Flip the switch, turning it on, to supply power to the solenoid inside. Dropping a coin through the correct slot will trigger a momentary micro switch which activates the solenoid and springs out the drawer of treasures. Take your loot. Close the drawer. Turn off the switch and leave it for the next adventurer. And it works! Yay! Commoonents the question:  The solenoid is a 12v  door latch solenoid. https://www.adafruit.com/products/1512 The battery is a 12v 5ah sealed lead acid battery.  The coin micro switch is: https://www.adafruit.com/products/820 My question. This geocache that lives, protected, about 3 blocks from my house. I obviously won't be charging the 12v battery very often. Since this setup only has momentary power draw once in a while. Say once a week. Maaaaaaybe. Does anyone have any alternate power recommendations? I am okay with changing out the batteries once in a while. But I'm hoping for a once every few months. I originally used a new lead acid battery but it seems to have died. Possibly from letting the charge fall to low and then sulfation occured. I'm considering using a 11.1V Lipo Rc battery instead so I can recharge it at various levels of depletion. Thing is I need it to last a worth while amount of time without loosing power but also killling the battery from just sitting there.  Thoughs woukd be GREATLY appreciated.  -McG

Question by McgCache   |  last reply


Power phone on the battery with usb power?

Hi! I plan to make my old phone as a wifi booster. The only problem is that the USB "hole"/socket is borken. So I came up with a solution: I added + and - from a usb cable and then placed it on the phones battery. Should I worry if it touches the middle thing of the battery? I mean that thing between + and - . I think it won't if I place it carefully in the phone. I will connect the USB cable from my PC as I don't want to do it with strong power from the power point. So should I worry with the USB power from the pc  if something goes wrong?. [b] Should I go with this or not?..[/b] I hope you understand I wrote this very fast, I can re-write if you don't understand thanks!.

Topic by Davve95   |  last reply


Battery Powered Computer Lights

I have this item left over from my computer modding days. A set of cathode lights, there is two small rods, which connect to a main box, which then plugs into molex connecter for power. What i need help with, is can i hook this up to a battery, and if yes, how do i go about it? I have some experience of soldering. So i shouldn't be too lost. Thanks in advance. Gmj,

Topic by gmjhowe   |  last reply


laptop battery? Answered

I have a dell laptop which does not seem to charge when I try to charge it with the power lead. At the bottom of my screen it says 'plugged in, not charging'. What can I do to make it to charge? The power supply always overheats and gets in my way.

Question by knektek   |  last reply


Paper Batteries

Has anyone read anything about the up and coming Paper (thin) batteries ? Paper Batteries: A paper battery is a flexible, ultra-thin energy storage and production device formed by combining carbon nanotubes with a conventional sheet of cellulose-based paper.A paper battery acts as both a high-energy battery and supercapacitor, combining two components that are separate in traditional electronics. This combination allows the battery to provide both long-term, steady power production and bursts of energy. Non-toxic, flexible paper batteries have the potential to power the next generation of electronics, medical devices and hybrid vehicles, allowing for radical new designs and medical technologies.What do you think? Will it replace these monsters one day?

Topic by Goodhart   |  last reply


Battery recommendation

Hello, I'm looking for a rechargeable battery for a project and I'm not having any luck finding a suitable one.  Here's what I need: The battery will need to be between 12 - 18v with between 1-2 amp.  This will be powering a set of speakers, so not really sure what type of amp hours I need.  The battery will need to fit into a tin lunch box.   An idea I had was to use a 12 or 18v battery for Power Tools - not sure if it will work though.  I also found this, http://www.altex.com/12V-Lithium-Ion-Rechargeable-Battery-Set-LBP-124500-P150057.aspx not sure if it is powerful enough though. Any thoughts/ideas is appreciated.  

Topic by RabidNoodle   |  last reply


Option GlobeSurfer 3?

