I am trying to run a single LED off of a car battery, but I keep on destroying the LEDs any suggestions?
2007-05-14 14:50:49 · 10 answers · asked by beefire9 2 in Science & Mathematics ➔ Engineering
The other answers, truthfully, are pretty wasteful. You need a simple regulator based on the LM 317. It is a variable 3 lead regulator. The device package usually has a schematic for a simple regulator on it. Radio Shack does carry this device. It will regulate from about 32 volts down to about 1.2 volts. While your application probably won't need it, I always put a small heat sink on mine, just in case.
One thing to remember with a voltage regulator, the input voltage needs to be 3 volts higher than the voltage output that you want. In your case, with a 12 volt input, this will not be a problem.
2007-05-14 16:42:10 · answer #1 · answered by Anonymous · 2⤊ 2⤋
If you put a resistor in series with the LED you should be ok. An LED is a diode. Not sure what type LED you are using but some LEDs draw about 20 milliamps (ma). The voltage drop across it is about 0.5 volts. So you need to add a resistor that limits the current to 20 ma. R=E/I = 11.5/.020 = 575 ohms.
2007-05-14 15:14:46 · answer #2 · answered by nevertheless 3 · 2⤊ 0⤋
The basic answer is to put in a voltage regulator circuit. You can this yourself with just a little knowledge (check out the links below). The most basic voltage regulator is a single "reverse-biased" Zener diode in parallel to your load (the LED). A Zener diode with a Zener Voltage of 1.5 V is what you're looking for, as the voltage across it will stay at 1.5V when operating in the reverse-bias mode. Adding a transistor (again, see the links below) will allow you to regulate the current to the LED, which I think should be less than 25 milliamps. This way, your output voltage will stay at 1.5 V and you won't kill the LED with too much current.
btw, if you aren't inclined to build this circuit, you can go to a place like Advance Auto Parts or Radio Shack and they should be able to hook you up with a little pre-made voltage regulator since your application is not uncommon.
2007-05-14 15:26:40 · answer #3 · answered by Paul N 2 · 0⤊ 1⤋
Several people have suggested a voltage regulator. That is one way to do it, but for your application - turning on an LED - it is way too complex.
Simply put a resistor in series. For most LED's, anything in the range 500-1000 Ohms should do it.
2007-05-14 18:20:44 · answer #4 · answered by knowmeansknow 4 · 2⤊ 0⤋
You can use some sort of voltage dropping network to get it down to the 1.5 volts the LED needs, but why not just use a 12 volt LED? Seems like a lot easier way to do it.
2007-05-14 14:56:01 · answer #5 · answered by skwonripken 6 · 0⤊ 2⤋
You could get a 12 volt LED, or get a resistor of some sort of you're absolutely SET on getting a 1.5 volt LED.
2007-05-14 14:58:31 · answer #6 · answered by Brett S 3 · 0⤊ 1⤋
The LED needs to be in series with a current limiting resistor. Try 1K ohm.
2007-05-14 16:15:57 · answer #7 · answered by Jim M 2 · 2⤊ 0⤋
thats ''normal'' because the power supply you are using is no regulated. if you want to regulate the output to get exactly 12Volts out of the PS use a 7812 integrated circuit, if you don't know how, a simple search in google will get you a lot website where you can find information, try typing ''12v 7812 power supply'' good luck
2016-03-18 23:52:44 · answer #8 · answered by Anonymous · 0⤊ 0⤋
1.5v Regulator
2016-12-18 07:31:04 · answer #9 · answered by ? 4 · 0⤊ 0⤋
How about a new Type...L I D
2007-05-14 15:21:39 · answer #10 · answered by Anonymous · 0⤊ 1⤋