Guest bang847 Posted March 17, 2002 Share Posted March 17, 2002 Anyone a good with electrical stuff here? I want to hook up multiple LEDs for use in my car.. but the LED are rated for 2.5v any ideas? Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 17, 2002 Share Posted March 17, 2002 buy some 12 volt rated ones sorry couldn't help myself. actually it sounds like you have to do a combination parrallel/series hookup. off the top of my head i would set it up in groups of five (12 devided by 2.5 comes out to 4.8 so just make it an even five LEDS) that are hooked in series to each other, this insures that each are getting the prescribed 2.5 volts (actually 2.4 volts but it shouldn't make a noticable differance in brightness). then just keep hooking those groups of five with each other in parrallel, that insures that each group of five will be supplied with the needed 12VDC. if that sounds confusing just let me know and i'll try to explain it better. but from the looks of it it will take some wiring but shouildn't be too difficult. just how comfartable are you with electronics? do you know the differance in mathmatic properties between a series circuit versus a parrallel circuit? what about pythageroums theroum? none of this is too hard but if you plan on doing your own tail lights you might want to find a good bok to read up on just so you don't end putting a lot of time in to the project and then fry it the first time you flip the switch, know what i mean vern hope i helped out. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 17, 2002 Share Posted March 17, 2002 oh sorry i just re read your post and noticed you didn't actually state you were doing tail lights. that can kinda change the situation a little bit. if you are uing them as dummy lights or some such just put a resistor in line with the LED that will drop 9.5VDC across it so that the LED only "sees" the left over 2.5VDC coming through after the resistor. Quote Link to comment Share on other sites More sharing options...
Guest bang847 Posted March 17, 2002 Share Posted March 17, 2002 I'm ok with electronics...I was thinking of buying LEDs bulk and making tailights.. but what do you mean a dummy lights? are you reffering to the running lights vs actual brake lights? The first post made sense to me but I didnt quite get your second post... I was actually thinking of running 2 different series for it.. one more thing is does each diode drop the voltage by 2.5? I thought that was with resistors and ohm's law? It's been a few years since high school physics... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted March 17, 2002 Share Posted March 17, 2002 dummy lights are those nice little LEDS in your dash that will light up if a certain condition is met like say, you lose oil pressure. that way you get a big red warning light telling you something is wrong. lets see here... how would be the best way to explain. okay here goes, in a series circuit your I(current), E(voltage), R(resistance), are going to be additive properties to one another. so for example say you have a simpl circuit that consists of a 12V DC battery in line with two 1000 ohm resistors. well because voltage is additive and your votlage "drop" can't be higher than your voltage "rise" (voltage supplied to circuit) you know that each resistor will drop 6V DC across them. then you can even take that V and determine the I drop across each resistor. so 6/1000= 0.006 or 6 milliamps. now say i take one resistor out and leave the other. that would mean i am now dropping all 12 across that one resistor since there is nobody else there to share the V with. when you do the sam math as before you should now get 12/1000= 0.012 or 12 milliamps. parallel circuits work differently, when you figure the valus for them you have to use the recipricle method. which is a pain in the ass. say that i take that same circuit from above but instead of series i hook the resistors in parallel,whach what happens. i hope i can explain this whitout being confusing but i'll try my best. since you are know looking at two resistors hooked in parallel to each other you can figure your total resistance frm those two resistors. "it should be 2000" is what probably pops in to your head right away but it isn't that simple. instead you have to use the formula 1/R1(resistor 1) + 1/R2(resistor 2)= 1/answer= answer. when we feed the resistor's values through this it should look like this 1/1000 + 1/1000= 1/0.002 = 500 ohms. this value is your total circuit resistance. so now you can take that 500 ohms and use it to find your circuit amperage. 12/500=0.024 and when you split it across your two resistors you will find that now each of them is dropping 12 milliamps instead of just 6. does that make sense? i know i'm not the best teacher im still in my college elctronics class and whats kinda funny is that we've gotten so far past this its kinda hard to remeber the "simple" stuff LOL. as to your last question on the diodes. diodes don't drop a set amount. the rating is just what voltage they operate at it is up to you to give them that "enviroment" if you run them outside their range they will usually burn up. if you look at my first post hopefully you should understand better why i said groups of five in line (additive properties) and then hook each group up in parrallel (so each group can see 12V DC to share) just remeber to hok them up with the LED's anode side on the negative side of the circuit. you can tell the anode by the fact that the LEAD on that side should be lnger than the other one. Quote Link to comment Share on other sites More sharing options...
jimzdat Posted March 17, 2002 Share Posted March 17, 2002 Hella Click on the product listing, then on "LED" at the top of the screen--they have a bunch of LED configurations--maybe it can be adapted to what you want? Quote Link to comment Share on other sites More sharing options...
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