I want to power a 60 mA LED using a stand 12 V DC car battery. Is this going to work or will it blow the LED?
399258
just put a limiting resistor. 60mA and 12V. Limiting resistor =R=(V-Vled)/I. assuming the extreme, 0V for Vled. R=12/6e-2=200ohm. that way the current will never exceed 60mA.
13921
If you mean a 12 volt mobile radio like a ham rig, you should need a 12 volt DC power supply.  The antenna will need a ground plane.
197325
it depends on the voltage the battery is prescribed to run at...which is gen 230v/220v and so u cant power the light bulb with the battery which is almost of 3v. or else its fine use a bulb holder along with its wires and place them one to the -ve terminal and the other to the positve terminal
883686
A long time ago I found a voltage regulator for an automotive alternator that would allow output at "line" voltage (for an application similar to yours), but unfortunately I lost the information on the source.  Check at an RV (Recreational Vehicle) dealer in your area for something like this - those folks have information on stuff like that..\n\nA standard automotive alternator isn't built for the sustained high power output you're describing.  You might be able to get a higher capacity unit better suited for your project from a heavy duty truck (or an RV) out of a junkyard and get it rebuilt (complete with the new voltage regulator) for a fraction of the price of a new one.\n\nWarning:  alternators typically output full capacity at frequencies far above 50 or 60 Hertz.  Your power diodes may not work well at higher line frequencies.\n\nAlso, have you checked into getting a gasoline engine powered 120 volt power supply, like what are typically sold for emergencies power outages and campers?  You can find them for a low few hundred dollars for 1000 watts, and would a lot cheaper in the long run than risking trashing car alternators....
1185964
Have you the original lead?...if so you'll be able to get the power rating etc and see if your local electrical retailer can help.
1116545
See sources for making a "lemon battery" or a "potato battery".  You'll probably need to hook several of these batteries together in parallel in order to get enough current to power an LCD, but it should be possible.  Alternatively, you can use pieces of copper and zinc sheet metal to increase the surface areas of the electrodes in each battery, which will increase the current produced by each battery.
1179766
You could solder onto the positive and negative parts of the battery case 2 wires with a female AC adaptor plug.  Problem is that i have no idea what mA, voltage, wattage, ohms, etc to use there.  Check the battery and look for the electrical information, or check the manufacturer's page for some schematics.  About 3 years ago i ran an old computer that way after the battery died since i didnt feel like roaming the globe for a battery that fit.\n\nYour safest bet is the battery and if it died, replacements are EASY to find on the internet nowadays.
877037
easy,you got to let the charge leak out.when your a car you can take your shoes off and stuff like that but there really is nothing to worry about just because the voltage can range from 10 000 to 20 000 volts it does not necessarily mean its going to harm you, it has a very low current(which does harm in high doses.
362726
my dear, hope u r big enough to under stand my answer.\nok i appreciate ur idea to conserve all the mechanical energy produced in a car, but the problem is c if the battery can run a car which requires 100w power that means the power delivered by the battery is 100w now that power is exactly sufficient to run the car but if u want to recharge the battery again u need 100w of more power which will increase the load on the same battery which is to be recharged. which is absurd. so my dear it is practically IMPOSSIBLE to manufacture a car of ur kind. hope u got my answer if u dint understand u go through it once again then also if u face problems do not hesitate to write to me ok bye.
325093
your question is not clear enough to answer. do you need to plug them in now? in which case you need any power converter that fits them. if you want to make them portable, that's a different problem.
81594
Use ohm's law (I=E/R); 2 AAs are 2.4 to ~3 volts depending on battery type, so 0.4 to 0.5 A.\nHOWEVER, if you measured the bulb's resistance cold, it will be higher when hot, so it will draw less current.
98948
All you really need is a source of high current. A car battery would work fine. The real question is what are you going to use as a "rod" and "flux"  Those are the critical issues.
700354
Since you have no contact info, I have no other choice...\n\nIn reference to http://answers.yahoo.com/question/index?qid=20061115060801AAEHWQA&r=w&pa=FZptHWf.BGRX3OFMhzdTUCYEW59bygAIQoCa4DY8zIlrypTkPQ--&paid=answered#NbUvWju8VzmdRHfXRHQU\n\nYou suggested to the asker to wire his sub to 1 ohm when it clearly states in his question "500 watts X 1 @ 4 ohms". You do realize you told him to blow his amp up by wiring it that way.
883981
If you really want to be technical about this then here you go:\n\nHere are the three main consideration you have to follow when making a flashlight:\n\n1.) Amount of current the bulb will draw:\nI standby this clearly to show that current draw will affect the size of the wire that you will use to power up the bulb.  If your bulb draws lots of current from the source, then you will want to use a bigger wire.\n\n2.) Safe wire colors\nSecondly you have to consider safety standards as well.  You can't simply start to wire up the flash light and put the red wire on the negative end of the battery / power source.   You can possibly confuse someone, if they intend to repair it. \nThus in DC CIRCUITS ONLY\nRed = Positive Voltage w/ respect to GND\nBlack = Ground
5115
If the laptop or the battery are powering up when the adapter is plugged in then, the LED may be faulty.  If the laptop does not power up or the battery doesnot charge then the adapter is definitely faulty.  Also try plugging the adapter into different wall socket.  If your adapter has a detachable "kettle lead" with plug, then try chaning this lead.\n\nBattery Wizard\nhttp://www.ComputerBatteries.co.uk
700902
Ok, at the risk of being blunt, if you need to ask this, you might be better of leaving things well alone - or doing as the other person suggested and using a transormer to lower the voltage to begin with.\n\nHowever.........\n\nFirst of all, you need to plonk a diode in line really, LED's do not like AC so the diode will make things into "raggy DC", using a bridge rectifier would be better and would reduce the flickering, as would plonking a capacitor over the DC output - typically with AT LEAST a 380V rating if using a bridge and a 200V rating if using a single diode.\n\nStill with me?\n\nYou now need to work out the voltage drop over the LED's - this varies according to type - and mainly colour. About 1.8V for a typical RED LED and around 4v for a white one.\n\nYou then need to look at how many volts you have "left" after you have taken into account all of the LED's in series.\n\nEG:  You take 220V, use a single diode (110 v) and then pop a cap over to stop the flicker (around 160V)\n\nYou now have 30 red, 20 green and 10 blue LED's in series. Assume 1.8V drop on Red, 2.2V on Green and 4.1V on blue.\n54v  + 44v + 22v = 120v\nThis gives us 40v to "burn off" with a resistor.\n\nLet us assume you want to drive the LED's at 20mA\n\nR = V/I   therefore  R = 40/.02 = 2000 Ohms\n\nPower = I x I x R  (current sqaured 8 resistance) so the resistor will be dissipating 800mW - Allowing for plenty of play and wanting a warm rather than hot resistor, then 2w ideally.\n\n\nSo a 2K2 resistor - or 1K8 for a bit brighter would be your answer here (for the number of LEDS and type), rated at 2W or better.\n\nAs I said at the beginning, if ONE step of this doesn't make GOOD sense to you, PLEASE leave WELL alone.\n\n\n\nPLEASE DO NOT use this as a way to hook up the leds exactly as shown WITHOUT first checking their "forward voltage losses", I have used typical examples, different models can vary considerably.
143229
odds are, that you would be beter off buying a manufactued device, dc to ac inverters are very complicated and have many different circuits. not only that, but for you to make something that can invert that much power would need an extreme amount of skill to to get the proper components. I would recomend geting a manufactured model from marine purposes perhaps. Some companies should offer custom built electronics.