LED Help
08-12-2005, 07:40 PM
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LED Help
Hello I have orderd some LED's and would like to know what resistors I should run. I bought the LED's from here... http://www.allelectronics.com/cgi-b...od el&start=16 I got the 2 ultrabright white and 2 ultrabright red ones. I want to put them on my Amphibious craft that runs off of a 6.0 volt battery. Anyone have any ideas on what resistor I should get? any help would be great! thanks a lot
08-12-2005, 10:13 PM
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RE: LED Help
Well on a 6V battery you're not going to get the brightness you are most likely looking for. These superbright LEDs work best on 3 - 3.5v EACH so you are going to be just shy of the voltage you need. Don't forget there will be a volt drop on each resistor as well. I'd highly recommend a 9V battery. It'll make things WAY easier.
The simplest way to figure out what rating you need for your resistors is to remember voltage divided by current = resistance. So, if you are runinng the LEDs on a 9V battery they'll each take around 3.5V so that's 7V for 2 LEDs which leaves 2V. That's the volt drop of the resistor. So if you want to run 30ma through the LEDs (that'll make them nice and bright and still get plenty of life out of them) you'd be looking for resistors in the 150 ohms range. That's assuming that you are running on a 9V battery with 1 resistor for each LED. I typically drive mine at a higher current for more brightness but they do die sooner. I'll go as far as a 90 ohm resistor for each LED.
How many LEDs are you planning to run here? Give me some time and I can see the last circuit I made for one of my cars. I'm at work right now so I can't check till tomorrow. I have headlights, driving lights and tail\brake lights on it. I'll see what size resistors I used on that one. It's INSANELY bright but the LEDS are lasting a long time. I didn't over drive them on this one.
Hope this helps.
Enjoymentboy
The simplest way to figure out what rating you need for your resistors is to remember voltage divided by current = resistance. So, if you are runinng the LEDs on a 9V battery they'll each take around 3.5V so that's 7V for 2 LEDs which leaves 2V. That's the volt drop of the resistor. So if you want to run 30ma through the LEDs (that'll make them nice and bright and still get plenty of life out of them) you'd be looking for resistors in the 150 ohms range. That's assuming that you are running on a 9V battery with 1 resistor for each LED. I typically drive mine at a higher current for more brightness but they do die sooner. I'll go as far as a 90 ohm resistor for each LED.
How many LEDs are you planning to run here? Give me some time and I can see the last circuit I made for one of my cars. I'm at work right now so I can't check till tomorrow. I have headlights, driving lights and tail\brake lights on it. I'll see what size resistors I used on that one. It's INSANELY bright but the LEDS are lasting a long time. I didn't over drive them on this one.
Hope this helps.
Enjoymentboy
08-13-2005, 12:27 PM
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RE: LED Help
well I am running 2 Ultrabright whites and 2 ultra bright reds (tail and headlights). I have orderd a ram lighting kit before and desided for the price I would rather just make my own kit for way cheaper! I know there was just one resistor for all the lights on the ram kit. wouldn't I just want something like that? if so what would that be?
08-16-2005, 01:16 PM
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RE: LED Help
If you went with a 9v battery and 4 LEDs they would not be at their brightest since they would be getting less than the typical 3-3.5V they need. That's assuming that they are all on at the same time. The ones I make have a separate resistor for each bank of lights (ie 1 for both headlights, another for the driving lights etc) but I use 2 for the tailights since I also have it setup for brake lights as well.
I've done a major cleanup in my garage and for the life of me I can't find the last one I made. I didn't forget about helping you but I have been swamped at work and I just haven't had time to dig through the boxes.
Give me a few days and I'll see what I can find.
Enjoymentboy
I've done a major cleanup in my garage and for the life of me I can't find the last one I made. I didn't forget about helping you but I have been swamped at work and I just haven't had time to dig through the boxes.
Give me a few days and I'll see what I can find.
Enjoymentboy
08-16-2005, 11:46 PM
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RE: LED Help
Alright thanks a lot for helping out! I will tell you now though that I don't know anything about resistors and stuff but I can learn. So if you know part numbers or what to call it so I could go to say, radioshack and ask for it, it would be great thanks!! woody.
08-21-2005, 10:02 AM
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RE: LED Help
Hi,
Sorry for taking so long to get you this info...it's been insane at work the past few weeks and I'm only really getting any time to myself now.
I have the last harness I built right beside me now so I can give you whatever info you need.
I have 6 leds on this in 3 separate circuits and all are fed from a common 9v battery source. Each circuit is 2 leds and one resistor with the exception of the taillight\brakelight where I have 2 resistors and a microswitch.