Ok so I have a wireless cellular modem/router here is the link to it http://www.option.com/en/products/products/wireless-routers/globesurfer3/ I would really like to power it from battery and im pretty sure i could just get a battery pack from radio shack or something and the correct dc adapter tip but i want to be sure is there anyone who could assist me in this

Question by anthony2201   |  last reply


Power my boombox

I have this power supply from a device that is not needed anymore. I have 2 of them (so i can harvest the other battery for another project, or to help run this one).. It is a backup battery unit designed to power my old device even if the power in the house goes out. I have some questions about the compatibility with a project i am working on. I'm sure it's obvious to most of you, but i labeled the parts in one pic so that i could pinpoint my question. A. is the battery terminal clips B. the feed of power to the device not being used anymore C. the plug that recharges the battery So then logically D is the board that feeds power from the battery, and E is the recharging unit. The pic isn't great, but there are 2 ribbons that attach D to E. I can also provide better pics if something isn't clear enough. My question is this... I am building a semi-small boombox with a car audio head unit. Since a car battery provides 12v, and the battery in this unit provides 12v, can i use this contraption to power my project? Can i simply cut off the adapter on the end of B, expose some copper, and attach to the power of the head unit? It seems simple to me, but my knowledge of electricity is VERY limited and i don't want to burn down my house or ruin my head unit. So far, i haven't paid a penny for anything and i want to keep it that way.

Topic by jjiont   |  last reply


Powering an LED strip? Answered

Hi, I am looking to use a small LED strip on my bicycle. Something like the product below. I have no experience with LED strips, and am looking for a way to power them. I want something small & light to mount somewhere on my bike, and wondered what the best options would be? Would a 12V battery pack be suitable (see below). How long would this last roughly? Thanks! Dan LED: http://www.ebay.co.uk/itm/2x-6LED-Eagle-eye-Super-Bright-White-Flexible-Car-Daytime-Running-Light/151040285688?_trksid=p2047675.m2109&_trkparms=aid%3D555003%26algo%3DPW.CAT%26ao%3D2%26asc%3D29%26meid%3D1853554389978170290%26pid%3D100010%26prg%3D1013%26rk%3D2%26rkt%3D15%26sd%3D271286250637%26 Battery pack: http://www.ultraleds.co.uk/12v-1-25a-15w-mini-power-supply-ac-dc.html

Question by skatmandu2002   |  last reply


Wind battery charger and heat up a copper wire?

Is it possible to heat up copper wire with a small wind turbine and also charge a battery at the same time please help thanks dean 

Question by Deano1247   |  last reply


Wireless Power?

OK so recently I have noticed that almost any sort of power can be converted into a different type, sorta. Anyways, it takes power to create radio waves or any wireless wave. Would it be possible to just send out plain radio waves and get something to pick them up and convert them into usable power? Now I know the farther you were from the source, the weaker the power would get, so you might have too send out a fair voltage signal to get some good range. Also, would it interrupt any electronics in range or anything like that? I was just thinking about this and wondering if it is even possible to get actual wireless power around your house or something without using batteries or interrupting anything in your house. Thanks.

Question by noobererer   |  last reply


USB power? Answered

I have a 1.2 V nimh battery and a 3.7V li ion (no protection circuitry) battery, which would add up to 4.9V if put in series. However, I want to turn it into a temporary USB power supply (5V) so ignoring all the things regarding putting 2 batteries of different capacities together, is there a way to kick the voltage up a tiny bit? I was thinking something like filtering the output of a joule thief, possibly. I also have a solar panel (4.5V, ???A) and was wondering if that could help, but I don't want to rely on it too much.

Question by .Unknown.   |  last reply


battery powered light bulbs?

Will a 12 v battery power a 12 v bulb (23A alkaline batteries, 6S6?12V - 6 Watt bulb), and for how long? Also same question w/a (6 Volt - 5.0 Amps - S8 Bulb, Alkaline Battery 6V A544 4LR44 PX28A battery)?

Question by MichelleH160   |  last reply


Battery Powering an Rpi3 and Monitor?

So I have plans to assemble an Rpi3 laptop with a battery and display and all that. So I need a way to battery power my Pi. Could I power my Pi3 (5v@2.5a) a usb power bank (one that could provide 5v@2-2.5amps obviously) with perhaps a step down/set up regulator? But I still would need a way to power the screen. Most driver boards want 11-12v and I don't know how to provide that. Maybe wiring batteries in series or parallel? I'm not exactly sure on how that works but I'm new to LiPo's so I'd like some help please. Thanks!

Question by gupperino   |  last reply


Battery Powered LED Strip

Hi, I have one 6V Alkaline Battery (or two 3V Coin cell battery) that i am using to light a fairy LED strip (see here). I'd like to know for how long the battery will last me for. Can you please direct me what parameters I need to collect for the battery (or the LEDs) and what equations i will be using to determine the operating time of the battery. Thank you for your support in advance, Regards,

Topic by Greensal   |  last reply


battery isolation for portable power. Answered

Iv been trying to wrap my head around what im trying to do and cant quite figure it out. Pretty much i have salvaged 8 18650 size cells that i would like to run in parallel to make a portable battery. In order to boost capacity, i would like to buy new cells and make another pack that is parallel also. I want them parallel so its a nominal 3.7v system that i can boost to 5v for USB devices I know its bad to run old and new batteries in parallel do to various reasons such as self discharge. My idea is have 2 usb ports for one pack and 2 ports for the other pack and have an input/output protection PCB per pack. Now to keep this more portable i only want to use 1 charger and this is what confuses me. I can charge each pack separately, but that would require me to swap packs on the charger, and i would rather not have to worry about doing that. Long story short, how can i charge 2 battery packs at the same time but keep them isolated from each other? Diodes maybe? Also with how the protection circuits work having the charge leads connected to the output leads and the batteries on there own leads, when the charger is outputting over one amps, will it hurt any device plugged into it or will it regulate the current down to one amp with no harm done? Link to usb charger and protection circuit. http://www.ebay.com/itm/221424010115?_trksid=p2060353.m1438.l2649&ssPageName;=STRK%3AMEBIDX%3AIT http://www.ebay.com/itm/400679842464?_trksid=p2060353.m1438.l2649&ssPageName;=STRK%3AMEBIDX%3AIT

Question by Ksp3cialK   |  last reply


Flash Power Supplies

I don't have a lot of money to spend on stuff at the moment. What I do have is flash guns. Four of them in fact, three of which can be fired with triggers. Now I could invest in 16 rechargeable batteries. Or should that be 32 in case I run out? And a crap load of chargers.  And extensions cos we have no spare sockets in our house. But that just doesn't seem right to me.   Heres what I propose : 1) make some dummy batteries from wood with wire running through the middle.   Three of these go in each flash to carry the connections  2) a fourth dummy battery carries wires out of a small notch in the battery flap door 3) said wires are connected in parallel to a large rechargeable battery - I reckon a 6v from an old British motorcycle (fast draining) or from a granny wagon (deep cycle) should do the trick.  4) when I'm done shooting I charge this single battery from the mains charger I have (does 6/12v) I figure 4xAA batteries at 1.5v = a 6v battery, bu extra size should last longer, be more convenient than carrying around dozens of AAs and changing them and if I want to use AAs when our and about I still can   Any reasons tho wouldn't work or I shouldn't do it?

Topic by ohowson   |  last reply


Led powered by 9v

Hi all. I am new to this forum and need some help. I want to mount an led strip to the bottom of a roller skate. Everything I find already made up requires 12v. I need to keep the setup as small as possible for mounting reasons. How could I go about making a 12vdc led circuit work off a 9v battery or how could I wire up some led's on a flexible strip powered by a battery. I am thinking 9v because I can purchase a rechargeable set without draining the bank account each time. Any suggestions are welcomed. I have about 6" in length to mount the strip to. I would like multi color led but one solid color would also be fine. Thanks again for any suggestions.

Topic by rsfaze   |  last reply


Power an Alienware Alpha with a battery? Answered

Hello. I was looking at building my own "gaming laptop" by putting an Alienware Alpha (i3 edition http://www.amazon.com/dp/B00MA7AF74/ref=twister_B00PW1Z7TQ?_encoding=UTF8&psc=1) in a briefcase with a screen. Is there any way I can power these two items with a battery? Any help would be appreciated. Thank you.