The headlights and driving lights are done the same but I use different leds in each one. Headlights are 5mm 10000mcd white and the driving lights are 3mm 8000mcd blue leds. The leds are in series with a 100 ohm 1 watt resistor in series as well.
The brake\taillights are a slightly differnt story. If you only want full time taillights then you can do it up the same as the headlights and it will work great. I like to have brake lights go on when I use the brakes so I have it setup like this: 2 12000mcd red leds in series with a 56 ohm resistor just like with the headlights. I then added a 470 ohm resistor in parrellel with the 56 ohm and a micro switch.
When the switch is off the taillights are driven accross both the 56 and 470 resistors which makes it a llittle dim. When you press the switch the 470 is shorted out and the brakelights are going over only the 56 ohm making them VERY bright.
You may want to play witht he resistors that you use if you go this way. I worked for a while with different ones to come up with a setup that I liked best. When I apply the brakes the current to the brakelights is a little too high so they do not last as long as they should but they are incredibly bright. You can't look right at them. I have a HUGE amount of these leds so I really don't care if I burn them out.
You could use a 100 ohm for the brakes and add a 600-800 ohm in parrallel for the taillights if you want them to last longer but I wasn't happy with how it looked.
Even on a high load these 9v batteries are only pushing in the area of 150mah anyway so I am not worried. I've gone through 2 batteries so far and I haven't had to replace any leds yet.
Take a look at these pics. I posted them on another forum a while back. They should help you out. One is a basic schematic for the circuit. The red blocks are the resistors. It's crude but it works quite well. The other is a pic of the lights lit up. The room was kind of bright and the battery was getting low so the leds don't look as bright as they really are but you'll get a good idea of what I'm talking about.
Enjoymentboy
Sorry for taking so long to get you this info...it's been insane at work the past few weeks and I'm only really getting any time to myself now.
I have the last harness I built right beside me now so I can give you whatever info you need.
I have 6 leds on this in 3 separate circuits and all are fed from a common 9v battery source. Each circuit is 2 leds and one resistor with the exception of the taillight\brakelight where I have 2 resistors and a microswitch.
The headlights and driving lights are done the same but I use different leds in each one. Headlights are 5mm 10000mcd white and the driving lights are 3mm 8000mcd blue leds. The leds are in series with a 100 ohm 1 watt resistor in series as well.
The brake\taillights are a slightly differnt story. If you only want full time taillights then you can do it up the same as the headlights and it will work great. I like to have brake lights go on when I use the brakes so I have it setup like this: 2 12000mcd red leds in series with a 56 ohm resistor just like with the headlights. I then added a 470 ohm resistor in parrellel with the 56 ohm and a micro switch.
When the switch is off the taillights are driven accross both the 56 and 470 resistors which makes it a llittle dim. When you press the switch the 470 is shorted out and the brakelights are going over only the 56 ohm making them VERY bright.
You may want to play witht he resistors that you use if you go this way. I worked for a while with different ones to come up with a setup that I liked best. When I apply the brakes the current to the brakelights is a little too high so they do not last as long as they should but they are incredibly bright. You can't look right at them. I have a HUGE amount of these leds so I really don't care if I burn them out.
You could use a 100 ohm for the brakes and add a 600-800 ohm in parrallel for the taillights if you want them to last longer but I wasn't happy with how it looked.
Even on a high load these 9v batteries are only pushing in the area of 150mah anyway so I am not worried. I've gone through 2 batteries so far and I haven't had to replace any leds yet.
Take a look at these pics. I posted them on another forum a while back. They should help you out. One is a basic schematic for the circuit. The red blocks are the resistors. It's crude but it works quite well. The other is a pic of the lights lit up. The room was kind of bright and the battery was getting low so the leds don't look as bright as they really are but you'll get a good idea of what I'm talking about.
Enjoymentboy
09-26-2005, 03:50 PM
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RE: LED Help
alright cool. I want to know what the little black thing is in this picture?
http://www2.towerhobbies.com/cgi-bin...&I=LXTB97&P=ML right next to the quarter which is wired to the battery thing and the rest of the lights. This is what I thought was a resistor but I guess it isn't? anyways I have had a couple of ram light kits with this and now need to know what it is so I can get it and put some of my own kits together for way cheaper! thanks for the help woody
[8D]
http://www2.towerhobbies.com/cgi-bin...&I=LXTB97&P=ML right next to the quarter which is wired to the battery thing and the rest of the lights. This is what I thought was a resistor but I guess it isn't? anyways I have had a couple of ram light kits with this and now need to know what it is so I can get it and put some of my own kits together for way cheaper! thanks for the help woody
[8D]
09-26-2005, 06:27 PM
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RE: LED Help
The black thing in the picture is probably a resistor box. The idea with LEDs is to flow a constant amount of current through them (the mcd (millicandle) output rating on most LEDs assumes 20 mA (milliamps) of current through them to get the listed brightness). If you run a resistor in series with each LED you can still get full brightness at 6 volts. (Sorry if the explanation gets a little technical - I am an electronics tech for a living and I figure more information is a good thing.)