Question by NobleN   |  last reply


Powering an Arduino with 9V batteries? Answered

I'm looking at powering my Arduino with 2 9V batteries wired in parallel (2 is optional, but if you think a single 9V battery can power an arduino + 16 LEDs simultaneously for >3 hours, let me know). I have a few different options for linear regulators. LM350 (3A), C33275 (300mA), LM7805 (1A, 5V) - I'm guessing I should use the LM7805 because it's fixed at 5 but I'm not sure. I'm not too electronics-savvy so as much help as you're patient enough to give would really be appreciated!

Question by jonrb   |  last reply


Help - Battery Powered 64

I have an extra adapter for my N64 (image of adapter above) I want to run it on a 12v 600mAh battery can I do it safely by soldering the connections inside this adapter. (image shown of adapter, it has wire setup on it) I dont want to kill the thing its our only one.

Topic by acer5050   |  last reply


Battery Power Capability (C)

I'm trying to understand a little bit more about batteries. I've learnt so far: "Volts,  amps, and  watts measure electricity. Volts measure the “pressure” under which electricity flows. Amps measure the amount of electric current. Watts measure the amount of work done by a certain amount of current at a certain pressure or voltage." Now I'm interested in knowing the maximum amount of energy you can draw from a battery at any one time. I presume you can't instantly drain a batteries full energy capacity at any one time. I have read that: "The way the power capability is measured is in C's. A C is the Amp-hour capacity divided by 1 hour. So the C of a 2Ah battery is 2A. The amount of current a battery 'likes' to have drawn from it is measured in C. The higher the C the more current you can draw from the battery without exhausting it prematurely. Lead acid batteries can have very high C values (10C or higher) , and lithium coin cells have very low ones (0.01C)" Am I write in saying a 1.2V 1200mAh has a power capability of 1.2C? In which case I should only ever draw 1.2C or less to preserve the battery? How do I increase this amount when using 2 batteries, if I wire two batteries together does the power capability increase to 2.4C for the above example batteries? If so do I have to wire them in parallel or series for this to work? Thank you.

Topic by jakespikey   |  last reply


AC Power from a Battery

I've got a Garmin Forerunner 201 that is recharged by plugging a cord into the wall socket. It has a cradle type device that serves to connect the device to the cord. It does not have a USB connector.The battery life is 12 hours, but I'm going on a four-day bike ride (camping overnight), so I need a way to charge it since I won't have access to AC power.I've searched projects and gotten lots of hits on creating a USB charger from batteries, but I can't find anything on creating a power pack (with outlet) for charging my device.Does anyone have any suggestions on what I could do/use? I'd hate to not be able to track my route after I'm done.

Topic by samfelis   |  last reply


Battery powered arduino + high power leds?

I'm desperately trying to design an arduino circuit that can power each color of a high power cree MC-E color RGB led. What is the smallest dimension rechargeable battery I can use to accomplish this and have it run for a few hours? I'm desperate!

Question by SpiffyChee   |  last reply


Battery conversion? Answered

I have a rc helicopter and the controler uses 6X aa batterys. I thought that it would be cheaper to use a 9 volt battery instead. Would it damage my remote? Also Would this affect battery life and if so by how much?

Question by David97   |  last reply


Batteries in a series?

So if you were building an electric car and needed to up your voltage by wiring multiple Pb batteries in a series would you only get the watt-hours of one battery like you do with capacitor capacitance, or would you get all of them combined, or at least a little power capacity boost.  Also, would using lithium-ion batteries like these in a series be ok. lithium

Question by jj.inc   |  last reply


power supply for LED's? Answered

I have a strip of LED's that have a warning that's says use only with a 12v class 2 power supply. Is this referring to an AC/DC transformer? Should I be able to run them straight from a 12v battery? If I am using a 12v battery is the class 2 circuitry still needed?

Question by MDheliMech   |  last reply


Small power source

I was planning to make LED jewelery, but would need a very small power source. In the best case it could be powered by the body's movement. Is there anything small enough to bit on a wrist, yet can power about 10 LEDs?

Topic by DemonDomen   |  last reply


Trying to construct a battery powered usb hub. Will this work??

Let me start of by saying that I suck at electronics and to tell me to build something from scratch would completely miss the point of why I am asking this :P What I want to do is use readymade components to combine into a portable usb hub. I want it to be highly customizable and powerful enough to power several usb devices at once. Such as powering several usb speakers, recharging a phone and so on for extended periods of time. And it has to be as energy efficient as possible without costing a gazillion bucks. If I was not at all worried about wasting power I would have solved it already :P Here are the parts I have picked out. 1. 12V Rechargeable Li-on Battery 9800mAH http://cgi.ebay.co.uk/12V-Rechargeable-Li-on-Battery-9800mAH-Portable-4-CCTV-/280640849302?pt=US_Batteries&hash;=item41577f8596#ht_4008wt_804 2. Hobbywing UBEC-8A  http://cgi.ebay.co.uk/Hobbywing-UBEC-8A-8A-UBEC-RC-model-/250806232080?pt=Radio_Control_Parts_Accessories&hash;=item3a65376410#ht_2324wt_785  3. Powered 7-Port Usb hub http://cgi.ebay.co.uk/USB-7-Port-HUB-Powered-AC-Adapter-Cable-High-Speed-/280620339173?pt=LH_DefaultDomain_3&hash;=item4156468fe5#ht_4224wt_804 I hope someone can help me out with confirming that my setup would work. Or tell my exactly why it would not. I would greatly appreciate it :) /Nicklas

Question by AlmostNormal   |  last reply


Battery stumper?

Somebody wanna tell me why when I got my brand new quad syma copter and I put 4 brand new rayovac rechargable batteries that measured 1.24 volts the hand controller would not turn on, and when I put in 4 old duracells that measured 1.14 that were just laying around and weren't brand new like the rayo's were and they worked, I'm stumped. Too much power?

Question by angpal59   |  last reply


Help with powering 5.5 feet of 12V 3528 LED strip

Hi! I need help with powering 5.5 feet (~1.67 meters) of 12V DC, 60 LED/meter, 4.8W/meter, 0.4A/meter LED strip. It also comes with a DC connector. Link to product: http://www.amazon.com/OPOWAY-Flexible-Strip-Light-Ribbon/dp/B007SE2MM0/ref=sr_1_103?ie=UTF8&qid;=1372054019&sr;=8-103&keywords;=led+strip+lighting+warm I would like to run the strip for at least 4 hours before replacing the batteries.   How can I power this? (preferably using battery packs with NiMH batteries or cheap lithium batteries) I'm also open to using my laptop battery for the day if it is a good alternative. 

Topic by squkyshoes   |  last reply


i want a solar powered battery which can store the energy for a long time- 1 day and it shud b fitted into an garment.?

Actually...i want one solar powered battery that can store the sun energy for a longer time.and can b later used.example:- like in the hillly regions..u dnt get power supply , so u can charge while downhill and use it when we can to hilly regions...ie it wnt b able to give sufficient solar energy...in that case i need one...and it shud b fitted into the garment.

Question by jijicurie   |  last reply


Laptop Power

Hi all. I have a really old dell laptop(given to me) that is missing a power supply. It requires 20v and 3.5 amps to run. I want to make a digital picture frame out of it. I wont be using the battery or cd player and maybe not even the hard drive(not yet decided). Any idea's on what to use as a power source? I don't need to charge a battery just need power. Could I use an old pcu? I know that I could combine the two 12v lines to get 24 ish volts but won't that fry the old thing? I don't want to buy a replacement power adapter cause it is so old and may not work anyway(plus I wont lie I'm cheap lol). Any suggestions?

Topic by jmiller634   |  last reply


Can a power adapter be built with batteries and a 110 power converter to power a battery powered flash or camcorder?

The idea is to take 4 AA 1.5 volt batteries that power the flash and wire them together. Then wire the 4 AA's to a 6 volt power adapter so I can plug it in to 110 volt out let. Thus making my flash hard wired.