Ask for or order a '1/4 watt carbon composition thruhole resistor' (a metal film instead of carbon comp resistor will work just fine - they are just a little pricier) - you can either get them from a local electronics store or get them from All Electronics or whoever. I would suggest a local electronics store - most online places sell resistor in bags of 100 (for about $1 per bag of 100) and you probably really don't need 100 resistors. Your local store will probably hit you for more like 5 to 10 cents each but it's still cheaper in the long run (especially when you have to add in shipping and usually a minimum order value from most online places).
Hook one end of the resistor to plus and the other end to the positive leg of the LED (the longer leg). Hook the short leg of the LED to the minus of the battery and you should have light - if not try reversing the polarity of the LED. You can't hurt an LED by hooking it up backwards (unless you have a really high voltage and 6V or even 9V through a series resistor won't do it) - it just won't light up. (Without the series resistor you will toast them even if they are hooked up right!) (Now, shorting anything directly from the plus to the minus of the battery is another matter completely - I would suggest avoiding that at all costs ;-).
If you go to a local store maybe they will let you try the experiment above and just buy the ones you want (Radio Shack probably won't let you but a local shop might help you out). The lower the ohm value (number) the brighter the LEDs will be but they will drain more current from your battery (shortening your run time though probably not noticeably) and at some point they will blow up. Try the brightness check with a fully charged battery so there aren't any surprises (like they blow out when you hook up a fresh battery off of the charger). Equipment boy likes to push his LEDs harder than I would normally - I'm just conservative like that - but I would go for a starting point around 220 ohms.
Let us know how it turns out!
Ask for or order a '1/4 watt carbon composition thruhole resistor' (a metal film instead of carbon comp resistor will work just fine - they are just a little pricier) - you can either get them from a local electronics store or get them from All Electronics or whoever. I would suggest a local electronics store - most online places sell resistor in bags of 100 (for about $1 per bag of 100) and you probably really don't need 100 resistors. Your local store will probably hit you for more like 5 to 10 cents each but it's still cheaper in the long run (especially when you have to add in shipping and usually a minimum order value from most online places).
Hook one end of the resistor to plus and the other end to the positive leg of the LED (the longer leg). Hook the short leg of the LED to the minus of the battery and you should have light - if not try reversing the polarity of the LED. You can't hurt an LED by hooking it up backwards (unless you have a really high voltage and 6V or even 9V through a series resistor won't do it) - it just won't light up. (Without the series resistor you will toast them even if they are hooked up right!) (Now, shorting anything directly from the plus to the minus of the battery is another matter completely - I would suggest avoiding that at all costs ;-).
If you go to a local store maybe they will let you try the experiment above and just buy the ones you want (Radio Shack probably won't let you but a local shop might help you out). The lower the ohm value (number) the brighter the LEDs will be but they will drain more current from your battery (shortening your run time though probably not noticeably) and at some point they will blow up. Try the brightness check with a fully charged battery so there aren't any surprises (like they blow out when you hook up a fresh battery off of the charger). Equipment boy likes to push his LEDs harder than I would normally - I'm just conservative like that - but I would go for a starting point around 220 ohms.
Let us know how it turns out!
09-26-2005, 10:38 PM
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RE: LED Help
there is a formula that will solve for the resistor ( ohms law), but the easiest way is to invest in a good meterlike this and just keep adding the resistors until you get the proper voltage, which is prob 1.5 to 2 volts at the end.
good luck and happy stomping
good luck and happy stomping
09-27-2005, 01:22 PM
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RE: LED Help
Yes that little package is where the resistors are. That's the part that you would make yourself. Only real difference between that and the part I made is the size. Mass production gives them the egde. I haven't had any trouble with mounting or anything so I can't imagine the RAM lights really performing any better. Esspecially enough to justify the added cost.
I do like to drive my LEDs a little harder than most people but I have a HUGE amount (multiple 1000's) so I don't mind if they die a little sooner. As I mentioned I havend had one die yet and I've now gone through 3 9v batteries.