Question by dgimeson   |  last reply


Battery Powered Vinyl Turntable Help

I recently purchased a Bush MTT1 vinyl turntable which I am trying to make portable so I can play records through a set of I-pod speakers on the move. I thought this was a good one to ‘mod’ as it has a built in preamp (one less thing to carry!). First of all I have swapped/removed the red/white output sockets and replaced them with a 3.5mm headphone jack so the speakers can easily be attached – this works great! The part I am stuck with is the turntable needs to be plugged in to the wall…and I want it to be battery powered. I have opened up the turntable and inside the wire from the wall goes straight into a transformer, then the transformer is wired to the turntable circuit with two blue wires. The transformer reads – 05/45 on the side, if that’s any use. All I need to know is what voltage is being supplied to the turntable by the transformer so I can remove it and put batteries in its place, how can I do this?, can it be done? Also wear the transformer connects to the circuit it says 'AC IN'. Can i just connect batteries? Please see attached photos for anymore information, thanks!  

Topic by superrob   |  last reply


What resistor (or do I need one)?

I'm designing a simple prop that requires 2 LEDs. I figure a 2AA batteries connected to a switch that splits into 2 resistors and then into 2 LEDs then back to the batteries. See diagram below. The LEDs should take 20mA at 1.9-2.0V. So what resistor should I put in between the switch and LEDs.

Question by lucek   |  last reply


battery life

Any one know about how long 4 double a's wired in series will last with a 200 milliamp load, here is what the online LED calculator said, I'm working on putting this in a small flashlight:Solution 0: 1 x 2 array uses 2 LEDs exactly +----|>|---/\/\/----+ R = 27 ohms +----|>|---/\/\/----+ R = 27 ohmsThe wizard says: In solution 0: each 27 ohm resistor dissipates 270 mW the wizard says the color code for 27 is red violet black the wizard thinks ½W resistors are needed for your application together, all resistors dissipate 540 mW together, the diodes dissipate 700 mW total power dissipated by the array is 1240 mW the array draws current of 200 mA from the source.-thanks

Topic by firemanfu   |  last reply


Power for 2 motors

Hello everyone, my question is regarding power supply for an Arduino UNO with an Adafruit Motor Shield. I want to use 2 motors that are 12V(link below). I know that the power supply needed should be about 1v more than that of the motor, bu if I want to use 2 motors, do I need to double the voltage of the battery? motor: http://www.abra-electronics.com/products/29DM12V-Single-Shaft-6V%252d12V-DC-Motor.html

Topic by vek11   |  last reply


Switch to battery power when mains power is lost ?

Hey Guys & Girls I need a circuit, if anyone can help me please..... I have a 5.5v wall charger connected to a battery that charges the battery. This battery is used to power led's that i use when we have power outages. I would like to have a circuit where the battery is constantly plugged into the charger with something to divert the power or switch it off when the battery is fully charged, the other part of the circuit needs to "sense" when the mains power goes out and then automatically switch the led's on to run off of the battery. anyone have a circuit for this lying around? thanks in advance for any help :)

Question by GhengisKhan1981   |  last reply


Circuit for power bank? Answered

Hello, Need a circuit design for the following requirement. Checked online available circuit designs but not sure if they meet all needs.  Looking for circuit design as per following details. 1. It will have one or two, 3.7 volts 2600 mah 18650 lithium batteries 2. Batteries will be charged using smart phone mobile charger or solar panel 10 to 20 volts and around 500 mah to 1 ah input 3. Will have mini usb connection for the same on pcb 4. Circuit should have battery level indication. While being charged, when they are fully charged LED should turn on indicating battery full. Also there should be one LED to show that the charging is in progress. When the battery charge drops below specific level another LED should turn on. 5. If we use 2 batteries then they will be connected parallel 6. Output voltage of the batteries should be 5 volts (so step up is required) and current should be appropriate for mobile charging 7. There should be provision for 2 USB connections. Load can be mobile charging / USB mini fan / USB mini keyboard LED (could be 2 at a time) 8. Circuit should be safe enough so no damage is caused to batteries / load etc.

Question by rahuldj   |  last reply