I got the LEDs from ebay. If you do a search for them you will be amazed at the deals you can get.
Enjoymentboy
I do like to drive my LEDs a little harder than most people but I have a HUGE amount (multiple 1000's) so I don't mind if they die a little sooner. As I mentioned I havend had one die yet and I've now gone through 3 9v batteries.
I got the LEDs from ebay. If you do a search for them you will be amazed at the deals you can get.
Enjoymentboy
09-29-2005, 04:46 PM
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RE: LED Help
i hooked mine up by using a 9V battery and 4 leds, 2 white 2 blue. i put a resitor on my battery connector, o nthe negative side i believe. works great really nice led work
10-01-2005, 08:20 PM
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RE: LED Help
Hey, I am also setting up a high powered LED system on my truck. I will have two sets (only one set used at a time)- one pair of 24000 mcd headlights, and then a set with 12000mcd headlights and 5000mcd brakelights (switch operated). I ordered my 6 led's, resistors, and wire from www.lsdiodies.com . The entire order cost me $11 shipped! Check em out.
10-02-2005, 08:43 AM
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RE: LED Help
Enjoyment Boy - it appears you are running your led's in series? Why not run them parallel, in which can you can run all of them off of with as little as a 3 volt battery? In my model trains I run parallel high intensity led's off of 3 v - so bright you hurt your eyes. That way if one burns out they don't all go out in the string as well.
10-02-2005, 06:46 PM
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RE: LED Help
I run the 3 banks of LEDs in parallel with 2 in series on each bank (6 in all) specifically because I have better control over which ones I want to run. It made it much easier to setup the brake\tail lights this way too.
I also drive them at a higher rate than is typical and I have found that they usually pull 3.5v instead of 3. I used a multimeter to tune the resistor values to get the current draw I was looking for instead of trusting the colour codes on them.
Also I can run of a $0.95 9v battery for a LONG time and not have to worry. I actually use the ones I take out of the smoke detectors when I replace them so I have 5 or 6 of them around all the time.
I have around 5k LEDs sitting in my eletronics bin so I have an excuse if I need to replace one every so often. The only ones I have replaced though are the tail lights from when I was doing the initial build. I was running them at 100mah (SILLY bright) so they didn't last too long, but I have so many I really didn't care. The red ones I have are actually made for street crossing signs (the walk\don't walk signs) so they are bright and VERY tough. They are made to run at 40mah at 3.7v.
I use 7.2v rx packs on my boats so I just adjust the resistor values a little and they run off the main pack.
Honestly...it's just a matter of preference. I don't do it your way only because I haven't. I say if it works, great. If it doesn't, find out why and do it again.
Enjoymentboy
I also drive them at a higher rate than is typical and I have found that they usually pull 3.5v instead of 3. I used a multimeter to tune the resistor values to get the current draw I was looking for instead of trusting the colour codes on them.
Also I can run of a $0.95 9v battery for a LONG time and not have to worry. I actually use the ones I take out of the smoke detectors when I replace them so I have 5 or 6 of them around all the time.
I have around 5k LEDs sitting in my eletronics bin so I have an excuse if I need to replace one every so often. The only ones I have replaced though are the tail lights from when I was doing the initial build. I was running them at 100mah (SILLY bright) so they didn't last too long, but I have so many I really didn't care. The red ones I have are actually made for street crossing signs (the walk\don't walk signs) so they are bright and VERY tough. They are made to run at 40mah at 3.7v.
I use 7.2v rx packs on my boats so I just adjust the resistor values a little and they run off the main pack.
Honestly...it's just a matter of preference. I don't do it your way only because I haven't. I say if it works, great. If it doesn't, find out why and do it again.
Enjoymentboy
10-03-2005, 06:17 PM
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RE: LED Help
So I really don't know what you guys are talking about I don't undertand all the electrsity talk. so is there anyway you could give me part numbers of the stuff I would need to make a light kit. I order stuff from all electronics or radio shack. if you could tell me what to get I would thing that would be great thanks alot
10-08-2005, 08:40 AM
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RE: LED Help
Woodymaxx
I'll do you one better. If you email me a mailing address I'll send you a bunch of parts and instructions so you can make a harness. I've got a bunch of stuff just sitting around and I'd like to see it get used. No charge.
Enjoymentboy
I'll do you one better. If you email me a mailing address I'll send you a bunch of parts and instructions so you can make a harness. I've got a bunch of stuff just sitting around and I'd like to see it get used. No charge.
Enjoymentboy
